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1. Scientific detector workshop 2022 on‐sky performance verification of near‐infrared <scp> e − APD </scp> technology for wavefront sensing and demonstration of <scp> e − APD </scp> pixel performance to improve the sensitivity of large science focal planes

Author: Gert Finger, Frank Eisenhauer, Rainer Genzel, Christopher Mandla, Ian Baker, Domingo Alvarez, Antonio Amorim, Wolfgang Brandner, Christophe Dupuy, Casey Deen, Derek Ives, Leander Mehrgan, Manfred Meyer, Karin Perraut, Guy Perrin, Jörg Stegmeier, Christian Straubmeier, Harald J. Weller, and Vincent Isgar
Subjects: Space and Planetary Science, Astronomy and Astrophysics
Published: 2023

2. Grism design for improving the spectral capabilities of GRAVITY+ at the VLTI

Author: Joel Sanchez-Bermudez, Rebeca García-López, Salvador Cuevas, Frank Eisenhauer, Christian Straubmeier, and Senol Yazici
Published: 2022

3. GRAVITY+ Wide: towards hundreds of z ~ 2 AGN

Author: Antonia Drescher, Maximilian Fabricius, Taro Shimizu, Julien Woillez, Pierre Bourget, Felix Widmann, Jinyi Shangguan, Christian Straubmeier, Matthew Horrobin, Nicolas Schuhler, Frank Eisenhauer, Frederic Gonté, Stefan Gillessen, Thomas Ott, Guy Perrin, Thibaut Paumard, Wolfgang Brandner, Laura Kreidberg, Karine Perraut, Jean-Baptiste Le Bouquin, Paulo J. V. Garcia, Sebastian Hoenig, Denis Defrère, Guillaume Bourdarot, Helmut Feuchtgruber, Reinhard Genzel, Michael Hartl, Frank Haussmann, Dieter Lutz, Nikhil More, Christian Rau, Jonas Sauter, Sinem Uysal, Patrick Wessely, Ekkehard Wieprecht, Lukas Wimmer, and Senol Yazici
Published: 2022

4. The GRAVITY+ adaptive optics testbench: a laboratory adaptive optics integration bench that reproduces an UT Coudé focus

Author: Florentin Millour, Philippe Bério, Stéphane Lagarde, Sylvie Robbe-Dubois, Carole Gouvret, Olivier Lai, Fatmé Allouche, Christophe Bailet, Olivier Boebion, Marcel Carbillet, Aurélie Marcotto, Alain Spang, Paul Girard, Nicolas Mauclert, Jean-Baptiste Lebouquin, Thibaut Paumard, Férréol Soulez, Julien Woillez, Nikhil More, Frank Eisenhauer, Christian Straubmeier, Laura Kreidberg, Paulo J. V. Garcia, and Sebastian Hoenig
Published: 2022

5. GRAVITY faint: reducing noise sources in GRAVITY$^+$ with a fast metrology attenuation system

Author: Felix Widmann, Stefan Gillessen, Thomas Ott, Taro Shimizu, Frank Eisenhauer, Maximilian Fabricius, Julien Woillez, Frédéric Gonté, Matthew Horrobin, Jingyi Shangguan, Senol Yazici, Guy Perrin, Thibaut Paumard, Wolfgang Brandner, Laura Kreidberg, Christian Straubmeier, Karin Perraut, Jean-Baptiste Le Bouquin, Paulo Garcia, Sebastian Hönig, Denis Defrère, Guillaume Bourdarot, Antonia Drescher, Helmut Feuchtgruber, Reinhard Genzel, Michael Hartl, Dieter Lutz, Nikhil More, Christian Rau, Sinem Uysal, Ekkehard Wieprecht, Merand, A, Sallum, S, and Sanchez-Bermudez, J
Subjects: Technology, Science & Technology, FOS: Physical sciences, Optics, Astronomy & Astrophysics, interferometry, near-infrared, VLTI, GRAVITY, noise-suppression, Physical Sciences, Astrophysics - Instrumentation and Methods for Astrophysics, Instruments & Instrumentation, Instrumentation and Methods for Astrophysics (astro-ph.IM)
Abstract: With the upgrade from GRAVITY to GRAVITY$^+$ the instrument will evolve into an all-sky interferometer that can observe faint targets, such as high redshift AGN. Observing the faintest targets requires reducing the noise sources in GRAVITY as much as possible. The dominant noise source, especially in the blue part of the spectrum, is the backscattering of the metrology laser light onto the detector. To reduce this noise we introduce two new metrology modes. With a combination of small hardware changes and software adaptations, we can dim the metrology laser during the observation without losing the phase referencing. For single beam targets, we can even turn off the metrology laser for the maximum SNR on the detector. These changes lead to an SNR improvement of over a factor of two averaged over the whole spectrum and up to a factor of eight in the part of the spectrum currently dominated by laser noise., Comment: Proceeding of SPIE Astronomical Telescopes + Instrumentation 2022
Published: 2022
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6. A geometric distance to the supermassive black Hole of NGC 3783

Author: N. M. Förster Schreiber, M. L. Bolzer, Pierre-Olivier Petrucci, E. Sturm, Jason Dexter, Thibaut Paumard, Florentin Millour, Christopher A. Onken, Christian Straubmeier, Sebastian F. Hönig, Daniel Rouan, Makoto Kishimoto, Reinhard Genzel, Yann Clénet, P. T. de Zeeuw, Julien Woillez, Ric Davies, D. Kaltenbrunner, António Amorim, A. Drescher, Jinyi Shangguan, S. von Fellenberg, D. Gratadour, Misty C. Bentz, Linda J. Tacconi, J. Stadler, Karine Perraut, Felix Widmann, P. Vermot, Amiel Sternberg, Thomas Ott, Paulo J. V. Garcia, Rachel Street, Wolfgang Brandner, Odele Straub, Dieter Lutz, Hagai Netzer, Mercedes Prieto, Taro Shimizu, Stefan Gillessen, Konrad R. W. Tristram, Oliver Pfuhl, M. Bauböck, Frank Eisenhauer, Andreas Eckart, Guy Perrin, Sylvestre Lacour, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and GRAVITY
Subjects: Length scale, Gravity (chemistry), Cosmology and Nongalactic Astrophysics (astro-ph.CO), Galaxies: Seyfert, Active galactic nucleus, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, symbols.namesake, Angular diameter, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Galaxies: nuclei, Physics, Supermassive black hole, Distance scale, Quasars: individual: NGC 3783, Astronomy and Astrophysics, Galaxies: active, Light curve, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), symbols, Reverberation mapping, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Hubble's law, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The angular size of the broad line region (BLR) of the nearby active galactic nucleus (AGN) NGC 3783 has been spatially resolved by recent observations with VLTI/GRAVITY. A reverberation mapping (RM) campaign has also recently obtained high quality light curves and measured the linear size of the BLR in a way that is complementary to the GRAVITY measurement. The size and kinematics of the BLR can be better constrained by a joint analysis that combines both GRAVITY and RM data. This, in turn, allows us to obtain the mass of the supermassive black hole in NGC3783 with an accuracy that is about a factor of two better than that inferred from GRAVITY data alone. We derive $M_\mathrm{BH}=2.54_{-0.72}^{+0.90}\times 10^7\,M_\odot$. Finally, and perhaps most notably, we are able to measure a geometric distance to NGC 3783 of $39.9^{+14.5}_{-11.9}$ Mpc. We are able to test the robustness of the BLR-based geometric distance with measurements based on the Tully-Fisher relation and other indirect methods. We find the geometric distance is consistent with other methods within their scatter. We explore the potential of BLR-based geometric distances to directly constrain the Hubble constant, $H_0$, and identify differential phase uncertainties as the current dominant limitation to the $H_0$ measurement precision for individual sources., 9 pages and 5 figures in main text, Accepted for publication in A&A
Published: 2021

7. Constraining particle acceleration in Sgr A⋆ with simultaneous GRAVITY, Spitzer, NuSTAR, and Chandra observations

Author: Wolfgang Brandner, A. Jiménez-Rosales, Mark Gurwell, Stefan Hippler, Christian Straubmeier, Th. Henning, Fiona A. Harrison, Jason Dexter, N. M. Förster Schreiber, F. Vincent, Pierre Kervella, Daryl Haggard, S. Yazici, Silvia Scheithauer, Oliver Pfuhl, Y. Dallilar, T. Taro Shimizu, Idel Waisberg, Odele Straub, K. Foster, Felix Widmann, Sera Markoff, Dieter Lutz, J.-B. Le Bouquin, M. Bauböck, Matthew Horrobin, Yann Clénet, P. T. de Zeeuw, Gabriele Ghisellini, Howard A. Smith, Frederick K. Baganoff, Daniel Stern, Thibaut Paumard, Eckhard Sturm, Ric Davies, M. Nowak, Andreas Eckart, Andreas Kaufer, Sebastian Rabien, Laurent Jocou, Paulo J. V. Garcia, Ekkehard Wieprecht, Reinhard Genzel, Jinyi Shangguan, G. Rodríguez-Coira, Patrick Lowrance, C. J. Hailey, Thomas Ott, S. Zhang, A. Drescher, G. Ponti, Giovanni G. Fazio, Steven P. Willner, S. D. von Fellenberg, Linda J. Tacconi, Maryam Habibi, H. Bonnet, Julien Woillez, V. Lapeyrère, Sylvestre Lacour, António Amorim, Erich Wiezorrek, Xavier Haubois, Guy Perrin, J. Neilsen, K. Mori, Eric Gendron, Frank Eisenhauer, G. Heißel, Pierre Léna, Joseph L. Hora, Karine Perraut, Charles F. Gammie, Feng Gao, G. Witzel, Gérard Zins, Mark Morris, André Young, Julia Stadler, Jean-Phillipe Berger, Hope Boyce, Stefan Gillessen, Lieselotte Jochum, Roberto Abuter, High Energy Astrophys. & Astropart. Phys (API, FNWI), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: Accretion, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, Electron, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Astrophysics - high energy astrophysical phenomena, law.invention, Luminosity, symbols.namesake, law, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Accretion (meteorology), Galaxy: center, 010308 nuclear & particles physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astronomy and Astrophysics, Black hole physics, Synchrotron, ddc, Particle acceleration, Lorentz factor, 13. Climate action, Space and Planetary Science, Accretion disks, symbols, Spectral energy distribution, Flare
Abstract: We report the time-resolved spectral analysis of a bright near-infrared and moderate X-ray flare of Sgr A*. We obtained light curves in the $M$-, $K$-, and $H$-bands in the mid- and near-infrared and in the $2-8~\mathrm{keV}$ and $2-70~\mathrm{keV}$ bands in the X-ray. The observed spectral slope in the near-infrared band is $\nu L_\nu\propto \nu^{0.5\pm0.2}$; the spectral slope observed in the X-ray band is $\nu L_\nu \propto \nu^{-0.7\pm0.5}$. We tested synchrotron and synchrotron self-Compton (SSC) scenarios. The observed near-infrared brightness and X-ray faintness, together with the observed spectral slopes, pose challenges for all models explored. We rule out a scenario in which the near-infrared emission is synchrotron emission and the X-ray emission is SSC. A one-zone model in which both the near-infrared and X-ray luminosity are produced by SSC and a model in which the luminosity stems from a cooled synchrotron spectrum can explain the flare. In order to describe the mean SED, both models require specific values of the maximum Lorentz factor $\gamma_{max}$, which however differ by roughly two orders of magnitude: the SSC model suggests that electrons are accelerated to $\gamma_{max}\sim 500$, while cooled synchrotron model requires acceleration up to $\gamma_{max}\sim5\times 10^{4}$. The SSC scenario requires electron densities of $10^{10}~\mathrm{cm^{-3}}$ much larger than typical ambient densities in the accretion flow, and thus require in an extraordinary accretion event. In contrast, assuming a source size of $1R_s$, the cooled synchrotron scenario can be realized with densities and magnetic fields comparable with the ambient accretion flow. For both models, the temporal evolution is regulated through the maximum acceleration factor $\gamma_{max}$, implying that sustained particle acceleration is required to explain at least a part of the temporal evolution of the flare., Comment: accepted for publication in Astronomy & Astrophysics; preview abstract shortened due to arXiv requirements
Published: 2021

8. Black Hole At The Center Of The Milky Way, The

Author: Andreas Eckart, Christian Straubmeier, Rainer Schodel
Published: 2005

9. The GRAVITY Young Stellar Object survey. VII. The inner dusty disks of T Tauri stars

Author: A. Drescher, S. von Fellenberg, R. Garcia-Lopez, E. F. van Dishoeck, Lucas Labadie, Gilles Duvert, Christian Straubmeier, Myriam Benisty, Th. Henning, Jerome Bouvier, Stefan Gillessen, Sylvestre Lacour, Julia Stadler, T. Taro Shimizu, Silvia Scheithauer, Felix Widmann, Eckhard Sturm, P. Garciaınst, R. Grellmann, Laurent Jocou, Paola Caselli, Evelyne Alecian, Jean-Phillipe Berger, T. Ott, Z. Hubert, V. Lapeyrère, Eric Gendron, Frank Eisenhauer, Frederic H. Vincent, J. Sanchez-Bermudez, Andreas Eckart, A. Caratti o Garatti, A. P. Sousa, Pierre Léna, António Amorim, Natascha M. Förster-Schreiber, Pierre Kervella, L. Klarmann, Odele Straub, Dieter Lutz, J.-B. Le Bouquin, Thibaut Paumard, R. Genzel, Catherine Dougados, Y.-I. Bouarour, Yann Clénet, P. T. de Zeeuw, Wolfgang Brandner, Ric Davies, Jinyi Shangguan, Matthew Horrobin, Francois Menard, G. Heissel, Karine Perraut, Linda J. Tacconi, Guy Perrin, Stefan Hippler, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)
Subjects: Gravity (chemistry), Techniques: Interferometric, Young stellar object, Continuum (design consultancy), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Techniques: High Angular Resolution, Infrared: ISM, Physics, Earth and Planetary Astrophysics (astro-ph.EP), [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 010308 nuclear & particles physics, Astronomy and Astrophysics, Radius, Astrophysics - Astrophysics of Galaxies, Accretion (astrophysics), Stars, T Tauri star, Instrumentation: High Angular Resolution, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Circumstellar Matter, Astrophysics::Earth and Planetary Astrophysics, Stars: Formation, Astrophysics - Earth and Planetary Astrophysics
Abstract: These protoplanetary disks in T Tauri stars play a central role in star and planet formation. We spatially resolve at sub-au scales the innermost regions of a sample of T Tauri's disks to better understand their morphology and composition. We extended our homogeneous data set of 27 Herbig stars and collected near-IR K-band observations of 17 T Tauri stars, spanning effective temperatures and luminosities in the ranges of ~4000-6000 K and ~0.4-10 Lsun. We focus on the continuum emission and develop semi-physical geometrical models to fit the interferometric data and search for trends between the properties of the disk and the central star. The best-fit models of the disk's inner rim correspond to wide rings. We extend the Radius-luminosity relation toward the smallest luminosities (0.4-10 Lsun) and find the R~L^(1/2) trend is no longer valid, since the K-band sizes measured with GRAVITY are larger than the predicted sizes from sublimation radius computation. No clear correlation between the K-band half-flux radius and the mass accretion rate is seen. Having magnetic truncation radii in agreement with the K-band GRAVITY sizes would require magnetic fields as strong as a few kG, which should have been detected, suggesting that accretion is not the main process governing the location of the half-flux radius of the inner dusty disk. Our measurements agree with models that take into account the scattered light. The N-to-K band size ratio may be a proxy for disentangling disks with silicate features in emission from disks with weak and/or in absorption silicate features. When comparing inclinations and PA of the inner disks to those of the outer disks (ALMA) in nine objects of our sample, we detect misalignments for four objects., Comment: Accepted for publication in A&A; 20 pages, 15 figures, 9 tables
Published: 2021
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10. Detection of faint stars near Sagittarius A* with GRAVITY

Author: Christian Straubmeier, Stefan Hippler, Th. Henning, Feng Gao, Gérard Zins, Maryam Habibi, Linda J. Tacconi, Oliver Pfuhl, V. Lapeyrère, Xavier Haubois, Guy Perrin, A. Jiménez-Rosales, Felix Widmann, G. Heißel, António Amorim, Stefan Gillessen, Yann Clénet, P. T. de Zeeuw, H. Bonnet, Jason Dexter, Paulo J. V. Garcia, Julien Woillez, Ric Davies, Lieselotte Jochum, Eric Gendron, G. Rodríguez-Coira, Eckhard Sturm, Laurent Jocou, Jinyi Shangguan, S. Yazici, T. Taro Shimizu, Thibaut Paumard, M. Nowak, M. Bauböck, Karine Perraut, Reinhard Genzel, N. M. Förster Schreiber, Wolfgang Brandner, Matthew Horrobin, Julia Stadler, Thomas Ott, Idel Waisberg, A. Drescher, S. von Fellenberg, Sebastian Rabien, Ekkehard Wieprecht, F. Vincent, Pierre Kervella, Jean-Philippe Berger, Odele Straub, Dieter Lutz, J.-B. Le Bouquin, Sylvestre Lacour, Silvia Scheithauer, Y. Dallilar, Andreas Kaufer, Frank Eisenhauer, Pierre Léna, Erich Wiezorrek, Roberto Abuter, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris - Site de Meudon (OBSPM), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), and GRAVITY
Subjects: Astrophysics - instrumentation and methods for astrophysics, Stars: imaging, Proper motion, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics - astrophysics of galaxies, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Supermassive black hole, Galaxy: center, 010308 nuclear & particles physics, Galactic Center, Astronomy and Astrophysics, Infrared: stars, Stars, Sagittarius A, 13. Climate action, Space and Planetary Science, Magnitude (astronomy), Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Radio astronomy, Gravitational redshift
Abstract: International audience; The spin of the supermassive black hole that resides at the Galactic Center can, in principle, be measured by accurate measurements of the orbits of stars that are much closer to Sgr A* than S2, the orbit of which recently provided the measurement of the gravitational redshift and the Schwarzschild precession. The GRAVITY near-infrared interferometric instrument combining the four 8m telescopes of the VLT provides a spatial resolution of 2–4 mas, breaking the confusion barrier for adaptive-optics-assisted imaging with a single 8–10m telescope. We used GRAVITY to observe Sgr A* over a period of six months in 2019 and employed interferometric reconstruction methods developed in radio astronomy to search for faint objects near Sgr A*. This revealed a slowly moving star of magnitude 18.9 in the K-band within 30 mas of Sgr A*. The position and proper motion of the star are consistent with the previously known star S62, which is at a substantially greater physical distance, but in projection passes close to Sgr A*. Observations in August and September 2019 detected S29 easily, with K-magnitude of 16.6, at approximately 130 mas from Sgr A*. The planned upgrades of GRAVITY, and further improvements in the calibration, offer greater chances of finding stars fainter than K-magnitude of 19.Key words: Galaxy: center / stars: imaging / infrared: stars⋆ GRAVITY was developed as part of a collaboration by the Max Planck Institute for extraterrestrial Physics, LESIA of the Observatoire de Paris/Université PSL/CNRS/Sorbonne Université/Université de Paris and IPAG of Université Grenoble Alpes/CNRS, the Max Planck Institute for Astronomy, the University of Cologne, the CENTRA – Centro de Astrofisica e Gravitação, and the European Southern Observatory.⋆⋆ Corresponding authors: F. Gao, e-mail: fgao@mpe.mpg.de; T. Paumard, e-mail: thibaut.paumard@obspm.fr
Published: 2021

11. The GRAVITY Young Stellar Object survey VIII. Gas and dust faint inner rings in the hybrid disk of HD141569

Author: R. Grellmann, O. Pfuhl, V. Ganci, Eric Gendron, Feng Gao, Stefan Hippler, V. Coudé du Foresto, Guy Perrin, Gérard Rousset, Thibaut Paumard, Frederic H. Vincent, Catherine Dougados, A. Wojtczak, R. Genzel, A. Drescher, A. de Valon, Lucas Labadie, Gilles Duvert, E. F. van Dishoeck, G. Heissel, S. D. von Fellenberg, V. Lapeyrère, Mercedes E. Filho, Christian Straubmeier, Karine Perraut, Julia Stadler, Th. Henning, Paola Caselli, Felix Widmann, Z. Hubert, Stefan Gillessen, Matthew Horrobin, António Amorim, Odele Straub, R. Garcia Lopez, J.-B. Le Bouquin, L. Klarmann, Paulo J. V. Garcia, Jean-Phillipe Berger, G. Heißel, J. Sanchez-Bermudez, Andreas Eckart, Pierre Kervella, Silvia Scheithauer, Sylvestre Lacour, T. Ott, Frank Eisenhauer, Pierre Léna, T. Taro Shimizu, M. Bauböck, A. Caratti o Garatti, A. Jiménez-Rosales, Myriam Benisty, F. Eupen, Julien Woillez, Eckhard Sturm, Laurent Jocou, Wolfgang Brandner, Yann Clénet, P. T. de Zeeuw, and Jinyi Shangguan
Subjects: Physics, Protoplanetary disks, Earth and Planetary Astrophysics (astro-ph.EP), Young stellar object, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Planetary system, Stars, Infrared: planetary systems, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Techniques: interferometric, Radiative transfer, Spectral energy distribution, Astrophysics::Solar and Stellar Astrophysics, Emission spectrum, Astrophysics::Earth and Planetary Astrophysics, Spectral resolution, Stars: individual: HD 141569, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Line (formation), Astrophysics - Earth and Planetary Astrophysics
Abstract: The formation and evolution of planetary systems impact the primordial accretion disk. HD141569 is the only known pre-main sequence star characterized by a hybrid disk. Observations probed the outer-disk structure showing a complex system of rings and interferometric observations attempted to characterize its inner 5 au region, but derived limited constraints. The goal of this work was to explore with new high-resolution interferometric observations the properties of the dust and gas in the internal regions of HD141569. We observed HD141569 on mas scales with GRAVITY/VLTI in the near-infrared at low and high spectral resolution. We interpreted the visibilities and spectral energy distribution with geometrical models and radiative transfer techniques to constrain the dust emission. We analyzed the high spectral resolution quantities to investigate the properties of the Br-Gamma line emitting region. Thanks to the combination of three different epochs, GRAVITY resolves the inner dusty disk in the K band. Data modeling shows that an IR excess of about 6% is spatially resolved and that the origin of this emission is confined in a ring of material located at a radius of 1 au from the star with a width smaller than 0.3 au. The MCMax modeling suggests that this emission could originate from a small amount of QHPs, while large silicate grain models cannot reproduce at the same time the observational constraints on the properties of near-IR and mid-IR fluxes. The differential phases in the Br-Gamma line clearly show an S-shape that can be best reproduced witha gas disk in Keplerian rotation, confined within 0.09 au. This is also hinted at by the double-peaked Br-Gamma emission line shape. The modeling of the continuum and gas emission shows that the inclination and position angle of these two components are consistent with a system showing relatively coplanar rings on all scales., Comment: Accepted for publication in A&A; 25 pages, 15 figures, 5 tables
Published: 2021
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12. MOLsphere and pulsations of the Galactic Center’s red supergiant GCIRS 7 from VLTI/GRAVITY

Author: Karine Perraut, Xavier Haubois, Jason Dexter, Christian Straubmeier, Th. Henning, F. H. Vincent, Linda J. Tacconi, Eckhard Sturm, Idel Waisberg, Stefan Hippler, Guy Perrin, Vincent Lapeyrere, J. Sanchez-Bermudez, Felix Widmann, Andreas Kaufer, Thomas Ott, A. Drescher, O. Pfuhl, Julien Woillez, G. Rodríguez-Coira, Laurent Jocou, Jean-Philippe Berger, Eric Gendron, Lieselotte Jochum, Gérard Zins, S. von Fellenberg, Paulo J. V. Garcia, Sylvestre Lacour, Stefan Gillessen, M. Nowak, N. M. Förster Schreiber, Julia Stadler, Matthew Horrobin, Feng Gao, António Amorim, Frank Eisenhauer, Pierre Léna, Odele Straub, J.-B. Le Bouquin, Erich Wiezorrek, M. Habibi, Reinhard Genzel, Silvia Scheithauer, H. Bonnet, Thibaut Paumard, Pierre Kervella, A. Jiménez-Rosales, Andreas Eckart, Ekkehard Wieprecht, S. Yazici, T. Taro Shimizu, M. Bauböck, Roberto Abuter, Jinyi Shangguan, Wolfgang Brandner, Yann Clénet, P. T. de Zeeuw, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Département de Chimie Moléculaire - Ingéniérie et Intéractions BioMoléculaires (DCM - I2BM), Département de Chimie Moléculaire (DCM), Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Extraterrestrische Physik (MPE), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Wageningen University and Research [Wageningen] (WUR), European Southern Observatory [Santiago] (ESO), European Southern Observatory (ESO), Poznan Technical University, Max Planck Institute for Astronomy (MPIA), GRAVITY Collaboration, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics [LESIA], Récepteurs nucléaires, maladies cardiovasculaires et diabète - U 1011 [RNMCD], Département de Chimie Moléculaire - Ingéniérie et Intéractions BioMoléculaires [DCM - I2BM], Max-Planck-Institut für Extraterrestrische Physik [MPE], Laboratoire d'études spatiales et d'instrumentation en astrophysique [LESIA], Wageningen University and Research [Wageningen] [WUR], European Southern Observatory [Santiago] [ESO], European Southern Observatory [ESO], Institut Européen des membranes [IEM], Institut de Planétologie et d'Astrophysique de Grenoble [IPAG], Max Planck Institute for Astronomy [MPIA], Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Universidade de Lisboa = University of Lisbon (ULISBOA), Centro de Astrofísica e Gravitação (CENTRA), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Leiden University, University of Colorado [Boulder], Universität zu Köln = University of Cologne, Max Planck Institute for Radio Astronomy, Universidade do Porto = University of Porto, University of California [Berkeley] (UC Berkeley), University of California (UC), Institute of Astronomy [Cambridge], University of Cambridge [UK] (CAM), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Weizmann Institute of Science [Rehovot, Israël], Sciences, EDP, Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut Européen des membranes (IEM), and Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Galaxy: nucleus, techniques: interferometric, stars: individual: GCIRS 7, stars: fundamental parameters, supergiants, Astrophysics - astrophysics of galaxies, Extinction (astronomy), Continuum (design consultancy), FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, Astrophysics - solar and stellar astrophysics, 0103 physical sciences, Red supergiant, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, Photosphere, 010308 nuclear & particles physics, Galactic Center, Astronomy and Astrophysics, Stars, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Supergiant, [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: GCIRS 7, the brightest star in the Galactic central parsec, formed $6\pm2$ Myr ago together with dozens of massive stars in a disk orbiting the central black-hole. It has been argued that GCIRS 7 is a pulsating body, on the basis of photometric variability. We present the first medium-resolution ($R=500$), K-band spectro-interferometric observations of GCIRS 7, using the GRAVITY instrument with the four auxiliary telescopes of the ESO VLTI. We looked for variations using two epochs, namely 2017 and 2019. We find GCIRS 7 to be moderately resolved with a uniform-disk photospheric diameter of $\theta^*_\text{UD}=1.55 \pm 0.03$ mas ($R^*_\text{UD}=1368 \pm 26$ $R_\odot$) in the K-band continuum. The narrow-band uniform-disk diameter increases above 2.3 $\mu$m, with a clear correlation with the CO band heads in the spectrum. This correlation is aptly modeled by a hot ($T_\text{L}=2368\pm37$ K), geometrically thin molecular shell with a diameter of $\theta_\text{L}=1.74\pm0.03$ mas, as measured in 2017. The shell diameter increased ($\theta_\text{L}=1.89\pm0.03$ mas), while its temperature decreased ($T_\text{L}=2140\pm42$ K) in 2019. In contrast, the photospheric diameter $\theta^*_\text{UD}$ and the extinction up to the photosphere of GCIRS 7 ($A_{\mathrm{K}_\mathrm{S}}=3.18 \pm 0.16$) have the same value within uncertainties at the two epochs. In the context of previous interferometric and photo-spectrometric measurements, the GRAVITY data allow for an interpretation in terms of photospheric pulsations. The photospheric diameter measured in 2017 and 2019 is significantly larger than previously reported using the PIONIER instrument ($\theta_*=1.076 \pm 0.093$ mas in 2013 in the H band). The parameters of the photosphere and molecular shell of GCIRS 7 are comparable to those of other red supergiants that have previously been studied using interferometry., Comment: 12 pages, 11 figures, 3 tables. Accepted for publication in Astronomy and Astrophysics (A&A)
Published: 2021

13. GRAVITY upgrade with high-performance grisms with factor >2 enhanced throughput

Author: Guy Perrin, Alejandra Rosales, Christian Straubmeier, Odele Straub, Eckhard Sturm, Laurent Jocou, Frank Eisenhauer, Ekkehard Wieprecht, Karine Perraut, M. Riquelme, O. Pfuhl, Andreas Eckart, Tim de Zeeuw, Jinyi Shangguan, Erich Wiezorrek, M. Bauböck, António Amorim, P. Guajardo, V. Lapeyrere, C. Rau, Martin G. F. Mayer, Kateryna Kravchenko, Takashi Sukegawa, Thomas Ott, Maryam Habibi, Felix Widmann, A. Buron, F. Haussmann, Julia Stadler, Sebastiano von Fellenberg, Sylvestre Lacour, Yukinobu Okura, Wolfgang Brandner, Reinhard Genzel, L. Barl, Senol Yazici, Stefan Gillessen, Feng Gao, Thibaut Paumard, David M. Huber, Paolo Garcia, Laurent Pallanca, Tuthill, P.G., Mérand, A., and Sallum, S.
Subjects: Grism, Physics, Interferometry, Gravity (chemistry), Optics, Upgrade, Spectrometer, business.industry, Instrumentation, Astrometry, business, Throughput (business)
Abstract: During the past years, the VLTI-instrument GRAVITY has made spectacular discoveries with phase-referenced interferometric imaging with milliarcsecond resolution and ten microarcsecond astrometry. Here, we report on the upgrade of the GRAVITY science spectrometer with two new grisms in October 2019, increasing the instrument throughput by a factor > 2. This improvement was made possible by using a high refractive index Germanium substrate, which reduces the grism and groove angles, and by successfully applying an anti-reflection coating to the ruled surface to overcome Fresnel losses. We present the design, manufacturing, and laboratory testing of the new grisms, as well as the results from the re-commissioning on sky.
Published: 2021

14. The mass of β Pictoris c from β Pictoris b orbital motion

Author: Matthias Samland, Anne-Lise Maire, David Mouillet, Andreas Eckart, Valentin Christiaens, Julien Woillez, Sarah Blunt, K. Perraut, T. Paumard, T. Ott, Myriam Benisty, E. Nasedkin, A. Mérand, Z. Hubert, Stefan Hippler, Frank Eisenhauer, Roderick Dembet, Gilles Otten, F. H. Vincent, Pierre Léna, Jinyi Shangguan, Miriam Keppler, Ekkehard Wieprecht, G. Bourdarot, M. Houllé, Odele Straub, Alexander J. Bohn, M. Nowak, Felix Widmann, K. Ward-Duong, P. T. de Zeeuw, J.-B. Le Bouquin, Julia Stadler, T. Taro Shimizu, A. Boccaletti, David K. Sing, Ji Wang, Linda J. Tacconi, Arthur Vigan, Elodie Choquet, Jens Kammerer, Claudia Paladini, J. Rameau, R. J. García López, Xavier Haubois, E. Rickman, Guy Perrin, J. P. Berger, Wolfgang Brandner, Eric Gendron, G. Heißel, H. Bonnet, Laurent Jocou, A. Cridland, S. D. von Fellenberg, Pierre Kervella, R. Asensio-Torres, G. Rousset, O. Pfuhl, Erich Wiezorrek, M. Bonnefoy, Y. Clénet, Senol Yazici, R. Abuter, John D. Monnier, Laura Kreidberg, Paulo J. V. Garcia, Zafar Rustamkulov, Tomas Stolker, Gilles Duvert, Paul Mollière, H. Beust, Eckhard Sturm, António Amorim, Anne-Marie Lagrange, Paola Caselli, Christian Straubmeier, Th. Henning, G. Chauvin, Benjamin Charnay, Sylvestre Lacour, E. F. van Dishoeck, Jason Dexter, Stefan Gillessen, André Young, D. Lutz, V. Coudé du Foresto, R. Genzel, Feng Gao, J. H. Girard, Faustine Cantalloube, L. Rodet, Sasha Hinkley, A. Drescher, Vincent Lapeyrere, Laurent Pueyo, Matthew Horrobin, M. L. Bolzer, Institut des Sciences Chimiques de Rennes (ISCR), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), MacoPharma, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Caltech Department of Astronomy [Pasadena], California Institute of Technology (CALTECH), Departamento de Astronomía, Universidad de Chile = University of Chile [Santiago] (UCHILE), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, European Southern Observatory (ESO), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Max-Planck-Institut für Astronomie (MPIA), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Observatoire Astronomique de l'Université de Genève (ObsGE), Université de Genève (UNIGE), Service de Pathologie respiratoire et allergologie [CHU Limoges], CHU Limoges, University of Auckland [Auckland], the GRAVITY Collaboration, Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Harvard University-Smithsonian Institution, and Université de Genève = University of Geneva (UNIGE)
Subjects: Astrophysics - instrumentation and methods for astrophysics, planets and satellites: detection, 010504 meteorology & atmospheric sciences, Astrophysics, Astrophysics - Earth and planetary astrophysics, 01 natural sciences, High angular resolution, Planet, instrumentation: high angular resolution, 0103 physical sciences, Beta Pictoris, 10. No inequality, instrumentation: interferometers, 010303 astronomy & astrophysics, Instrumentation, 0105 earth and related environmental sciences, Orbital elements, Physics, Interferometers, Astronomy and Astrophysics, Astrometry, Exoplanet, Radial velocity, Detection, Space and Planetary Science, Orbital motion, Planets and satellites, Eccentricity (mathematics), [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: Aims.We aim to demonstrate that the presence and mass of an exoplanet can now be effectively derived from the astrometry of another exoplanet.Methods.We combined previous astrometry ofβPictoris b with a new set of observations from the GRAVITY interferometer. The orbital motion ofβPictoris b is fit using Markov chain Monte Carlo simulations in Jacobi coordinates. The inner planet,βPictoris c, was also reobserved at a separation of 96 mas, confirming the previous orbital estimations.Results.From the astrometry of planet b only, we can (i) detect the presence ofβPictoris c and (ii) constrain its mass to 10.04−3.10+4.53MJup. If one adds the astrometry ofβPictoris c, the mass is narrowed down to 9.15−1.06+1.08MJup. The inclusion of radial velocity measurements does not affect the orbital parameters significantly, but it does slightly decrease the mass estimate to 8.89−0.75+0.75MJup. With a semimajor axis of 2.68 ± 0.02 au, a period of 1221 ± 15 days, and an eccentricity of 0.32 ± 0.02, the orbital parameters ofβPictoris c are now constrained as precisely as those ofβPictoris b. The orbital configuration is compatible with a high-order mean-motion resonance (7:1). The impact of the resonance on the planets’ dynamics would then be negligible with respect to the secular perturbations, which might have played an important role in the eccentricity excitation of the outer planet.
Published: 2021

15. Improved GRAVITY astrometric accuracy from modeling of optical aberrations

Author: Stefan Hippler, Maryam Habibi, S. Yazici, Paulo J. V. Garcia, T. Taro Shimizu, Roberto Abuter, F. Vincent, Linda J. Tacconi, M. Bauböck, Pierre Kervella, Guy Perrin, Idel Waisberg, G. Heißel, Karine Perraut, Eckhard Sturm, Laurent Jocou, Lieselotte Jochum, Sebastian Rabien, Julien Woillez, A. Jiménez-Rosales, Gérard Zins, M. Nowak, Odele Straub, Dieter Lutz, J.-B. Le Bouquin, Ekkehard Wieprecht, Julia Stadler, Reinhard Genzel, Wolfgang Brandner, Feng Gao, Thomas Ott, A. Drescher, N. M. Förster Schreiber, S. von Fellenberg, Christian Straubmeier, Silvia Scheithauer, Ric Davies, Y. Dallilar, Th. Henning, H. Bonnet, Jinyi Shangguan, Eric Gendron, Andreas Eckart, Yann Clénet, P. T. de Zeeuw, Thibaut Paumard, Jason Dexter, Andreas Kaufer, Felix Widmann, Frank Eisenhauer, Pierre Léna, V. Lapeyrère, Xavier Haubois, Erich Wiezorrek, Matthew Horrobin, Sylvestre Lacour, António Amorim, Jean-Philippe Berger, G. Rodríguez-Coira, Oliver Pfuhl, Stefan Gillessen, André Young, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: Astrophysics - instrumentation and methods for astrophysics, Field (physics), Astrophysics - astrophysics of galaxies, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, 010309 optics, Telescope, law, Methods: data analysis, 0103 physical sciences, Binary star, Calibration, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics, Physics, Galaxy: center, Galactic Center, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrometry, Galaxy: fundamental parameters, Interferometry, Space and Planetary Science, Instrumentation: interferometers, Astrophysics of Galaxies (astro-ph.GA), Instrumentation: high angular resolution, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA]
Abstract: The GRAVITY instrument on the ESO VLTI pioneers the field of high-precision near-infrared interferometry by providing astrometry at the 10−100 μas level. Measurements at this high precision crucially depend on the control of systematic effects. We investigate how aberrations introduced by small optical imperfections along the path from the telescope to the detector affect the astrometry. We develop an analytical model that describes the effect of these aberrations on the measurement of complex visibilities. Our formalism accounts for pupil-plane and focal-plane aberrations, as well as for the interplay between static and turbulent aberrations, and it successfully reproduces calibration measurements of a binary star. The Galactic Center observations with GRAVITY in 2017 and 2018, when both Sgr A* and the star S2 were targeted in a single fiber pointing, are affected by these aberrations at a level lower than 0.5 mas. Removal of these effects brings the measurement in harmony with the dual-beam observations of 2019 and 2020, which are not affected by these aberrations. This also resolves the small systematic discrepancies between the derived distance R0 to the Galactic Center that were reported previously.
Published: 2021
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16. Static phase aberrations in near-IR interferometry and GRAVITY's determination of the galactic center distanceStatic phase aberrations in near-IR interferometry and GRAVITY's determination of the galactic center distance

Author: M. Nowak, Reinhard Genzel, Wolfgang Brandner, K. Rousselet-Perraut, Julien Woillez, Christian Straubmeier, Eckhard Sturm, Sylvestre Lacour, Felix Widmann, Sebastiano von Fellenberg, M. Bauböck, Guy Perin, Jinyi Shangguan, Odele Straub, Frank Eisenhauer, A. Jiménez-Rosales, Paulo J. V. Garcia, António Amorim, Stefan Gillessen, Julia Stadler, Feng Gao, O. Pfuhl, and Thomas Ott
Subjects: Physics, Gravity (chemistry), business.industry, Zernike polynomials, Galactic Center, Phase (waves), Astrometry, Interferometry, symbols.namesake, Optics, Optical path, symbols, Calibration, business
Abstract: The GRAVITY instrument has revolutionized optical/IR interferometry: fringe-tracking and phase-referencing allow for 30 micro-arcsecond astrometry in a dual beam mode, and for spectro-differential astrometry better than 10 micro-arcseconds. The control of systematic effects is essential to fully exploit this technological advancement. Among those systematics are static phase aberrations, introduced along the instrument's optical path, which in particular affect the inferred separation of two unresolved objects within the same FOV. Here, we present how the aberrations can be measured, characterized by low-order Zernike polynomials and, most importantly, how their impact on the astrometry is corrected. The resulting astrometry corrections are verified with calibration observations of a binary before we discuss how they affect GRAVITY's measurement of the galactic center distance.
Published: 2020

17. First four telescopes large-separation off-axis fringe-tracking interferometry with GRAVITY at the VLTI

Author: Jinyi Shangguan, Feng Gao, Wolfgang Brandner, Frank Eisenhauer, F. Haussmann, Thomas Ott, Guy Perrin, Christian Straubmeier, Pierre Bourget, Frédéric Gonté, Eckhard Sturm, Michael Hartl, Roderick Dembet, Antonia Drescher, Sebastiano von Fellenberg, Nicolas Schuhler, Stefan Gillessen, Jürgen Ott, Gérard Zins, Julien Woillez, Paulo J. V. Garcia, O. Pfuhl, Thibaut Paumard, Karine Perraut, Michi Bauboeck, Odele Straub, Mari Lena Bolzer, Reinhard Genzel, Dieter Lutz, Felix Widmann, António Amorim, Julia Stadler, A. Jiménez-Rosales, Taro Shimizu, Bruno Chazelas, and Matthew Horrobin
Subjects: Physics, Very Large Telescope, Galactic Center, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Quasar, Astrophysics::Cosmology and Extragalactic Astrophysics, Tracking (particle physics), Redshift, Interferometry, Palomar Testbed Interferometer, Astronomical interferometer, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: We present the successful demonstration of world's first large-separation ~30" off-axis fringe tracking with four telescopes in October 2019. With this technique we increase the sky-coverage for optical interferometry by orders of magnitude compared to current technology. Following the early work at the Palomar Testbed Interferometer, the first demonstration of off-axis fringe tracking at the Keck Interferometer and with PRIMA at the ESO Very Large Telescope Interferometer, and the breakthrough with the GRAVITY Galactic Center observations, we enhanced the VLTI infrastructure for GRAVITY to take advantage of the PRIMA Star separators and Differential Delay Lines for off-axis fringe tracking. In our presentation we give an introduction to the subject, present the enhancements of the VLTI, and present our results from the first on-sky operation in October 2019, with observations of the Orion Trapezium Cluster, a field brown dwarf, and a high redshift quasar.
Published: 2020

18. The warm calibration unit of METIS: Laboratory tests and proof-of-concept

Author: Lucas Labadie, M. Wiest, Monika Rutowska, Christian Straubmeier, Steffen Rost, and Sabine Graf
Subjects: Integrating sphere, Computer science, Aperture, Proof of concept, Instrumentation, Calibration, Metis, Point (geometry), Spectrograph, Remote sensing
Abstract: METIS, the mid-infrared imager and spectrograph for the wavelength range 2.9-14 µm (astronomical L-, M- and N bands), will be equipped with a calibration unit, developed at the University of Cologne, which task is to deliver simulated sources for the test and calibration of the main imaging and spectral functionalities of METIS. Our subsystem, as the full METIS instrument, is currently in the Phase C of the project, which leads to the Final Design Review expected by the end of 2021. In this contribution, we first briefly introduce the general concepts chosen for the Warm Calibration Unit (WCU) and then detail the laboratory work that is undertaken in Cologne to validate most of the concepts presented at the Preliminary Design Review. A core unit of the WCU is the integrating sphere combined with the black body, which is the hub delivering the calibration functionalities. We first report the measured spatial uniformity of the output port of the integrating sphere when fed with the black body source radiation. The measurement made using our uncooled thermal camera, evidences a spatial uniformity below 1% RMS. Longer integration times will further improve the final accuracy on this important parameter. We also take a closer look at the black body source and report on its flux temporal stability, which is found to be better than 1% over a 2h duration. We characterize time windows for different settings of the main WCU light source, which is the black body and stability and repeatability of the detected signal. Through different experiments we investigated the best options to manufacture the aperture mask that will be used to generate artificial point sources.
Published: 2020

19. Polarization analysis of GRAVITY and the VLTI

Author: Feng Gao, Christian Straubmeier, Nicolas Schuhler, O. Pfuhl, António Amorim, Jinyi Shangguan, M. Bauböck, Paulo J. V. Garcia, Eckhard Sturm, Jason Dexter, Wolfgang Brandner, Sylvestre Lacour, K. Rousselet-Perraut, Stefan Gillessen, Guy Perrin, Sebastiano von Fellenberg, Thomas Ott, Felix Widmann, A. Jiménez-Rosales, Xavier Haubois, Frank Eisenhauer, Odele Straub, and Reinhard Genzel
Subjects: Physics, Brewster's angle, Astrophysics::High Energy Astrophysical Phenomena, Galactic Center, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics, Polarization (waves), law.invention, General Relativity and Quantum Cosmology, symbols.namesake, Interferometry, law, symbols, Astrophysics::Solar and Stellar Astrophysics, Flare
Abstract: Instrumental polarization can have large effects on measurements with the VLTI, as it can alter measured polarization and introduce uncertainties. To understand these effects we measured and simulated the instrumental polarization of the VLTI and of GRAVITY. We are able to provide a calibration model for GRAVITY observations and quantify systematic uncertainties due to instrumental polarization. This work has shown to be crucial to measure the polarization of the galactic center black hole Sgr A* where we detect a swing in the polarization angle during flare events. While the analysis was done for GRAVITY, it also gives an important basis for the design of future near-infrared instruments at the VLTI.
Published: 2020

20. Observations of the 86 GHz SiO maser sources in the Central Parsec of the Galactic Centre

Author: Christian Straubmeier, N. Sabha, A. Borkar, Andreas Eckart, Alina Donea, L. Moser, Vladimir Karas, Laurant O. Sjouwerman, Silke Britzen, D. Kunneriath, Monica Valencia-Schneider, and Anton Zensus
Subjects: Telescope, Physics, Stars, law, Long period, Millimeter, Astrophysics, Emission spectrum, Maser, Submillimeter Array, law.invention, Parsec
Abstract: We present results of 3 mm observations of SiO maser sources in the Galactic Centre (GC) from observations with the Australia Telescope Compact Array between $2010-2014$, along the transitions of the SiO molecule at $v = 1, J = 2-1$ at 86.243 GHz and $v = 2, J = 2-1$ at 85.640 GHz. We also present the results of the 3 mm observations with Atacama Large Millimeter/Submillimeter Array (ALMA). We detected 5 maser sources from the ATCA data, IRS 7, IRS 9, IRS 10EE, IRS 12N, and IRS 28; and 20 sources from the ALMA data including 4 new sources. These sources are predominantly late-type giants or emission line stars with strong circumstellar maser emission. We analyse these sources and calculate their proper motions. We also study the variability of the maser emission. IRS 7, IRS 12N and IRS 28 exhibit long period variability of the order of $1 - 2$ years, while other sources show steady increase or decrease in flux density and irregular variability over observation timescales. This behaviour is consistent with the previous observations.
Published: 2020

21. The GRAVITY young stellar object survey: III. The dusty disk of RY Lup

Author: Christian Straubmeier, V. Coudé du Foresto, T. Ott, Th. Henning, Guy Perrin, Z. Hubert, Frank Eisenhauer, E. F. van Dishoeck, Pierre Léna, Mercedes E. Filho, Stefan Hippler, Yann Clénet, P. T. de Zeeuw, O. Pfuhl, Odele Straub, J.-B. Le Bouquin, A. Caratti o Garatti, Karine Perraut, F. Vincent, Pierre Kervella, Eckhard Sturm, Julia Stadler, Feng Gao, Laurent Jocou, Catherine Dougados, Jinyi Shangguan, R. Genzel, R. Garcia-Lopez, M. Wiest, Thibaut Paumard, Gilles Duvert, Paola Caselli, Wing-Fai Thi, Wolfgang Brandner, Y.-I. Bouarour, Silvia Scheithauer, R. Grellmann, Francois Menard, S. D. von Fellenberg, Paulo J. V. Garcia, Stefan Gillessen, F. Eupen, Sylvestre Lacour, J. Sanchez-Bermudez, Andreas Eckart, Eric Gendron, A. Natta, Felix Widmann, Matthew Horrobin, Jean-Phillipe Berger, A. Jiménez-Rosales, L. Klarmann, Myriam Benisty, M. Bauböck, António Amorim, Lucas Labadie, Gérard Rousset, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire Franco-Chilien d'Astronomie (LFCA), Universidad de Concepción [Chile]-Pontificia Universidad Católica de Chile (UC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Universidad de Chile, Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Leiden Observatory [Leiden], Universiteit Leiden [Leiden], Physikalisches Institut [Köln], Universität zu Köln, Faculty of Agronomy, University of Parakou, European Southern Observatory (ESO), SIM/IDL Faculdade de Ciências da Universidade de Lisboa (FCUL), University of Lisboa, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Max-Planck-Institut für Radioastronomie (MPIFR), Max Planck Institute for Extraterrestrial Physics (MPE), University of Brasilia [Brazil] (UnB), Universitat Politècnica de València (UPV), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Transport et Environnement (INRETS/LTE), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Swedish Space Corporation (SSC), HELMHOLTZ CENTRE FOR ENVIRONMENTAL RESEARCH UFZ HALLE SUR SAALE DEU, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire Univers et Théories (LUTH (UMR_8102)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), GRAVITY Collaboration, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology [2007-2019] (Grenoble INP [2007-2019])-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre National de la Recherche Scientifique (CNRS)-Universidad de Concepción [Chile]-Pontificia Universidad Católica de Chile (UC)-Universidad de Chile-Institut national des sciences de l'Univers (INSU - CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble [2020-....] (OSUG [2020-....]), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes [2020-....] (UGA [2020-....])-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes [2020-....] (UGA [2020-....]), Environnement Ville Société (EVS), École normale supérieure - Lyon (ENS Lyon)-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Lumière - Lyon 2 (UL2)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Institut National des Sciences Appliquées (INSA)-Université de Lyon-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet [Saint-Étienne] (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS), Universitat Politecnica de Valencia (UPV), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Young stellar object, variables, Extinction (astronomy), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, stars: pre-main sequence, Herbig Ae/Be -stars, T Tauri, 01 natural sciences, circumstellar matter, Luminosity, stars: low-mass, stars: individual: RY Lup, protoplanetary disks -stars, 0103 physical sciences, low-mass, Astrophysics::Solar and Stellar Astrophysics, individual, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, stars: variables: T Tauri, Very Large Telescope, 010308 nuclear & particles physics, protoplanetary disks, Herbig Ae/Be, Astronomy and Astrophysics, Radius, Effective temperature, Astrophysics - Astrophysics of Galaxies, T Tauri star, Astrophysics - Solar and Stellar Astrophysics, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), pre-main sequencestars, Spectral energy distribution, Astrophysics::Earth and Planetary Astrophysics, RY Lup -circumstellar matter -stars, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: We use PIONIER data from the ESO archive and GRAVITY data that were obtained in June 2017 with the four 8m telescopes. We use a parametric disk model and the 3D radiative transfer code MCFOST to reproduce the Spectral Energy Distribution and match the interferometric observations. To match the SED , our model requires a stellar luminosity of 2.5 Lsun, higher than any previously determined values. Such a high value is needed to accommodate the circumstellar extinction caused by the highly inclined disk, which has been neglected in previous studies. While using an effective temperature of 4800 K determined through high-resolution spectroscopy, we derive a stellar radius of 2.29 Rsun. These revised fundamental parameters, when combined with the mass estimates available , lead to an age of 0.5-2.0 Ma for RY Lup, in better agreement with the age of the Lupus association than previous determinations. Our disk model nicely reproduces the interferometric GRAVITY data and is in good agreement with the PIONIER ones. We derive an inner rim location at 0.12~au from the central star. This model corresponds to an inclination of the inner disk of 50deg, which is in mild tension with previous determinations of a more inclined outer disk from SPHERE (70 deg in NIR) and ALMA(67 $\pm$5 deg) images, but consistent with the inclination determination from the ALMA CO spectra (55$\pm$5deg). Increasing the inclination of the inner disk to 70 deg leads to a higher line-of-sight extinction and therefore requires a higher stellar luminosity of 4.65 Lsun to match the observed flux levels. This luminosity would translate to a stellar radius of 3.13~Rsun, leading to an age of 2-3~Ma, and a stellar mass of about 2 Msun, in disagreement with the observed dynamical mass estimate of 1.3-1.5 Msun. Critically, this high-inclination inner disk model also fails to reproduce the visibilities observed with GRAVITY., Accepted for publication in A&A; 11 pages, 5 figures, 3 tables
Published: 2020

22. Direct confirmation of the radial-velocity planet β Pictoris c

Author: Benjamin Charnay, Feng Gao, Antoine Mérand, L. Rodet, H. Bonnet, Tyler Gardner, Jean-Phillipe Berger, E. F. van Dishoeck, Anthony Boccaletti, Stefan Gillessen, Felix Widmann, Eric Gendron, Hervé Beust, Karine Perraut, Wolfgang Brandner, A. Cridland, J. Rameau, Sasha Hinkley, R. Asensio-Torres, Stefan Hippler, Roderick Dembet, Thibaut Paumard, John D. Monnier, Claudia Paladini, Valentin Christiaens, Julien Woillez, Linda J. Tacconi, Gilles Otten, Z. Hubert, V. Lapeyrère, Xavier Haubois, António Amorim, Guy Perrin, Jinyi Shangguan, Jingxiu Wang, R. Garcia Lopez, David Mouillet, Erich Wiezorrek, M. Nowak, Reinhard Genzel, Sylvestre Lacour, P. Rubini, G. Heißel, Gilles Duvert, Odele Straub, J.-B. Le Bouquin, Thomas Ott, Jens Kammerer, Anne-Lise Maire, A. Drescher, Laura Kreidberg, G. Rodríguez-Coira, O. Pfuhl, Paulo J. V. Garcia, Laurent Pueyo, A. Grandjean, Frank Eisenhauer, Yann Clénet, P. T. de Zeeuw, Pierre Léna, Matthew Horrobin, V. Coudé du Foresto, Roberto Abuter, Anne-Marie Lagrange, S. D. von Fellenberg, Tomas Stolker, Gérard Rousset, F. Vincent, Pierre Kervella, Faustine Cantalloube, Julien Girard, Andreas Eckart, Arthur Vigan, Mickael Bonnefoy, Paul Mollière, Silvia Scheithauer, André Müller, Miriam Keppler, Ekkehard Wieprecht, E. Nasedkin, Christian Straubmeier, Th. Henning, Jason Dexter, Sarah Blunt, Myriam Benisty, M. Houllé, K. Ward-Duong, Julia Stadler, A. Jiménez-Rosales, Eckhard Sturm, Laurent Jocou, M. Kulikauskas, M. Bauböck, Elodie Choquet, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
Subjects: planets and satellites, Astrophysics, 01 natural sciences, Luminosity, formation -techniques, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, detection -planets and satellites, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Planetary core, Giant planet, Astronomy and Astrophysics, Orbital period, Exoplanet, Accretion (astrophysics), Radial velocity, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], interferometric, Astrophysics::Earth and Planetary Astrophysics
Abstract: Context.Methods used to detect giant exoplanets can be broadly divided into two categories: indirect and direct. Indirect methods are more sensitive to planets with a small orbital period, whereas direct detection is more sensitive to planets orbiting at a large distance from their host star. This dichotomy makes it difficult to combine the two techniques on a single target at once.Aims.Simultaneous measurements made by direct and indirect techniques offer the possibility of determining the mass and luminosity of planets and a method of testing formation models. Here, we aim to show how long-baseline interferometric observations guided by radial-velocity can be used in such a way.Methods.We observed the recently-discovered giant planetβPictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer.Results.This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature ofT = 1250 ± 50 K and a dynamical mass ofM = 8.2 ± 0.8 MJup. At 18.5 ± 2.5 Myr, this putsβPic c close to a ‘hot start’ track, which is usually associated with formation via disk instability. Conversely, the planet orbits at a distance of 2.7 au, which is too close for disk instability to occur. The low apparent magnitude (MK = 14.3 ± 0.1) favours a core accretion scenario.Conclusions.We suggest that this apparent contradiction is a sign of hot core accretion, for example, due to the mass of the planetary core or the existence of a high-temperature accretion shock during formation.
Published: 2020

23. Unveiling the β Pictoris system, coupling high contrast imaging, interferometric, and radial velocity data

Author: Christian Straubmeier, J. Hagelberg, Anne-Marie Lagrange, A. Grandjean, Frank Eisenhauer, Myriam Benisty, Silvano Desidera, R. Asensio-Torres, Anne-Lise Maire, M. Nowak, Thibaut Paumard, F. Cantalloube, Jens Kammerer, Yann Clénet, P. T. de Zeeuw, Matthew Horrobin, Karine Perraut, Eric Gendron, O. Pfuhl, L. Pueyo, Stefan Gillessen, Stefan Hippler, John Monnier, Raphael Galicher, P. Thebault, Gael Chauvin, C. Babusiaux, J. Wang, Wolfgang Brandner, L. Kreidberg, P. Léna, V. Lapeyrère, J. M. Girard, Sylvestre Lacour, G. Rodríguez-Coira, Guy Perrin, Matthew A. Kenworthy, H. Le Coroller, G. Heissel, F. Galland, V. Christiaens, P. Delorme, V. Coudé du Foresto, E. Choquet, Matthias Samland, Hervé Beust, Miriam Keppler, Odele Straub, Mickael Bonnefoy, Gilles Duvert, Andreas Eckart, Z. Wahhaj, T. Stolker, A. Zurlo, C. Paladini, F. Vincent, G. Otten, M. Janson, O. Flasseur, J.-B. Le Bouquin, A. Mérand, Felix Widmann, G. Rousset, Jinyi Shangguan, N. Meunier, Feng Gao, R. Gratton, A. Vigan, Paul Mollière, Jean-Phillipe Berger, P. Rubini, P. Kervella, T. Henning, António Amorim, T. Schmidt, Julien Woillez, Xavier Haubois, Anthony Boccaletti, Maud Langlois, Q. Kral, P. Garcia, Thomas Ott, L. Rodet, B. Charnay, R. Garcia Lopez, Reinhard Genzel, Sergio Messina, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Centre de Recherche Astrophysique de Lyon (CRAL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), European Southern Observatory [Santiago] (ESO), European Southern Observatory (ESO), CENTRA-SIM, IDL-Faculdade de Ciencias da Universidade de Lisboa, Departamento de Astronomía, Universidad de Chile = University of Chile [Santiago] (UCHILE), Max-Planck-Institut für Radioastronomie (MPIFR), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire des Combustibles Uranium (LCU), Service d'Analyses, d'Elaboration, d'Expérientations et d'Examens des combustibles (SA3E), Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Département d'Etudes des Combustibles (DEC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Physikalisches Institut [Köln], Universität zu Köln = University of Cologne, Max-Planck-Institut für Astronomie (MPIA), University of Freiburg [Freiburg], Space Telescope Science Institute (STSci), German Research Centre for Geosciences - Helmholtz-Centre Potsdam (GFZ), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), the GRAVITY Collaboration, Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Centre d'Immunologie de Marseille - Luminy (CIML), Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Observatoire de Paris - Site de Paris (OP), Universität zu Köln, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD), and Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: planets and satellites: detection, media_common.quotation_subject, Context (language use), Astrophysics, 01 natural sciences, Planet, radial velocities -planets and satellites, 0103 physical sciences, techniques: radial velocities, Astrophysics::Solar and Stellar Astrophysics, Eccentricity (behavior), 10. No inequality, planets and satellites: fundamental parameters, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common, Orbital elements, Physics, [PHYS]Physics [physics], detectionplanets and satellites, 010308 nuclear & particles physics, high angular resolution -techniques, Giant planet, techniques: high angular resolution, Astronomy and Astrophysics, Astrometry, Planetary system, Radial velocity, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], techniques, fundamental parameters
Abstract: Context. The nearby and young β Pictoris system hosts a well resolved disk, a directly imaged massive giant planet orbiting at ≃9 au, as well as an inner planet orbiting at ≃2.7 au, which was recently detected through radial velocity (RV). As such, it offers several unique opportunities for detailed studies of planetary system formation and early evolution. Aims. We aim to further constrain the orbital and physical properties of β Pictoris b and c using a combination of high contrast imaging, long base-line interferometry, and RV data. We also predict the closest approaches or the transit times of both planets, and we constrain the presence of additional planets in the system. Methods. We obtained six additional epochs of SPHERE data, six additional epochs of GRAVITY data, and five additional epochs of RV data. We combined these various types of data in a single Markov-chain Monte Carlo analysis to constrain the orbital parameters and masses of the two planets simultaneously. The analysis takes into account the gravitational influence of both planets on the star and hence their relative astrometry. Secondly, we used the RV and high contrast imaging data to derive the probabilities of presence of additional planets throughout the disk, and we tested the impact of absolute astrometry. Results. The orbital properties of both planets are constrained with a semi-major axis of 9.8 ± 0.4 au and 2.7 ± 0.02 au for b and c, respectively, and eccentricities of 0.09 ± 0.1 and 0.27 ± 0.07, assuming the HIPPARCOS distance. We note that despite these low fitting error bars, the eccentricity of β Pictoris c might still be over-estimated. If no prior is provided on the mass of β Pictoris b, we obtain a very low value that is inconsistent with what is derived from brightness-mass models. When we set an evolutionary model motivated prior to the mass of β Pictoris b, we find a solution in the 10–11 MJup range. Conversely, β Pictoris c’s mass is well constrained, at 7.8 ± 0.4 MJup, assuming both planets are on coplanar orbits. These values depend on the assumptions on the distance of the β Pictoris system. The absolute astrometry HIPPARCOS-Gaia data are consistent with the solutions presented here at the 2σ level, but these solutions are fully driven by the relative astrometry plus RV data. Finally, we derive unprecedented limits on the presence of additional planets in the disk. We can now exclude the presence of planets that are more massive than about 2.5 MJup closer than 3 au, and more massive than 3.5 MJup between 3 and 7.5 au. Beyond 7.5 au, we exclude the presence of planets that are more massive than 1–2 MJup. Conclusions. Combining relative astrometry and RVs allows one to precisely constrain the orbital parameters of both planets and to give lower limits to potential additional planets throughout the disk. The mass of β Pictoris c is also well constrained, while additional RV data with appropriate observing strategies are required to properly constrain the mass of β Pictoris b.
Published: 2020

24. A measure of the size of the magnetospheric accretion region in TW Hydrae

Author: Pierre Kervella, Y. Clénet, M. Filho, Stefan Hippler, Wolfgang Brandner, Tom Ray, Ekkehard Wieprecht, S. Yazici, S. von Fellenberg, O. Pfuhl, M. Bauboeck, J. Sanchez-Bermudez, Andreas Eckart, C. E. Garcia Dabo, A. Ramirez, R. Fedriani, Maryam Habibi, Paulo J. V. Garcia, F. H. Vincent, M. Koutoulaki, António Amorim, Julia Stadler, T. de Zeeuw, A. Jimenez Rosales, Feng Gao, Catherine Dougados, Felix Widmann, Karine Perraut, Lucas Labadie, Myriam Benisty, R. Garcia Lopez, Reinhard Genzel, H. Bonnet, A. Buron, E. F. van Dishoeck, Silvia Scheithauer, W. J. de Wit, Jinyi Shangguan, Stefan Gillessen, T. Ott, Frank Eisenhauer, T. Paumard, Sylvestre Lacour, Pierre Léna, V. Coudé du Foresto, Matthew Horrobin, Julien Woillez, Jean-Philippe Berger, F. Haussmann, A. Natta, L. Klarmann, Z. Hubert, Odele Straub, J.-B. Le Bouquin, Johann Kolb, Erich Wiezorrek, Eckhard Sturm, Laurent Jocou, Guy Perrin, A. Caratti o Garatti, R. Grellmann, Eric Gendron, Christian Straubmeier, Th. Henning, C. Rau, Xavier Haubois, M. Wiest, Roberto Abuter, Gilles Duvert, Paola Caselli, Gérard Zins, G. Rousset, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), School of Cosmic Physics [Dublin], and Dublin Institute for Advanced Studies (DIAS)
Subjects: Young stellar object, Astrophysics::High Energy Astrophysical Phenomena, Magnetosphere, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, 0103 physical sciences, TW Hydrae, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, Multidisciplinary, 010308 nuclear & particles physics, Stellar magnetic field, Radius, Accretion (astrophysics), Stars, T Tauri star, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, [SDU]Sciences of the Universe [physics], Astrophysics::Earth and Planetary Astrophysics
Abstract: Stars form by accreting material from their surrounding disks. There is a consensus that matter flowing through the disk is channelled onto the stellar surface by the stellar magnetic field. This is thought to be strong enough to truncate the disk close to the so-called corotation radius where the disk rotates at the same rate as the star. Spectro-interferometric studies in young stellar objects show that Hydrogen is mostly emitted in a region of a few milliarcseconds across, usually located within the dust sublimation radius. Its origin is still a matter of debate and it can be interpreted as coming from the stellar magnetosphere, a rotating wind or a disk. In the case of intermediate-mass Herbig AeBe stars, the fact that the Br gamma emission is spatially resolved rules out that most of the emission comes from the magnetosphere. This is due to the weak magnetic fields (some tenths of G) detected in these sources, resulting in very compact magnetospheres. In the case of T Tauri sources, their larger magnetospheres should make them easier to resolve. However, the small angular size of the magnetosphere (a few tenths of milliarcseconds), along with the presence of winds emitting in Hydrogen make the observations interpretation challenging. Here, we present direct evidence of magnetospheric accretion by spatially resolving the inner disk of the 60 pc T Tauri star TW Hydrae through optical long baseline interferometry. We find that the hydrogen near-infrared emission comes from a region approximately 3.5 stellar radii (R*) across. This region is within the continuum dusty disk emitting region (Rcont = 7 R*) and smaller than the corotation radius which is twice as big. This indicates that the hydrogen emission originates at the accretion columns, as expected in magnetospheric accretion models, rather than in a wind emitted at much larger distance (>1au)., Publish in Nature
Published: 2020

25. Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole

Author: Wolfgang Brandner, Thomas Ott, S. von Fellenberg, Thibaut Paumard, Jason Dexter, S. Yazici, V. Lapeyrère, Reinhard Genzel, Andreas Eckart, Xavier Haubois, Gérard Zins, Karine Perraut, Odele Straub, Stefan Hippler, Christian Straubmeier, Jean-Philippe Berger, António Amorim, M. Bauböck, J.-B. Le Bouquin, Th. Henning, Yann Clénet, P. T. de Zeeuw, Idel Waisberg, Eckhard Sturm, Sylvestre Lacour, Laurent Jocou, H. Bonnet, Jinyi Shangguan, Linda J. Tacconi, Silvia Scheithauer, Eric Gendron, Guy Perrin, M. Nowak, Maryam Habibi, Ekkehard Wieprecht, Felix Widmann, Andreas Kaufer, Julien Woillez, Matthew Horrobin, N. M. Förster Schreiber, Erich Wiezorrek, Frank Eisenhauer, Pierre Léna, Paulo J. V. Garcia, A. Jiménez-Rosales, G. Rodríguez-Coira, F. Vincent, Pierre Kervella, Oliver Pfuhl, Feng Gao, Vitor Cardoso, Lieselotte Jochum, Julia Stadler, Stefan Gillessen, Roberto Abuter, Observatoire de Paris, Université Paris sciences et lettres (PSL), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), GRAVITY, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Astrophysics and Astronomy, gr-qc, astro-ph.GA, black hole physics, Highly elliptical orbit, FOS: Physical sciences, Astrophysics, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, General Relativity and Quantum Cosmology, symbols.namesake, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, relativistic processes, Physics, Galaxy: nucleus, 010308 nuclear & particles physics, General Relativity and Cosmology, Astronomy and Astrophysics, Orbital period, Astrophysics - Astrophysics of Galaxies, Black hole, Radial velocity, Orbit, Space and Planetary Science, gravitation, [SDU]Sciences of the Universe [physics], Kepler orbit, Astrophysics of Galaxies (astro-ph.GA), [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Precession, symbols, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, Schwarzschild radius, astro-ph.IM
Abstract: The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black hole (candidate). Over the last 2.7 decades we have monitored the star's radial velocity and motion on the sky, mainly with the SINFONI and NACO adaptive optics (AO) instruments on the ESO VLT, and since 2017, with the four-telescope interferometric beam combiner instrument GRAVITY. In this paper we report the first detection of the General Relativity (GR) Schwarzschild Precession (SP) in S2's orbit. Owing to its highly elliptical orbit (e = 0.88), S2's SP is mainly a kink between the pre-and post-pericentre directions of motion ~ +- 1 year around pericentre passage, relative to the corresponding Kepler orbit. The superb 2017-2019 astrometry of GRAVITY defines the pericentre passage and outgoing direction. The incoming direction is anchored by 118 NACO-AO measurements of S2's position in the infrared reference frame, with an additional 75 direct measurements of the S2-Sgr A* separation during bright states ('flares') of Sgr A*. Our 14-parameter model fits for the distance, central mass, the position and motion of the reference frame of the AO astrometry relative to the mass, the six parameters of the orbit, as well as a dimensionless parameter f_SP for the SP (f_SP = 0 for Newton and 1 for GR). From data up to the end of 2019 we robustly detect the SP of S2, del phi = 12' per orbital period. From posterior fitting and MCMC Bayesian analysis with different weighting schemes and bootstrapping we find f_SP = 1.10 +- 0.19. The S2 data are fully consistent with GR. Any extended mass inside S2's orbit cannot exceed ~ 0.1% of the central mass. Any compact third mass inside the central arcsecond must be less than about 1000 M_sun., accepted to A&A
Published: 2020

26. The GRAVITY young stellar object survey. II. First spatially resolved observations of the CO bandhead emission in a high-mass YSO

Author: E. F. van Dishoeck, Feng Gao, Lucas Labadie, Wing-Fai Thi, Catherine Dougados, R. Fedriani, Paulo J. V. Garcia, Stefan Gillessen, Matthew Horrobin, Christian Straubmeier, J. Sanchez-Bermudez, Frederic H. Vincent, L. Klarmann, Th. Henning, Gérard Rousset, Eckhard Sturm, Laurent Jocou, Andreas Eckart, Thibaut Paumard, R. Grellmann, A. Caratti o Garatti, Arjan Bik, T. Ott, Odele Straub, Bernard Lazareff, V. Coudé du Foresto, Frank Eisenhauer, H. Linz, J.-B. Le Bouquin, Eric Gendron, António Amorim, Tom Ray, Jean-Phillipe Berger, Pierre Léna, Paola Caselli, Silvia Scheithauer, Sylvestre Lacour, Felix Widmann, Paulo Gordo, Gilles Duvert, R. Garcia Lopez, Reinhard Genzel, Guy Perrin, J. Stadler, Pierre Kervella, Karine Perraut, M. Koutoulaki, Myriam Benisty, Wolfgang Brandner, Yann Clénet, P. T. de Zeeuw, Jinyi Shangguan, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: stars, 010504 meteorology & atmospheric sciences, Stellar mass, Gaussian, Young stellar object, Overtone, FOS: Physical sciences, Astrophysics, 01 natural sciences, symbols.namesake, formation -stars, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, observational, massive -infrared, 010303 astronomy & astrophysics, infrared: stars, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, [PHYS]Physics [physics], stars: formation, Astronomy and Astrophysics, Position angle, Ellipsoid, Astrophysics - Astrophysics of Galaxies, stars: massive, Interferometry, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, techniques: interferometric, interferometric -techniques, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Closure phase, symbols, Astrophysics::Earth and Planetary Astrophysics, methods: observational, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], techniques: spectroscopic, stars -techniques, spectroscopicmethods
Abstract: The inner regions of the discs of high-mass young stellar objects (HMYSOs) are still poorly known due to the small angular scales and the high visual extinction involved. We deploy near-infrared (NIR) spectro-interferometry to probe the inner gaseous disc in HMYSOs and investigate the origin and physical characteristics of the CO bandhead emission (2.3-2.4 $\mu$m). We present the first GRAVITY/VLTI observations at high spectral (R=4000) and spatial (mas) resolution of the CO overtone transitions in NGC 2024 IRS2. The continuum emission is resolved in all baselines and is slightly asymmetric, displaying small closure phases ($\leq$8$^{\circ}$). Our best ellipsoid model provides a disc inclination of 34$^{\circ}$$\pm$1$^{\circ}$, a disc major axis position angle of 166$^{\circ}$$\pm$1$^{\circ}$, and a disc diameter of 3.99$\pm$0.09 mas (or 1.69$\pm$0.04 au, at a distance of 423 pc). The small closure phase signals in the continuum are modelled with a skewed rim, originating from a pure inclination effect. For the first time, our observations spatially and spectrally resolve the first four CO bandheads. Changes in visibility, as well as differential and closure phases across the bandheads are detected. Both the size and geometry of the CO-emitting region are determined by fitting a bidimensional Gaussian to the continuum-compensated CO bandhead visibilities. The CO-emitting region has a diameter of 2.74$\pm^{0.08}_{0.07}$ mas (1.16$\pm$0.03 au), and is located in the inner gaseous disc, well within the dusty rim, with inclination and $PA$ matching the dusty disc geometry, which indicates that both dusty and gaseous discs are coplanar. Physical and dynamical gas conditions are inferred by modelling the CO spectrum. Finally, we derive a direct measurement of the stellar mass of $M_*\sim$14.7$^{+2}_{-3.6}$ M$_{\odot}$ by combining our interferometric and spectral modelling results., Comment: Accepted for publication in A&A letters
Published: 2020

27. Peering into the formation history of β Pictoris b with VLTI/GRAVITY long-baseline interferometry

Author: Gérard Rousset, N. M. Förster Schreiber, E. F. van Dishoeck, Laurent Pueyo, Frank Eisenhauer, Pierre Léna, H. Bonnet, Jingxiu Wang, Eric Gendron, Stefan Gillessen, Anne-Lise Maire, Yann Clénet, P. T. de Zeeuw, Hervé Beust, Jinyi Shangguan, S. Yazici, Julien Woillez, Thibaut Paumard, Claudia Paladini, C. Collin, M. Nowak, Sylvestre Lacour, Thomas Ott, D. Ziegler, F. Chapron, António Amorim, Erich Wiezorrek, Oliver Pfuhl, Feng Gao, A. Buron, P. Fédou, Z. Hubert, R. Garcia Lopez, Reinhard Genzel, Wolfgang Brandner, Odele Straub, J.-B. Le Bouquin, Ekkehard Wieprecht, Jean-Phillipe Berger, Stefan Hippler, Benjamin Charnay, Eckhard Sturm, F. Vincent, Pierre Kervella, Faustine Cantalloube, Laurent Jocou, G. Rodríguez-Coira, Sebastian Rabien, Roberto Abuter, Anne-Marie Lagrange, Mickael Bonnefoy, C. Rau, Linda J. Tacconi, Guy Perrin, Andreas Eckart, Silvia Scheithauer, Felix Widmann, Karine Perraut, V. Lapeyrère, P. Mollière, Gilles Duvert, Christian Straubmeier, F. Haußmann, Th. Henning, Jason Dexter, V. Coudé du Foresto, R. Dembet, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: Planetesimal, 010504 meteorology & atmospheric sciences, planets and satellites, formation -planets and satellites, atmospheres -techniques, FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, β Pictoris, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, individual, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Orbital elements, Physics, [PHYS]Physics [physics], Earth and Planetary Astrophysics (astro-ph.EP), Very Large Telescope, Giant planet, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrometry, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics::Earth and Planetary Astrophysics, interferometricstars, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, Planetary mass, Astrophysics - Earth and Planetary Astrophysics
Abstract: Our objective is to estimate the C/O ratio in the atmosphere of beta Pictoris b and obtain an estimate of the dynamical mass of the planet, as well as to refine its orbital parameters using high-precision astrometry. We used the GRAVITY instrument with the four 8.2 m telescopes of the Very Large Telescope Interferometer to obtain K-band spectro-interferometric data on $\beta$ Pic b. We extracted a medium resolution (R=500) K-band spectrum of the planet and a high-precision astrometric position. We estimated the planetary C/O ratio using two different approaches (forward modeling and free retrieval) from two different codes (ExoREM and petitRADTRANS, respectively). Finally, we used a simplified model of two formation scenarios (gravitational collapse and core-accretion) to determine which can best explain the measured C/O ratio. Our new astrometry disfavors a circular orbit for $\beta$ Pic b ($e=0.15^{+0.05}_{-0.04}$). Combined with previous results and with Hipparcos/GAIA measurements, this astrometry points to a planet mass of $M = 12.7\pm{}2.2\,M_\mathrm{Jup}$. This value is compatible with the mass derived with the free-retrieval code petitRADTRANS using spectral data only. The forward modeling and free-retrieval approches yield very similar results regarding the atmosphere of beta Pic b. In particular, the C/O ratios derived with the two codes are identical ($0.43\pm{}0.05$ vs $0.43^{+0.04}_{-0.03}$). We argue that if the stellar C/O in $\beta$ Pic is Solar, then this combination of a very high mass and a low C/O ratio for the planet suggests a formation through core-accretion, with strong planetesimal enrichment., Comment: 14 pages + 7 page appendix, 7 figures, accepted for pulication
Published: 2020

28. The GRAVITY Young Stellar Object survey I. Probing the disks of Herbig Ae/Be stars in terrestrial orbits

Author: S. Yazici, Oliver Pfuhl, Thomas Henning, J. Bouvier, Stefan Hippler, V. Coudé du Foresto, Thomas Ott, J. Sanchez-Bermudez, Lucas Labadie, E. F. van Dishoeck, Myriam Benisty, Sebastian Rabien, Stefan Gillessen, Frank Eisenhauer, Frederic H. Vincent, A. Caratti o Garatti, Karine Perraut, Chien-Cheng Lin, Laurent Jocou, Andreas Eckart, Jaime E. Pineda, Matthew Horrobin, Christian Straubmeier, Roberto Abuter, Idel Waisberg, Feng Gao, L. Klarmann, Catherine Dougados, Imke Wank, Antoine Mérand, C. Rau, Gérard Rousset, Felix Widmann, Sarah Kendrew, Guy Perrin, A. Buron, P. T. de Zeeuw, Thomas P. Ray, R. Grellmann, Wolfgang Brandner, António Amorim, Bernard Lazareff, Dominique Segura-Cox, Paulo Gordo, Erich Wiezorrek, Henri Bonnet, F. Eupen, Eric Gendron, F. Haussmann, M. Koutoulaki, Yann Clénet, Silvia Scheithauer, Xavier Haubois, Paola Caselli, M. Wiest, Paulo J. V. Garcia, Gilles Duvert, Reinhard Genzel, Julien Woillez, Thibaut Paumard, E. Sturm, Jason Dexter, Jean-Philippe Berger, Z. Hubert, Sylvestre Lacour, Odele Straub, J.-B. Le Bouquin, Pierre Léna, R. Garcia-Lopez, Ekkehard Wieprecht, Pierre Kervella, Faustine Cantalloube, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
Subjects: stars, Young stellar object, Population, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Planet, 0103 physical sciences, Thermal, Astrophysics::Solar and Stellar Astrophysics, high angular resolutiontechniques, education, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Physics, Earth and Planetary Astrophysics (astro-ph.EP), education.field_of_study, Very Large Telescope, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), formation -circumstellar matter -infrared, interferometric, Closure phase, Terrestrial planet, Astrophysics::Earth and Planetary Astrophysics, ISM -techniques, Astrophysics - Earth and Planetary Astrophysics
Abstract: The formation and the evolution of protoplanetary disks are important stages in the lifetime of stars. The processes of disk evolution and planet formation are intrinsically linked. We spatially resolve with GRAVITY/VLTI in the K-band the sub au-scale region of 27 stars to gain statistical understanding of their properties. We look for correlations with stellar parameters, such as luminosity, mass, temperature and age. Our sample also cover a range of various properties in terms of reprocessed flux, flared or flat morphology, and gaps. We developed semi-physical geometrical models to fit our interferometric data. Our best models correspond to smooth and wide rings, implying that wedge-shaped rims at the dust sublimation edge are favored, as found in the H-band. The closure phases are generally non-null with a median value of ~10 deg, indicating spatial asymmetries of the intensity distributions. Multi-size grain populations could explain the closure phase ranges below 20-25 deg but other scenarios should be invoked to explain the largest ones. Our measurements extend the Radius-Luminosity relation to ~1e4 Lsun and confirm the significant spread around the mean relation observed in the H-band. Gapped sources exhibit a large N-to-K band size ratio and large values of this ratio are only observed for the members of our sample that would be older than 1 Ma, less massive, and with lower luminosity. In the 2 Ms mass range, we observe a correlation in the increase of the relative age with the transition from group II to group I, and an increase of the N-to-K size ratio. However, the size of the current sample does not yet permit us to invoke a clear universal evolution mechanism across the HAeBe mass range. The measured locations of the K-band emission suggest that these disks might be structured by forming young planets, rather than by depletion due to EUV, FUV, and X-ray photo-evaporation., Comment: Accepted for publication in A&A; 23 pages, 16 figures, 7 tables
Published: 2019

29. The GRAVITY young stellar object survey

Author: Paola Caselli, E. F. van Dishoeck, Feng Gao, Jaime E. Pineda, Karine Perraut, Lucas Labadie, Stefan Gillessen, Catherine Dougados, Felix Widmann, E. Sturm, Odele Straub, Eric Gendron, J.-B. Le Bouquin, Christian Straubmeier, L. Klarmann, Mercedes E. Filho, A. Eckart, Thomas Ott, J. Sanchez-Bermudez, Th. Henning, A. Drescher, V. Lapeyrère, Gérard Rousset, Zoltan Hubert, Matthew Horrobin, Paulo J. V. Garcia, Gilles Duvert, Julien Woillez, G. Heissel, Thibaut Paumard, Jean-Phillipe Berger, G. Rodríguez-Coira, R. Grellmann, Frederic H. Vincent, Laurent Jocou, J. Stadler, S. D. von Fellenberg, Sylvestre Lacour, António Amorim, Guy Perrin, Pierre Kervella, V. Coudé du Foresto, Frank Eisenhauer, R. Garcia Lopez, Reinhard Genzel, Dominique Segura-Cox, Pierre Léna, M. Bauböck, Myriam Benisty, T. Taro Shimizu, A. Caratti o Garatti, A. Jiménez-Rosales, Yann Clénet, P. T. de Zeeuw, Wolfgang Brandner, and Jinyi Shangguan
Subjects: Young stellar object, FOS: Physical sciences, Context (language use), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Angular resolution, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Very Large Telescope, 010308 nuclear & particles physics, Astronomy and Astrophysics, Accretion (astrophysics), Vortex, Stars, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract: Protoplanetary disks drive some of the formation process (e.g., accretion, gas dissipation, formation of structures, etc.) of stars and planets. Understanding such physical processes is one of the main astrophysical questions. HD 163296 is an interesting young stellar object for which infrared and sub-millimeter observations have shown a prominent circumstellar disk with gaps plausibly created by forming planets. This study aims at characterizing the morphology of the inner disk in HD 163296 with multi-epoch near-infrared interferometric observations performed with GRAVITY at the Very Large Telescope Interferometer (VLTI). Our goal is to depict the K-band (lambda_0 ~ 2.2 um) structure of the inner rim with milliarcsecond (sub-au) angular resolution. Our data is complemented with archival PIONIER (H-band; lambda_0 ~ 1.65 um) data of the source. We performed a Gradient Descent parametric model fitting to recover the sub-au morphology of our source. Our analysis shows the existence of an asymmetry in the disk surrounding the central star of HD 163296. We confirm variability of the disk structure in the inner ~2 mas (0.2 au). While variability of the inner disk structure in this source has been suggested by previous interferometric studies, this is the first time that it is confirmed in the H- and K-bands by using a complete analysis of the closure phases and squared visibilities over several epochs. Because of the separation from the star, position changes, and persistence of this asymmetric structure on timescales of several years, we argue that it is a dusty feature (e.g., a vortex or dust clouds), probably, made by a mixing of sillicate and carbon dust and/or refractory grains, inhomogeneously distributed above the mid-plane of the disk., Accepted to be published in Astronomy and Astrophysics; main-body: 11 pages, 3 figures and 3 tables
Published: 2021

30. The GRAVITY fringe tracker

Author: Christian Straubmeier, Oliver Pfuhl, Elodie Choquet, Wolfgang Brandner, Xavier Haubois, P. Fédou, Roderick Dembet, Sylvestre Lacour, Guy Perrin, Burkhard Wolff, Julien Woillez, Karine Perraut, A. Ramirez, António Amorim, Konrad R. W. Tristram, Ekkehard Wieprecht, Roberto Abuter, Frédéric Cassaing, T. Ott, Erich Wiezorrek, Frank Eisenhauer, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, University of Cambridge [UK] (CAM), European Southern Observatory (ESO), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), DOTA, ONERA, Université Paris Saclay [Châtillon], ONERA-Université Paris-Saclay, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Universität zu Köln, Max-Planck-Institut für Astronomie (MPIA), SIM/IDL Faculdade de Ciências da Universidade de Lisboa (FCUL), University of Lisboa, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), DOTA, ONERA, Université Paris Saclay (COmUE) [Châtillon], ONERA-Université Paris Saclay (COmUE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Universität zu Köln = University of Cologne
Subjects: Time delay and integration, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Context (language use), Astrophysics, Tracking (particle physics), 01 natural sciences, Optics, Optical path, Control theory, 0103 physical sciences, instrumentation: interferometers, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Physics, business.industry, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, techniques: high angular resolution, Astronomy and Astrophysics, Kalman filter, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Space and Planetary Science, Integrator, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Instrumentation and Methods for Astrophysics, business
Abstract: The GRAVITY instrument has been commissioned on the VLTI during 2016 and is now available to the astronomical community. It is the first optical interferometer capable of observing sources as faint as magnitude 19 in K-band. This is possible thanks to the fringe tracker which compensates the differential piston based on measurements of a brighter off-axis astronomical reference source. The goal of this paper is to consign the main developments made in the context of the GRAVITY fringe tracker. This could serve as basis for future fringe tracking systems. The paper therefore covers all aspects of the fringe tracker, from hardware, to control software and on-sky observations. Special emphasis is placed on the interaction between the group delay controller and the phase delay controller. The group delay control loop is a simple but robust integrator. The phase delay controller is a state-space control loop based on an auto-regressive representation of the atmospheric and vibrational perturbations. A Kalman filter provides optimal determination of the state of the system. The fringe tracker shows good tracking performance on sources with coherent K magnitudes of 11 on the UTs and 9.5 on the ATs. It can track fringes with an SNR level of 1.5 per DIT, limited by photon and background noises. On the ATs, during good seeing conditions, the optical path delay residuals can be as low as 75 nm root mean square. On the UTs, the performance is limited to around 250 nm because of structural vibrations., Accepted in A&A. 18 pages
Published: 2019

31. Scalar field effects on the orbit of S2 star

Author: Andreas Eckart, A. Jiménez-Rosales, Thibaut Paumard, Odele Straub, J.-B. Le Bouquin, V. Coudé Du Forest, Eckhard Sturm, Feng Gao, Maryam Habibi, Pierre Kervella, T. de Zeeuw, G. Rodriguez Coira, Jason Dexter, Laurent Jocou, Idel Waisberg, Myriam Benisty, Oliver Pfuhl, T. Ott, Christian Straubmeier, António Amorim, Paulo Gordo, Frank Eisenhauer, S. von Fellenberg, Pierre Léna, M. Bauböck, M. Pössel, Gilles Duvert, Sylvestre Lacour, Stefan Gillessen, Jean-Philippe Berger, R. Genzel, Yann Clénet, G. Rousset, F. Vincent, Paulo J. V. Garcia, Karine Perraut, Guy Perrin, Felix Widmann, M. Ferreira, Eric Gendron, Matthew Horrobin, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), GRAVITY, Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Field (physics), Dark matter, black hole physics, FOS: Physical sciences, torus, General Relativity and Quantum Cosmology (gr-qc), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Compact star, mass: scalar, 01 natural sciences, General Relativity and Quantum Cosmology, dark matter, Gravitation, precession, black hole: Kerr, energy: rotation, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, central region, Astronomy and Astrophysics, hair, star: orbit, celestial mechanics, Astrophysics - Astrophysics of Galaxies, mass: coupling, Galaxy: centre, Galaxy, field theory: scalar, Black hole, Rotating black hole, 13. Climate action, Space and Planetary Science, gravitation, Astrophysics of Galaxies (astro-ph.GA), [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], galaxy, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Scalar field, superradiance, signature
Abstract: Precise measurements of the S-stars orbiting SgrA* have set strong constraints on the nature of the compact object at the centre of the Milky Way. The presence of a black hole in that region is well established, but its neighboring environment is still an open debate. In that respect, the existence of dark matter in that central region may be detectable due to its strong signatures on the orbits of stars: the main effect is a Newtonian precession which will affect the overall pericentre shift of S2, the latter being a target measurement of the GRAVITY instrument. The exact nature of this dark matter (e.g., stellar dark remnants or diffuse dark matter) is unknown. This article assumes it to be an scalar field of toroidal distribution, associated with ultra-light dark matter particles, surrounding the Kerr black hole. Such a field is a form of "hair" expected in the context of superradiance, a mechanism that extracts rotational energy from the black hole. Orbital signatures for the S2 star are computed and shown to be detectable by GRAVITY. The scalar field can be constrained because the variation of orbital elements depends both on the relative mass of the scalar field to the black hole and on the field mass coupling parameter., Comment: 17 pages, 6 figures. v2: added some references and fixed minor typos to match version in press in MNRAS
Published: 2019

32. Test of the Einstein Equivalence Principle near the Galactic Center Supermassive Black Hole

Author: N. M. Förster Schreiber, Karine Perraut, Ekkehard Wieprecht, Christian Straubmeier, Stefan Hippler, Th. Henning, Thibaut Paumard, Frank Eisenhauer, Felix Widmann, Pierre Kervella, Laurent Jocou, Paulo J. V. Garcia, Pierre Léna, Silvia Scheithauer, Matthew Horrobin, M. Bauböck, Thomas Ott, Maryam Habibi, Oliver Pfuhl, Jason Dexter, Linda J. Tacconi, S. von Fellenberg, A. Jimenez Rosales, Yann Clénet, P. T. de Zeeuw, Sylvestre Lacour, Gilles Duvert, Andreas Eckart, Guy Perrin, Amiel Sternberg, Senol Yazici, Eckhard Sturm, Erich Wiezorrek, Eric Gendron, Idel Waisberg, M. Ebert, Reinhard Genzel, F. Vincent, António Amorim, Sebastian Rabien, G. Rodríguez-Coira, Z. Hubert, Xavier Haubois, Vincent Lapeyrere, Odele Straub, J.-B. Le Bouquin, Wolfgang Brandner, G. Rousset, Feng Gao, V. Coudé du Foresto, Jean-Philippe Berger, Stefan Gillessen, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), GRAVITY, Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: General Physics and Astronomy, FOS: Physical sciences, Astrophysics, General Relativity and Quantum Cosmology (gr-qc), Gravitation and Astrophysics, 7. Clean energy, 01 natural sciences, General Relativity and Quantum Cosmology, Gravitational potential, 0103 physical sciences, Equivalence principle, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, Supermassive black hole, Galactic Center, White dwarf, Astrophysics - Astrophysics of Galaxies, Redshift, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], Black hole, Sagittarius A, Astrophysics of Galaxies (astro-ph.GA), Physics::Space Physics, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: During its orbit around the four million solar mass black hole Sagittarius A* the star S2 experiences significant changes in gravitational potential. We use this change of potential to test one part of the Einstein equivalence principle: the local position invariance (LPI). We study the dependency of different atomic transitions on the gravitational potential to give an upper limit on violations of the LPI. This is done by separately measuring the redshift from hydrogen and helium absorption lines in the stellar spectrum during its closest approach to the black hole. For this measurement we use radial velocity data from 2015 to 2018 and combine it with the gravitational potential at the position of S2, which is calculated from the precisely known orbit of S2 around the black hole. This results in a limit on a violation of the LPI of $|\beta_{He}-\beta_{H}| = (2.4 \pm 5.1) \cdot 10^{-2}$. The variation in potential that we probe with this measurement is six magnitudes larger than possible for measurements on Earth, and a factor ten larger than in experiments using white dwarfs. We are therefore testing the LPI in a regime where it has not been tested before., Comment: Accepted for publication in Physical Review Letters
Published: 2019

33. A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty

Author: Idel Waisberg, Thibaut Paumard, Julien Woillez, Jason Dexter, Oliver Pfuhl, Stefan Gillessen, Thomas Henning, Senol Yazici, Matthew Horrobin, Stefan Hippler, Christian Straubmeier, Karine Perraut, Odele Straub, J.-B. Le Bouquin, Sebastian Rabien, Amiel Sternberg, F. Vincent, António Amorim, Laurent Jocou, Vincent Lapeyrere, Reinhard Genzel, V. Coudé du Foresto, Feng Gao, Xavier Haubois, Gilles Duvert, Ekkehard Wieprecht, Jean-Philippe Berger, Paulo J. V. Garcia, Maryam Habibi, Thomas Ott, A. Jiménez-Rosales, Ortwin Gerhard, S. von Fellenberg, Linda J. Tacconi, G. Rousset, Eric Gendron, Guy Perrin, Pierre Kervella, Frank Eisenhauer, G. Rodriguez Coira, R. Abuter, Felix Widmann, Pierre Léna, Eckhard Sturm, Silvia Scheithauer, N. M. Förster Schreiber, Erich Wiezorrek, Henri Bonnet, Andreas Eckart, M. Bauböck, Sylvestre Lacour, Yann Clénet, P. T. de Zeeuw, Wolfgang Brandner, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Galaxy: nucleus, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Galactic Center, black hole physics, FOS: Physical sciences, Astronomy and Astrophysics, Orbital eccentricity, Astrometry, Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Redshift, Black hole, Orbit, Interferometry, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, astrometry, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Gravitational redshift
Abstract: We present a 0.16% precise and 0.27% accurate determination of R0, the distance to the Galactic Center. Our measurement uses the star S2 on its 16-year orbit around the massive black hole Sgr A* that we followed astrometrically and spectroscopically for 27 years. Since 2017, we added near-infrared interferometry with the VLTI beam combiner GRAVITY, yielding a direct measurement of the separation vector between S2 and Sgr A* with an accuracy as good as 20 micro-arcsec in the best cases. S2 passed the pericenter of its highly eccentric orbit in May 2018, and we followed the passage with dense sampling throughout the year. Together with our spectroscopy, in the best cases with an error of 7 km/s, this yields a geometric distance estimate: R0 = 8178 +- 13(stat.) +- 22(sys.) pc. This work updates our previous publication in which we reported the first detection of the gravitational redshift in the S2 data. The redshift term is now detected with a significance level of 20 sigma with f_redshift = 1.04 +- 0.05., Comment: 9 pages, 7 figures, submitted to A&A
Published: 2019
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34. An image of the dust sublimation region in the nucleus of NGC 1068

Author: Sebastian F. Hönig, António Amorim, Idel Waisberg, N. M. Förster Schreiber, Feng Gao, Wolfgang Brandner, Paulo J. V. Garcia, T. Taro Shimizu, Linda J. Tacconi, Amiel Sternberg, D. Gratadour, Guy Perrin, Konrad R. W. Tristram, Jason Dexter, Felix Widmann, Andreas Eckart, Mercedes Prieto, P.-O. Petrucci, Bradley M. Peterson, Karine Perraut, Oliver Pfuhl, Sylvestre Lacour, Eckhard Sturm, Frank Eisenhauer, Julien Woillez, Stefan Gillessen, Ric Davies, Jinyi Shangguan, Odele Straub, Dieter Lutz, Makoto Kishimoto, Yann Clénet, P. T. de Zeeuw, Hagai Netzer, P. Vermot, Thibaut Paumard, Thomas Ott, Florentin Millour, Daniel Rouan, Marc Schartmann, Reinhard Genzel, Christian Straubmeier, Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)
Subjects: 010504 meteorology & atmospheric sciences, galaxies: active, FOS: Physical sciences, Astrophysics, 01 natural sciences, Observatory, 0103 physical sciences, medicine, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Physics, Very Large Telescope, Astronomy and Astrophysics, Position angle, Astrophysics - Astrophysics of Galaxies, Galaxy, galaxies: Seyfert, Interferometry, medicine.anatomical_structure, Space and Planetary Science, techniques: interferometric, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Sublimation (phase transition), galaxies: nuclei, Nucleus
Abstract: We present near-infrared interferometric data on the Seyfert 2 galaxy NGC 1068, obtained with the GRAVITY instrument on the European Southern Observatory Very Large Telescope Interferometer. The extensive baseline coverage from 5 to 60 M\lambda allowed us to reconstruct a continuum image of the nucleus with an unrivaled 0.2 pc resolution in the K-band. We find a thin ring-like structure of emission with a radius r = 0.24+/-0.03 pc, inclination i = 70+/-5 deg, position angle PA = -50+/-4 deg, and h/r < 0.14, which we associate with the dust sublimation region. The observed morphology is inconsistent with the expected signatures of a geometrically and optically thick torus. Instead, the infrared emission shows a striking resemblance to the 22 GHz maser disc, which suggests they share a common region of origin. The near-infrared spectral energy distribution indicates a bolometric luminosity of (0.4-4.7) x 10^45 erg/s, behind a large A_K ~ 5.5 (A_V ~ 90) screen of extinction that also appears to contribute significantly to obscuring the broad line region., Comment: Accepted for publication in Astronomy and Astrophysics. 13 pages with 7 figures
Published: 2019
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35. Central kiloparsec of NGC 1326 observed with SINFONI

Author: Gerold Busch, Persis Misquitta, Francoise Combes, Andreas Eckart, Nastaran Fazeli, and Christian Straubmeier
Subjects: Physics, Luminous infrared galaxy, 010308 nuclear & particles physics, Space and Planetary Science, 0103 physical sciences, Astronomy and Astrophysics, Astrophysics, Ring (chemistry), 010303 astronomy & astrophysics, 01 natural sciences
Abstract: Gas inflow processes in the vicinity of galactic nuclei play a crucial role in galaxy evolution and supermassive black hole growth. Exploring the central kiloparsec of galaxies is essential to shed more light on this subject. We present near-infraredH- andK-band results of the nuclear region of the nearby galaxy NGC 1326, observed with the integral-field spectrograph SINFONI mounted on the Very Large Telescope. The field of view covers 9″ × 9″ (650 × 650 pc2). Our work is concentrated on excitation conditions, morphology, and stellar content. The nucleus of NGC 1326 was classified as a LINER, however in our data we observed an absence of ionised gas emission in the centralr ∼ 3″. We studied the morphology by analysing the distribution of ionised and molecular gas, and thereby detected an elliptically shaped, circum-nuclear star-forming ring at a mean radius of 300 pc. We estimate the starburst regions in the ring to be young with dominating ages of < 10 Myr. The molecular gas distribution also reveals an elongated east to west central structure about 3″ in radius, where gas is excited by slow or mild shock mechanisms. We calculate the ionised gas mass of 8 × 105M⊙completely concentrated in the nuclear ring and the warm molecular gas mass of 187M⊙, from which half is concentrated in the ring and the other half in the elongated central structure. The stellar velocity fields show pure rotation in the plane of the galaxy. The gas velocity fields show similar rotation in the ring, but in the central elongated H2structure they show much higher amplitudes and indications of further deviation from the stellar rotation in the central 1″ aperture. We suggest that the central 6″ elongated H2structure might be a fast-rotating central disc. The CO(3–2) emission observations with the Atacama Large Millimeter/submillimeter Array reveal a central 1″ torus. In the central 1″ of the H2velocity field and residual maps, we find indications for a further decoupled structure closer to a nuclear disc, which could be identified with the torus surrounding the supermassive black hole.
Published: 2020

36. A Faint Near-Infrared/Radio Flare form SgrA

Author: M. Valencia-S., Anton Zensus, E. Hosseini, N. Sabha, Christian Straubmeier, Nastaran Fazeli, Vladimír Karas, A. Borkar, Gerold Busch, M. Subroweit, Michal Zajaček, Banafsheh Shahzamanian, Shogo Nishiyama, A. Eckart, M. Parsa, F. Peissker, K. Markakis, Silke Britzen, Lukas Steiniger, and Andreas Eckart
Subjects: Physics, Astrophysics::High Energy Astrophysical Phenomena, Near-infrared spectroscopy, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Synchrotron, Magnetic field, law.invention, Telescope, Interferometry, law, Astrophysics::Solar and Stellar Astrophysics, Subaru Telescope, Adaptive optics, Astrophysics::Galaxy Astrophysics, Flare
Abstract: During the past decades the analysis of flare emission from Sgr A* helped to put constraints on the emission models and the corresponding physical parameters. In the NIR the source is characterized by a single power-law flux density distribution. There is also evidence for the fact that radio and NIR variability data are described by a single power-law state with a power-law index of 4 similar to the one in the NIR. Here we summarize results of an analysis of NIR Ks-band data taken in the NIR using the High-contrast Coronographic Imager for Adaptive Optics (HiCIAO) at the SUBARU Telescope in May 2012. These observations partially overlap in time with radio data taken with the Australia Telescope Compact Array (ATCA) interferometer. The results are discussed in the framework of adiabatically expanding synchrotron sources as well as the possibility of quasi-simultaneous flare emission at both frequencies. The analysis has also been applied to other NIR/radio flares. The magnetic fields that we derive are in the range of a few to about 30 Gauss.
Published: 2018

37. Detection of orbital motions near the last stable circular orbit of the massive black hole SgrA*

Author: Linda J. Tacconi, Eckhard Sturm, Laurent Jocou, Julien Woillez, Guy Perrin, Bernard Lazareff, Christian Straubmeier, P. M. Plewa, Stefan Hippler, H. Bonnet, Feng Gao, Eric Gendron, Th. Henning, Gérard Rousset, N. M. Förster Schreiber, Thomas Ott, Johana Panduro, Jean-Philippe Berger, P. Guajardo, Frank Eisenhauer, Karine Perraut, S. von Fellenberg, Yann Clénet, P. T. de Zeeuw, Felix Widmann, Pierre Léna, Thibaut Paumard, Oliver Pfuhl, Xavier Haubois, Erich Wiezorrek, V. Coudé du Foresto, Casey Deen, Sylvestre Lacour, Stefan Gillessen, Jason Dexter, Amiel Sternberg, Gilles Duvert, Matthew Horrobin, Odele Straub, J.-B. Le Bouquin, Armin Huber, Reinhard Genzel, Paulo J. V. Garcia, Sebastian Rabien, António Amorim, G. Rodríguez-Coira, Wolfgang Brandner, Frederic H. Vincent, Roberto Abuter, V. Lapeyrère, Idel Waisberg, Andreas Eckart, S. Yazici, Maryam Habibi, M. Bauböck, Pierre Kervella, Magdalena Lippa, A. Jiménez-Rosales, Ekkehard Wieprecht, European Southern Observatory (ESO), Max-Planck-Institut für Astronomie (MPIA), Max-Planck-Gesellschaft, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Radioastronomie (MPIFR), Max Planck Institute for Extraterrestrial Physics (MPE), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris - Site de Paris (OP), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Transport et Environnement (INRETS/LTE), Institut National de Recherche sur les Transports et leur Sécurité (INRETS), Institut de biologie et chimie des protéines [Lyon] (IBCP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Swedish Space Corporation (SSC), School of Physics and Astronomy [Tel Aviv], Tel Aviv University [Tel Aviv], Laboratoire Univers et Théories (LUTH (UMR_8102)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, Universität zu Köln, AUTRES, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)
Subjects: Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, Gravitation, Telescope, General Relativity and Quantum Cosmology, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Circular orbit, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Physics, [PHYS]Physics [physics], Solar mass, 010308 nuclear & particles physics, Astronomy and Astrophysics, Polarization (waves), Astrophysics - Astrophysics of Galaxies, Interferometry, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Orbital motion, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Schwarzschild radius
Abstract: We report the detection of continuous positional and polarization changes of the compact source SgrA* in high states ('flares') of its variable near- infrared emission with the near-infrared GRAVITY-Very Large Telescope Interferometer (VLTI) beam-combining instrument. In three prominent bright flares, the position centroids exhibit clockwise looped motion on the sky, on scales of typically 150 micro-arcseconds over a few tens of minutes, corresponding to about 30% the speed of light. At the same time, the flares exhibit continuous rotation of the polarization angle, with about the same 45(+/-15)-minute period as that of the centroid motions. Modelling with relativistic ray tracing shows that these findings are all consistent with a near face-on, circular orbit of a compact polarized 'hot spot' of infrared synchrotron emission at approximately six to ten times the gravitational radius of a black hole of 4 million solar masses. This corresponds to the region just outside the innermost, stable, prograde circular orbit (ISCO) of a Schwarzschild-Kerr black hole, or near the retrograde ISCO of a highly spun-up Kerr hole. The polarization signature is consistent with orbital motion in a strong poloidal magnetic field., Comment: accepted by A&A; 16 pages
Published: 2018

38. End to end optical design and wavefront error simulation of METIS

Author: Stephen P. Todd, Christian Straubmeier, Nicola Baccichet, M. Concepcion Cardenas Vazquez, Sara Zuccon, Rik ter Horst, Joost van den Born, Tibor Agócs, Willem Jellema, and Peter Bizenberger
Subjects: 010309 optics, End-to-end principle, Computer science, 0103 physical sciences, Astrophysics::Instrumentation and Methods for Astrophysics, Metis, Electronic engineering, Physics::Optics, Adaptive optics, 010303 astronomy & astrophysics, 01 natural sciences
Abstract: We present the preliminary optical design of METIS, the Mid-infrared E-ELT Imager and Spectrograph, and study the end-to-end performance regarding wavefront errors and non-common path aberrations. We discuss the results of the Monte Carlo simulations that contain the manufacturing and alignment errors of the opto-mechanical system. We elaborate on the wavefront error budget of the instrument detailing all contributors. We investigate the mid and high spatial frequency errors of the optical surfaces, which we model using simulated surface height errors maps of one dimensional Power Spectral Density (PSD) functions.
Published: 2018

39. The calibration unit of the mid-infrared E-ELT instrument METIS

Author: Christian Straubmeier, Nicola Baccichet, Adrian M. Glauser, Leonard Burtscher, Andreas Eckart, M. Wiest, Willem Jellema, Roy van Boekel, Lucas Labadie, Jeffrey Lynn, Tibor Agócs, Ronald Roelfsema, Steffen Rost, Felix Bettonvil, and Bernhard R. Brandl
Subjects: Cryostat, High fidelity, Integrating sphere, Computer science, Metis, Electronic engineering, Phase (waves), Calibration, Focus (optics), Common emitter
Abstract: We present the preliminary design of the calibration unit of the future E-ELT instrument METIS. This independent subunit is mounted externally to the main cryostat of METIS and will function both as calibration reference for science observations, as well as verification and alignment tool during the AIT phase. In this paper, we focus on describing its preliminary layout and foreseen functionalities, based on the performance requirements defined at system level and the constraints imposed by warm IR background. We discuss the advantage of employing an integrating sphere as common radiation emitter, leading to a novel and versatile design, where the source's spatio-spectral properties can be varied with high fidelity and repeatability. By combining only few tuneable sources and mechanisms we show how a large instrument such as METIS can be calibrated and tested, without the need of a complex cold calibration unit.
Published: 2018

40. Data reduction of the VLTI/GRAVITY interferometric instrument (Conference Presentation)

Author: Jean-Baptiste Le Bouquin, Cesar Enrique Garcia-Dabo, Pierre Kervella, Frank Eisenhauer, Sylvestre Lacour, Antoine Mérand, Julien Woillez, António Amorim, Guy Perrin, Karine Perraut, Christian Straubmeier, Wolfgang Brandner, and V. Lapeyrere
Subjects: Physics, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Phase (waves), Astrometry, Interference (wave propagation), Metrology, law.invention, Telescope, Interferometry, Optics, law, Calibration, business, Data reduction
Abstract: The new VLTI/GRAVITY instrument is a four telescope beam combiner installed at the VLT Interferometer. The principal novelty of this instrument is the availability of a dual field mode enabling narrow-angle relative astrometry at micro-arcsecond accuracy between two objects separated by several arcseconds. The fringe tracker (FT) stabilizes the interference fringes at up to 1 kHz frequency, allowing for long exposures with the science combiner (SC) as well as phase referenced imaging and differential astrometry (in dual field mode). The FT and SC beam combiners are integrated optics (IO) components, whose 24 outputs are (optionally) polarization-split and spectrally dispersed. The processing of the photometric signals from the IO components is based on the pixel-to-visibility matrix (P2VM) formalism, that translates them into complex visibilities. The retrieval of the relative phase of the two objects subsequently relies on the combination of the phases measured from the FT, SC and the laser metrology. We will present the adopted algorithms, and an overview of the structure of the developed software. The calibration of the wavelength scales of the FT and SC at the required accuracy presents specific difficulties that we will briefly discuss. Examples of the reduction of on-sky data obtained during the commissioning will also be presented.
Published: 2018

41. The warm calibration unit of METIS: optical design and principle of operation

Author: Jeffrey Lynn, Bernhard R. Brandl, Ronald Roelfsema, Felix Bettonvil, Christian Straubmeier, Nicola Baccichet, M. Wiest, Tibor Agócs, Andreas Eckart, Lucas Labadie, and Steffen Rost
Subjects: Scientific instrument, Design phase, Optical path, Instrumentation, Extremely Large Telescope, Metis, Calibration, Spectrograph, Remote sensing
Abstract: METIS, a mid-infrared imager and spectrograph for the wavelength range 2.9–19μm (astronomical L-, M-, N- and Q-band), will be one of the first three science instruments at the European Extremely Large Telescope (E-ELT). It will provide diffraction limited imaging, coronagraphy, high resolution integral field spectroscopy and low and medium resolution slit spectroscopy. Within the international METIS consortium, the 1st Institute of Physics of the University of Cologne in Germany is responsible for the design, manufacturing, integration and qualification of the Warm Calibration Unit (WCU) of the instrument. The WCU will be a self-contained unit operating at ambient temperature outside of the voluminous METIS dewar, feeding a variety of optical calibration and alignment signals into the optical path of METIS. The functionalities of the WCU will be used for routine daily daytime calibrations after astronomical observing nights and verification of the internal alignment of METIS during assembly, integration and verification (AIV). In this contribution we present the preliminary optical design and principle of operation of the WCU in its current state of the preliminary design phase of METIS.
Published: 2018

42. Correction of differential chromatic dispersion in GRAVITY

Author: Roderick Dembet, Sylvestre Lacour, Burkhard Wolff, Karine Rousselet-Perraut, Christian Straubmeier, Frank Eisenhauer, António Amorim, Vincent Lapeyrere, Wolfgang Brandner, Jean-Baptiste Le Bouquin, Guy Perrin, and Xavier Haubois
Subjects: Wavefront, Physics, Optical fiber, Physics::Instrumentation and Detectors, business.industry, Detector, Astrophysics::Instrumentation and Methods for Astrophysics, law.invention, Interferometry, Optics, law, Dispersion (optics), Chromatic scale, business, Optical path length, Data reduction
Abstract: The GRAVITY instrument installed at VLTI uses differential fibered delay lines to spatially filter the incoming wavefronts and accurately control the optical path difference between the Fringe Tracker (FT) and Scientific Detector (SC) parts of the instrument. On top of the differential dispersion occurring in the air, the chromatic dispersion introduced by these fibers impacts the real time performances of the fringe tracker by generating a second-order chromatic phase shift. Moreover, differential dispersion also affects GRAVITY dual-feed measurements that require a length adjustment of both FT and SC fibers. In this contribution, we show how chromatic dispersion can be corrected both in the fringe tracker real-time control as well as in the astrometric data reduction.
Published: 2018

43. The GRAVITY fringe tracker: correlation between optical path residuals and atmospheric parameters

Author: Christian Straubmeier, Sylvestre Lacour, Roderick Dembet, Wolfgang Brandner, Guy Perrin, Pierre Fedou, Roberto Abuter, Karine Perraut, António Amorim, and Frank Eisenhauer
Subjects: Physics, Correlation, Coherence time, Gravity (chemistry), Interferometry, Optical path, FOS: Physical sciences, Astrophysics - Instrumentation and Methods for Astrophysics, Tracking (particle physics), Geodesy, Instrumentation and Methods for Astrophysics (astro-ph.IM), Uncorrelated
Abstract: After the first year of observations with the GRAVITY fringe tracker, we compute correlations between the optical path residuals and atmospheric and astronomical parameters. The median residuals of the optical path residuals are 180 nm on the ATs and 270 nm on the UTs. The residuals are uncorrelated with the target magnitudes for Kmag below 5.5 on ATs (9 on UTs). The correlation with the coherence time is however extremely clear, with a drop-off in fringe tracking performance below 3 ms., Comment: submitted to SPIE Astronomical Telescopes & Instrumentation 2018
Published: 2018

44. Improving GRAVITY towards observations of faint targets

Author: Markus Schöller, P. M. Plewa, Oliver Pfuhl, Felix Widmann, Wolfgang Brandner, Christian Straubmeier, Feng Gao, Stefan Gillessen, Reinhard Genzel, Sylvestre Lacour, M. Karl, Guy Perrin, Frank Eisenhauer, António Amorim, Karin Perraut, Magdalena Lippa, Idel Waisberg, and Thomas Ott
Subjects: Physics, Gravity (chemistry), Very Large Telescope, 010308 nuclear & particles physics, Galactic Center, First light, Astrophysics, 01 natural sciences, Black hole, Interferometry, Sagittarius A, 0103 physical sciences, 010303 astronomy & astrophysics, Data reduction
Abstract: Since its first light at the Very Large Telescope Interferometer (VLTI), GRAVITY has reached new regimes in optical interferometry, in terms of accuracy as well as sensitivity. 1 GRAVITY is routinely doing phase referenced interferometry of objects fainter than K > 17 mag, which makes for example the galactic center black hole Sagittarius A* 2 detectable 90 % of the times. However from SNR calculations we are confident that even a sensitivity limit of K ~ 19 mag is possible. We therefore try to push the limits of GRAVITY by improving the observations as well as the calibration and the data reduction. This has further improved the sensitivity limit to K > 18 mag in the beginning of this year. Here we present some work we are currently doing in order to reach the best possible sensitivity.
Published: 2018

45. The Multifrequency Behavior of Sagittarius A*

Author: F. Peissker, Banafsheh Shahzamanian, Gerold Busch, Matthew Horrobin, Vladimir Karas, Steffen Rost, Andreas Eckart, Christian Straubmeier, N. Sabha, M. Subroweit, A. Borkar, Monica Valencia-S., Silke Britzen, F. Kamali, Anton Zensus, J. Schneeloch, and Nastaran Fazeli
Subjects: Physics, Supermassive black hole, Star formation, Astrophysics::High Energy Astrophysical Phenomena, Galactic Center, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Light curve, Luminosity, Stars, Sagittarius A, Galaxy formation and evolution, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: The Galactic Center is the closest galactic nucleus that allows us to determine the multi-frequency behavior of the supermassive black hole counterpart Sagittarius A* in great detail. We put SgrA*, as a nucleus with weak activity, into the context of nearby low luminosity nuclei. Possible hints for galaxy evolution of these sources across the [NII]-based diagnostic diagram can be inferred from dependencies on the masses, excitation ratios, and radio luminosities within this diagram. For SgrA* we also discuss responsible radiation mechanisms covering results from the radio, infrared, and X-ray regime. We also address the question of justifying the hot-spot model for describing flare profiles in light curves. Since the brightness of LLAGN is also linked to star formation we briefly discuss the possibility of having stars formed in the immediate vicinity of supermassive black holes and possibly even in a mildly relativistic environment.
Published: 2018

46. Learnings from the use of fiber optics in GRAVITY

Author: Erich Wiezorrek, A. Buron, Guy Perrin, Sylvestre Lacour, Thomas Ott, Frank Eisenhauer, Nicolas Blind, F. Haußmann, Laurent Jocou, Ekkehard Wieprecht, António Amorim, Markus Plattner, Oliver Pfuhl, Stefan Gillessen, Reinhard Genzel, Karine Perraut, C. Rau, O. Hans, M. Haug, Christian Straubmeier, Magdalena Lippa, Yitping Kok, Stefan Kellner, Eckhard Sturm, and Wolfgang Brandner
Subjects: Physics, Optical fiber, business.industry, Scattering, Physics::Optics, Ranging, Inelastic scattering, Polarization (waves), law.invention, Astronomical instrumentation, Metrology, Optics, law, High transmission, business
Abstract: The use of optical fibers in astronomical instrumentation has been becoming more and more common. High transmission, polarization control, compact and easy routing are just a few of the advantages in this respect. But fibers also bring new challenges for the development of systems. During the assembly of the VLTI beam combiner GRAVITY different side effects of the fiber implementation had to be taken into account. In this work we summarize the corresponding phenomena ranging from the external factors influencing the fiber performance, like mechanical and temperature effects, to inelastic scattering within the fiber material.
Published: 2018

47. Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole

Author: R.-R. Rohloff, Andreas Eckart, Sarah Kendrew, Maryam Habibi, Joany Andreina Manjarres Ramos, S. Kellner, Nicolas Blind, D. Ziegler, Wolfgang Brandner, Casey Deen, Bernard Lazareff, Jean-Philippe Berger, Gérard Zins, M. Haug, A. Ramirez, Eric Gendron, F. Haußmann, Thomas Ott, E. Müler, Silvia Scheithauer, Jason Spyromilio, Andreas Kaufer, Xavier Haubois, Markus Schöller, Eckhard Sturm, C. Collin, Stefan Hippler, Laurent Jocou, Myriam Benisty, Julien Woillez, Linda J. Tacconi, A. Buron, Imke Wank, S. von Fellenberg, M. Wiest, Paulo Gordo, Luca Pasquini, Pierre Kervella, L. Palanca, Magdalena Lippa, Martin Kulas, Roderick Dembet, Gilles Duvert, Z. Hubert, Jason Dexter, Yann Clénet, P. T. de Zeeuw, C. Rau, A. Jimenez Rosales, H. Bonnet, Sylvestre Lacour, Guy Perrin, Odele Straub, P. Fédou, J.-B. Le Bouquin, Christian Straubmeier, S. Yazici, Ekkehard Wieprecht, Gérard Rousset, V. Lapeyrère, N. M. Förster Schreiber, Sebastian Rabien, Felix Widmann, Th. Henning, F. Delplancke-Ströbele, M. Bauböck, F. Chapron, Frank Eisenhauer, Gert Finger, R. Garcia Lopez, G. Rodríguez-Coira, Reinhard Genzel, Frederic H. Vincent, Pierre Léna, Thibaut Paumard, Narsireddy Anugu, Idel Waisberg, J. Sanchez-Bermudez, N. Schuler, Karine Perraut, P. M. Plewa, Paulo J. V. Garcia, António Amorim, Yitping Kok, Oliver Pfuhl, Lieselotte Jochum, V. dCoudé u Foresto, Matthew Horrobin, Udo Neumann, Rainer Lenzen, Erich Wiezorrek, Antoine Mérand, Konrad R. W. Tristram, Norbert Hubin, Feng Gao, Stefan Gillessen, Roberto Abuter, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), GRAVITY, Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)
Subjects: General relativity, black hole physics, FOS: Physical sciences, Astrophysics, Physics - Classical Physics, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, General Relativity and Quantum Cosmology, Gravitation, Gravitational field, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, Very Large Telescope, Galaxy: center, 010308 nuclear & particles physics, Classical Physics (physics.class-ph), Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], Black hole, Space and Planetary Science, gravitation, Astrophysics of Galaxies (astro-ph.GA), [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Schwarzschild radius, Gravitational redshift
Abstract: The highly elliptical, 16-year-period orbit of the star S2 around the massive black hole candidate Sgr A* is a sensitive probe of the gravitational field in the Galactic centre. Near pericentre at 120 AU, ~1400 Schwarzschild radii, the star has an orbital speed of ~7650 km/s, such that the first-order effects of Special and General Relativity have now become detectable with current capabilities. Over the past 26 years, we have monitored the radial velocity and motion on the sky of S2, mainly with the SINFONI and NACO adaptive optics instruments on the ESO Very Large Telescope, and since 2016 and leading up to the pericentre approach in May 2018, with the four-telescope interferometric beam-combiner instrument GRAVITY. From data up to and including pericentre, we robustly detect the combined gravitational redshift and relativistic transverse Doppler effect for S2 of z ~ 200 km/s / c with different statistical analysis methods. When parameterising the post-Newtonian contribution from these effects by a factor f, with f = 0 and f = 1 corresponding to the Newtonian and general relativistic limits, respectively, we find from posterior fitting with different weighting schemes f = 0.90 +/- 0.09 (stat) +\- 0.15 (sys). The S2 data are inconsistent with pure Newtonian dynamics., Comment: Accepted for publication in A&A Letters, 29 June 2018, 10 pages, 6 figures, corresponding author: F. Eisenhauer
Published: 2018

48. GRAVITY chromatic imaging of η Car's core. Milliarcsecond resolution imaging of the wind-wind collision zone (Brγ, He I)

Author: S. Kellner, Pierre Kervella, Faustine Cantalloube, Johana Panduro, Magdalena Lippa, V. Coudé du Foresto, Y. Clénet, R. Abuter, G. Avila, Matteo Accardo, Konrad R. W. Tristram, Dan Popovic, Alejandra Rosales, A. Buron, R. Genzel, C. Deen, Laurent Jocou, Markus Schöller, T. Ott, H. Bonnet, P. Fédou, Frank Eisenhauer, R. van Boekel, Stefan Hippler, André Müller, Pierre Léna, Thibaut Moulin, Julien Woillez, L. Pallanca, Ekkehard Wieprecht, P.-O. Petrucci, N. Hubin, Leander Mehrgan, Sylvestre Lacour, Markus Wittkowski, Vincent Lapeyrere, Christian A. Hummel, M. Haug, Eckhard Sturm, Frederic Derie, Thanh Phan Duc, Sarah Kendrew, Burkhard Wolff, Mario Kiekebusch, Nicolas Blind, Andreas Kaufer, W. J. de Wit, Feng Gao, C. Collin, Silvia Scheithauer, L. Kern, Roderick Dembet, Matthew Horrobin, J.-U. Pott, Stefan Gillessen, Johann Kolb, Narsireddy Anugu, R.-R. Rohloff, M. Riquelme, J. Sanchez-Bermudez, Andreas Eckart, J. Moreno-Ventas, R. Brast, Z. Hubert, Isabelle Percheron, M. Mellein, F. Delplancke-Ströbele, M. Karl, Udo Neumann, Imke Wank, Rainer Lenzen, Odele Straub, Michael Esselborn, Armin Huber, J.-B. Le Bouquin, Ralf Klein, Juan-Luis Ramos, Erich Wiezorrek, Samuel Lévêque, K. Perraut, Frédéric Cassaing, C. E. Garcia Dabo, F. Müller, P. M. Plewa, Ewald Müller, N. Ventura, F. Chapron, Gerd Weigelt, M. Ebert, Martin Kulas, M. Wiest, Elodie Choquet, Luca Pasquini, A. Caratti o Garatti, A. Pflüger, T. de Zeeuw, Guy Perrin, Myriam Benisty, Yves Magnard, Joachim M. Bestenlehner, S. Oberti, António Amorim, Nicolas Schuhler, B. Lazareff, Paulo J. V. Garcia, Jason Dexter, Christian Straubmeier, Th. Henning, Jason Spyromilio, F. H. Vincent, A. Mérand, Senol Yazici, Felix Widmann, C. Rau, Pierre Bourget, R. J. García López, Xavier Haubois, Eric Gendron, Gérard Zins, G. Rousset, Andres J. Ramirez, Gilles Duvert, T. Paumard, Lieselotte Jochum, Idel Waisberg, F. Haussmann, O. Pfuhl, Sebastian Rabien, G. Rodríguez-Coira, Gerd Jakob, J. P. Berger, Wolfgang Brandner, D. Ziegler, and Marcos Suarez
Subjects: Physics, 010308 nuclear & particles physics, Binary number, Astronomy and Astrophysics, Astrophysics, Collision, 01 natural sciences, Galaxy, Wavelength, 13. Climate action, Space and Planetary Science, Angular diameter, 0103 physical sciences, Radiative transfer, Chromatic scale, 010303 astronomy & astrophysics, Cavity wall
Abstract: Context. η Car is one of the most intriguing luminous blue variables in the Galaxy. Observations and models of the X-ray, ultraviolet, optical, and infrared emission suggest a central binary in a highly eccentric orbit with a 5.54 yr period residing in its core. 2D and 3D radiative transfer and hydrodynamic simulations predict a primary with a dense and slow stellar wind that interacts with the faster and lower density wind of the secondary. The wind-wind collision scenario suggests that the secondary’s wind penetrates the primary’s wind creating a low-density cavity in it, with dense walls where the two winds interact. However, the morphology of the cavity and its physical properties are not yet fully constrained. Aims. We aim to trace the inner ∼5–50 au structure of η Car’s wind-wind interaction, as seen through Brγ and, for the first time, through the He I 2s-2p line. Methods. We have used spectro-interferometric observations with the K-band beam-combiner GRAVITY at the VLTI. The analyses of the data include (i) parametrical model-fitting to the interferometric observables, (ii) a CMFGEN model of the source’s spectrum, and (iii) interferometric image reconstruction. Results. Our geometrical modeling of the continuum data allows us to estimate its FWHM angular size close to 2 mas and an elongation ratio ϵ = 1.06 ± 0.05 over a PA = 130° ± 20°. Our CMFGEN modeling of the spectrum helped us to confirm that the role of the secondary should be taken into account to properly reproduce the observed Brγ and He I lines. Chromatic images across the Brγ line reveal a southeast arc-like feature, possibly associated to the hot post-shocked winds flowing along the cavity wall. The images of the He I 2s-2p line served to constrain the 20 mas (∼50 au) structure of the line-emitting region. The observed morphology of He I suggests that the secondary is responsible for the ionized material that produces the line profile. Both the Brγ and the He I 2s-2p maps are consistent with previous hydrodynamical models of the colliding wind scenario. Future dedicated simulations together with an extensive interferometric campaign are necessary to refine our constraints on the wind and stellar parameters of the binary, which finally will help us predict the evolutionary path of η Car.
Published: 2018

49. Single-mode waveguides for GRAVITY: I. The cryogenic 4-telescope integrated optics beam combiner

Author: S. Guieu, F. Patru, C. Scibetta, Sylvestre Lacour, Y. Gambérini, A. Delboulbé, Christian Straubmeier, Guy Perrin, A. Chabli, Laurent Jocou, Stefan Gillessen, Cyprien Lanthermann, E. Stadler, A. Nolot, P. Noël, S. Pocas, Thibaut Moulin, Karine Perraut, G. Chamiot-Maitral, P. Labeye, C. Vizioz, R. Templier, J.-B. Le Bouquin, Wolfgang Brandner, F. Haußmann, Frank Eisenhauer, Pierre Kervella, Oliver Pfuhl, Magdalena Lippa, V. Cardin, Yves Magnard, Marcus Haug, Noel Ventura, António Amorim, F. Joulain, J. Guerrero, S. Poulain, V. Lapras, Jean-Philippe Berger, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information (CEA-LETI), Direction de Recherche Technologique (CEA) (DRT (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Istituto Nazionale di Geofisica e di Oceanografia Sperimentale (OGS), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Département d'Optronique (DOPT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Technologique (CEA) (DRT (CEA)), Institut de biologie et chimie des protéines [Lyon] (IBCP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Le Verre Fluoré, Institute Patology and Imunology Molecular, Fac Ciencias, Universidade do Porto, Max-Planck-Institut für Astronomie (MPIA), Universität zu Köln, Universidade do Porto = University of Porto, and Universität zu Köln = University of Cologne
Subjects: Cryostat, FRONT SENSORS, Context (language use), Astrophysics, Astronomy & Astrophysics, 01 natural sciences, 7. Clean energy, Computer Science::Digital Libraries, VLTI, law.invention, 010309 optics, Telescope, Optics, law, K band, ASTRONOMICAL INTERFEROMETRY, 0103 physical sciences, 010303 astronomy & astrophysics, Physics, Very Large Telescope, Science & Technology, business.industry, high angular resolution [techniques], Astrophysics::Instrumentation and Methods for Astrophysics, techniques: high angular resolution, Astronomy and Astrophysics, H band, K-BAND, CIAO, Physics::History of Physics, interferometric [techniques], Interferometry, Space and Planetary Science, techniques: interferometric, Physical Sciences, business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Beam (structure)
Abstract: Context. Within the framework of the second-generation instrumentation of the Very Large Telescope Interferometer of the European Southern Observatory we have developed the four-telescope beam combiner in integrated optics. Aims. We optimized the performance of such beam combiners, for the first time in the near-infrared K band, for the GRAVITY instrument dedicated to the study of the close environment of the galactic centre black hole by precision narrow-angle astrometry and interferometric imaging. Methods. We optimized the design of the integrated optics chip and the manufacturing technology as well, to fulfil the very demanding throughput specification. We also designed an integrated optics assembly able to operate at 200 K in the GRAVITY cryostat to reduce thermal emission. Results. We manufactured about 50 beam combiners by silica-on-silicon etching technology. We glued the best combiners to single-mode fluoride fibre arrays that inject the VLTI light into the integrated optics beam combiners. The final integrated optics assemblies have been fully characterized in the laboratory and through on-site calibrations: their global throughput over the K band is higher than 55% and the instrumental contrast reaches more than 95% in polarized light, which is well within the GRAVITY specifications. Conclusions. While integrated optics technology is known to be mature enough to provide efficient and reliable beam combiners for astronomical interferometry in the H band, we managed to successfully extend it to the longest wavelengths of the K band and to manufacture the most complex integrated optics beam combiner in this specific spectral band.
Published: 2018

50. Nuclear Activity and the Conditions of Star-formation at the Galactic Center

Author: M. Parsa, Banafsheh Shahzamanian, M. Subroweit, Andreas Eckart, Silke Britzen, Matthew Horrobin, Ly Moser, Anton Zensus, Vladimir Karas, C. Rauch, Christian Straubmeier, M. Garcia-Marin, Michal Zajaček, D. Kunneriath, Monica Valencia-S., A. Borkar, F. Peissker, and N. Sabha
Subjects: Physics, Supermassive black hole, Star formation, Infrared, Astrophysics::High Energy Astrophysical Phenomena, Galactic Center, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Nuclear activity, Polarization (waves), Astrophysics - Astrophysics of Galaxies, Accretion (astrophysics), Astrophysics of Galaxies (astro-ph.GA), Outflow, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract: The Galactic Center is the closest galactic nucleus that can be studied with unprecedented angular resolution and sensitivity. We summarize recent basic observational results on Sagittarius A* and the conditions for star formation in the central stellar cluster. We cover results from the radio, infrared, and X-ray domain and include results from simulation as well. From (sub-)mm and near-infrared variability and near-infrared polarization data we find that the SgrA* system (supermassive black hole spin, a potential temporary accretion disk and/or outflow) is well ordered in its geometrical orientation and in its emission process that we assume to reflect the accretion process onto the supermassive black hole (SMBH)., 11 pages, 4 figures, 1 table; published in PoS-SISSA Proceedings of the: Frontier Research in Astrophysics - II, 23-28 May 2016, Mondello (Palermo), Italy
Published: 2017

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