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7 results on '"Lapeyr��re, V."'

1. The mass distribution in the Galactic Centre from interferometric astrometry of multiple stellar orbits

Author

GRAVITY Collaboration, Abuter, R., Aimar, N., Amorim, A., Ball, J., Baub��ck, M., Berger, J. P., Bonnet, H., Bourdarot, G., Brandner, W., Cardoso, V., Cl��net, Y., Dallilar, Y., Davies, R., de Zeeuw, P. T., Dexter, J., Drescher, A., Eisenhauer, F., Schreiber, N. M. F��rster, Foschi, A., Garcia, P., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Habibi, M., Haubois, X., Hei��el, G., Henning, T., Hippler, S., Horrobin, M., Jochum, L., Jocou, L., Kaufer, A., Kervella, P., Lacour, S., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Lutz, D., Ott, T., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rabien, S., Shangguan, J., Shimizu, T., Scheithauer, S., Stadler, J., Stephens, A. W., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Tristram, K. R. W., Vincent, F., von Fellenberg, S., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., and Zins, G.

Subjects
Astrophysics of Galaxies (astro-ph.GA), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics - Astrophysics of Galaxies, Astrophysics::Galaxy Astrophysics, General Relativity and Quantum Cosmology
Abstract

The stars orbiting the compact radio source Sgr A* in the Galactic Centre are precision probes of the gravitational field around the closest massive black hole. In addition to adaptive optics assisted astrometry (with NACO / VLT) and spectroscopy (with SINFONI / VLT, NIRC2 / Keck and GNIRS / Gemini) over three decades, since 2016/2017 we have obtained 30-100 mu-as astrometry with the four-telescope interferometric beam combiner GRAVITY / VLTI reaching a sensitivity of mK = 20 when combining data from one night. We present the simultaneous detection of several stars within the diffraction limit of a single telescope, illustrating the power of interferometry. The new data for the stars S2, S29, S38 and S55 yield significant accelerations between March and July 2021, as these stars pass the pericenters of their orbits between 2018 and 2023. This allows for a high-precision determination of the gravitational potential around Sgr A*. Our data are in excellent agreement with general relativity orbits around a single central point mass, M = 4.30 x 10^6 M_sun with a precision of about +-0.25%. We improve the significance of our detection of the Schwarzschild precession in the S2 orbit to 7 sigma. Assuming plausible density profiles, an extended mass component inside S2's apocentre (= 0.23" or 2.4 x 10^4 R_S) must be 3000 M_sun (1 sigma), or 0.1% of M. Adding the enclosed mass determinations from 13 stars orbiting Sgr A* at larger radii, the innermost radius at which the excess mass beyond Sgr A* tentatively is seen is r = 2.5" >= 10x the apocentre of S2. This is in full harmony with the stellar mass distribution (including stellar-mass black holes) obtained from the spatially resolved luminosity function., published in A&A

Published
2021

2. Constraining the Nature of the PDS 70 Protoplanets with VLTI/GRAVITY ∗

Author

Wang, J. J., Vigan, A., Lacour, S., Nowak, M., Stolker, T., De Rosa, R. J., Ginzburg, S., Gao, P., Abuter, R., Amorim, A., Asensio-Torres, R., Baubck, M., Benisty, M., Berger, J. P., Beust, H., Beuzit, J. -L., Blunt, S., Boccaletti, A., Bohn, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Cl��net, Y., Foresto, V. Coud�� du, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Facchini, S., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Hei��el, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houll��, M., Hubert, Z., Jim��nez-Rosales, A., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Meyer, M., Kreidberg, L., Lagrange, A. -M., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Lutz, D., Maire, A. -L., M��nard, F., M��rand, A., Molli��re, P., Monnier, J. D., Mouillet, D., M��ller, A., Nasedkin, E., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rodr��guez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Collaboration, The GRAVITY, 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
Gravity (chemistry), 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Solar and stellar astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, Orbit determination, Exoplanet formation, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Earth and planetary astrophysics, Astronomy, Astronomy and Astrophysics, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Protoplanet, Long baseline interferometry 492 487 1175 932, Astrophysics - Earth and Planetary Astrophysics, Exoplanet atmospheres
Abstract

We present K-band interferometric observations of the PDS 70 protoplanets along with their host star using VLTI/GRAVITY. We obtained K-band spectra and 100 $\mu$as precision astrometry of both PDS 70 b and c in two epochs, as well as spatially resolving the hot inner disk around the star. Rejecting unstable orbits, we found a nonzero eccentricity for PDS 70 b of $0.17 \pm 0.06$, a near-circular orbit for PDS 70 c, and an orbital configuration that is consistent with the planets migrating into a 2:1 mean motion resonance. Enforcing dynamical stability, we obtained a 95% upper limit on the mass of PDS 70 b of 10 $M_\textrm{Jup}$, while the mass of PDS 70 c was unconstrained. The GRAVITY K-band spectra rules out pure blackbody models for the photospheres of both planets. Instead, the models with the most support from the data are planetary atmospheres that are dusty, but the nature of the dust is unclear. Any circumplanetary dust around these planets is not well constrained by the planets' 1-5 $\mu$m spectral energy distributions (SEDs) and requires longer wavelength data to probe with SED analysis. However with VLTI/GRAVITY, we made the first observations of a circumplanetary environment with sub-au spatial resolution, placing an upper limit of 0.3~au on the size of a bright disk around PDS 70 b., Comment: 30 pages, 9 figures, Accepted for publication in AJ

Published
2021
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3. Direct confirmation of the radial-velocity planet $��$ Pic c

Author

Nowak, M., Lacour, S., Lagrange, A. -M., Rubini, P., Wang, J., Stolker, T., Amorim, A., Asensio-Torres, R., Baub��ck, M., Benisty, M., Berger, J. P., Beust, H., Blunt, S., Boccaletti, A., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Charnay, B., Choquet, E., Christiaens, V., Cl��net, Y., Foresto, V. Coud�� du, Cridland, A., de Zeeuw, P. T., Dembet, R., Dexter, J., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gardner, T., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Hei��el, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houll��, M., Hubert, Z., Jim��nez-Rosales, A., Jocou, L., Kammerer, J., Kervella, P., Keppler, M., Kreidberg, L., Kulikauskas, M., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., M��rand, A., Maire, A. -L., Molli��re, P., Monnier, J. D., Mouillet, D., M��ller, A., Nasedkin, E., Ott, T., Otten, G., Paumard, T., Paladini, C., Perraut, K., Perrin, G., Pueyo, L., Pfuhl, O., Rameau, J., Rodet, L., Rodr��guez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., and Collaboration, the GRAVITY

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), FOS: Physical sciences, Astrophysics::Earth and Planetary Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Astrophysics::Galaxy Astrophysics
Abstract

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. %, and thus on long orbital period. This dichotomy makes it difficult to combine the two techniques on a single target at once. 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. We observed the recently-discovered giant planet $��$ Pictoris c with GRAVITY, mounted on the Very Large Telescope Interferometer (VLTI). This study constitutes the first direct confirmation of a planet discovered through radial velocity. We find that the planet has a temperature of $T = 1250\pm50$\,K and a dynamical mass of $M = 8.2\pm0.8\,M_{\rm Jup}$. At $18.5\pm2.5$\,Myr, this puts $��$ Pic 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 ($M_{\rm K} = 14.3 \pm 0.1$) favours a core accretion scenario. 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., 10 pages

Published
2020
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4. Deep images of the Galactic center with GRAVITY

Author

GRAVITY Collaboration, Abuter, R., Aimar, N., Amorim, A., Arras, P., Baub��ck, M., Berger, J. P., Bonnet, H., Brandner, W., Bourdarot, G., Cardoso, V., Cl��net, Y., Davies, R., de Zeeuw, P. T., Dexter, J., Dallilar, Y., Drescher, A., Eisenhauer, F., En��lin, T., Schreiber, N. M. F��rster, Garcia, P., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Habibi, M., Haubois, X., Hei��el, G., Henning, T., Hippler, S., Horrobin, M., Jim��nez-Rosales, A., Jochum, L., Jocou, L., Kaufer, A., Kervella, P., Lacour, S., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Lutz, D., Mang, F., Nowak, M., Ott, T., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rabien, S., Shangguan, J., Shimizu, T., Scheithauer, S., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Tristram, K. R. W., Vincent, F., von Fellenberg, S., Waisberg, I., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., and Zins, G.

Subjects
Astrophysics and Astronomy, Techniques - high angular resolution, Methods: numerical, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics - astrophysics of galaxies, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, Methods - statistical, Astrophysics::Cosmology and Extragalactic Astrophysics, Black hole physics, Galaxy - nucleus, Techniques - image processing, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Galaxy Astrophysics
Abstract

Stellar orbits at the Galactic Center provide a very clean probe of the gravitational potential of the supermassive black hole. They can be studied with unique precision, beyond the confusion limit of a single telescope, with the near-infrared interferometer GRAVITY. Imaging is essential to search the field for faint, unknown stars on short orbits which potentially could constrain the black hole spin. Furthermore, it provides the starting point for astrometric fitting to derive highly accurate stellar positions. Here, we present $\mathrm{G^R}$, a new imaging tool specifically designed for Galactic Center observations with GRAVITY. The algorithm is based on a Bayesian interpretation of the imaging problem, formulated in the framework of information field theory and building upon existing works in radio-interferometric imaging. Its application to GRAVITY observations from 2021 yields the deepest images to date of the Galactic Center on scales of a few milliarcseconds. The images reveal the complicated source structure within the central $100\,\mathrm{mas}$ around Sgr A*, where we detected the stars S29 and S55 and confirm S62 on its trajectory, slowly approaching Sgr A*. Furthermore, we were able to detect S38, S42, S60, and S63 in a series of exposures for which we offset the fiber from Sgr A*. We provide an update on the orbits of all aforementioned stars. In addition to these known sources, the images also reveal a faint star moving to the west at a high angular velocity. We cannot find any coincidence with any known source and, thus, we refer to the new star as S300. From the flux ratio with S29, we estimate its K-band magnitude as $m_\mathrm{K}\left(\mathrm{S300}\right)\simeq 19.0 - 19.3$. Images obtained with CLEAN confirm the detection., 24 pages, 14 figures

Published
2022
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5. GRAVITY K-band spectroscopy of HD 206893 B

Author

Kammerer, J., Lacour, S., Stolker, T., Molli��re, P., Sing, D. K., Nasedkin, E., Kervella, P., Wang, J. J., Ward-Duong, K., Nowak, M., Abuter, R., Amorim, A., Asensio-Torres, R., Baub��ck, M., Benisty, M., Berger, J. -P., Beust, H., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M. -L., Bonnefoy, M., Bonnet, H., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Cl��net, Y., Foresto, V. Coud�� du, Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Lopez, R. Garcia, Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Hei��el, G., Henning, T., Hinkley, S., Hippler, S., Horrobin, M., Houll��, M., Hubert, Z., Jocou, L., Keppler, M., Kreidberg, L., Lagrange, A. -M., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Lutz, D., Maire, A. -L., M��rand, A., Monnier, J. D., Mouillet, D., M��ller, A., Ott, T., Otten, G. P. P. L., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Pueyo, L., Rameau, J., Rodet, L., Rousset, G., Rustamkulov, Z., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., van Dishoeck, E. F., Vigan, A., Vincent, F., von Fellenberg, S. D., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., and Collaboration, GRAVITY

Subjects
Interferometric, Proper motion, Extinction (astronomy), Brown dwarf, FOS: Physical sciences, Orbital eccentricity, Astrophysics, Astrophysic, Astrophysics::Solar and Stellar Astrophysics, Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Gaseous Planets, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Orbital elements, Debris disk, Planets and Satellites: Atmospheres, Astronomy and Astrophysics, Techniques, Exoplanet, Radial velocity, Detection, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Earth and Planetary Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We aim to reveal the nature of the reddest known substellar companion HD 206893 B by studying its near-infrared colors and spectral morphology and by investigating its orbital motion. We fit atmospheric models for giant planets and brown dwarfs and perform spectral retrievals with petitRADTRANS and ATMO on the observed GRAVITY, SPHERE, and GPI spectra of HD 206893 B. To recover its unusual spectral features, we include additional extinction by high-altitude dust clouds made of enstatite grains in the atmospheric model fits. We also infer the orbital parameters of HD 206893 B by combining the $\sim 100~��\text{as}$ precision astrometry from GRAVITY with data from the literature and constrain the mass and position of HD 206893 C based on the Gaia proper motion anomaly of the system. The extremely red color and the very shallow $1.4~��\text{m}$ water absorption feature of HD 206893 B can be fit well with the adapted atmospheric models and spectral retrievals. Altogether, our analysis suggests an age of $\sim 3$-$300~\text{Myr}$ and a mass of $\sim 5$-$30~\text{M}_\text{Jup}$ for HD 206893 B, which is consistent with previous estimates but extends the parameter space to younger and lower-mass objects. The GRAVITY astrometry points to an eccentric orbit ($e = 0.29^{+0.06}_{-0.11}$) with a mutual inclination of $< 34.4~\text{deg}$ with respect to the debris disk of the system. While HD 206893 B could in principle be a planetary-mass companion, this possibility hinges on the unknown influence of the inner companion on the mass estimate of $10^{+5}_{-4}~\text{M}_\text{Jup}$ from radial velocity and Gaia as well as a relatively small but significant Argus moving group membership probability of $\sim 61\%$. However, we find that if the mass of HD 206893 B is $< 30~\text{M}_\text{Jup}$, then the inner companion HD 206893 C should have a mass between $\sim 8$-$15~\text{M}_\text{Jup}$., 28 pages, 19 figures, accepted for publication in A&A

Published
2021
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6. The GRAVITY young stellar object survey

Author

GRAVITY Collaboration, Eupen, F., Labadie, L., Grellmann, R., Perraut, K., Brandner, W., Duch��ne, G., K��hler, R., Sanchez-Bermudez, J., Lopez, R. Garcia, Garatti, A. Caratti o, Benisty, M., Dougados, C., Garcia, P., Klarmann, L., Amorim, A., Baub��ck, M., Berger, J. P., Caselli, P., Cl��net, Y., Foresto, V. Coud�� du, de Zeeuw, P. T., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Filho, M., Ganci, V., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Heissel, G., Henning, Th., Hippler, S., Horrobin, M., Hubert, Z., Jim��nez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyr��re, V., Bouquin, J. B. Le, L��na, P., Ott, T., Paumard, T., Perrin, G., Pfuhl, O., Rodr��guez-Coira, G., Rousset, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., van Dishoeck, E., Vincent, F., von Fellenberg, S. D., Widmann, F., Woillez, J., and Wojtczak, A.

Subjects
Techniques: Interferometric, Young stellar object, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, 01 natural sciences, 010309 optics, Stars: Pre-Main Sequence, 0103 physical sciences, Binary star, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Techniques: High Angular Resolution, Orbital elements, Physics, Infrared excess, Herbig Ae/Be, Astronomy and Astrophysics, Mass ratio, Accretion (astrophysics), Binaries: Close, T Tauri star, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Stars: Variables: T Tauri, Astrophysics::Earth and Planetary Astrophysics, Circumbinary planet, Stars: Individual: WW Cha
Abstract

The young T Tauri star WW Cha was recently proposed to be a close binary object with strong infrared and submillimeter excess associated with circum-system emission. This makes WW Cha a very interesting source for studying the influence of dynamical effects on circumstellar as well as circumbinary material. We derive the relative astrometric positions and flux ratios of the stellar companion in WW Cha from the interferometric model fitting of observations made with the VLTI instruments AMBER, PIONIER, and GRAVITY in the near-infrared from 2011 to 2020. For two epochs, the resulting uv-coverage in spatial frequencies permits us to perform the first image reconstruction of the system in the K band. The positions of nine epochs are used to determine the orbital elements and the total mass of the system. We find the secondary star orbiting the primary with a period of T=206.55 days, a semimajor axis of a=1.01 au, and a relatively high eccentricity of e=0.45. Combining the orbital solution with distance measurements from Gaia DR2 and the analysis of evolutionary tracks, the dynamical mass of Mtot=3.20 Msol can be explained by a mass ratio between ~0.5 and 1. The orbital angular momentum vector is in close alignment with the angular momentum vector of the outer disk as measured by ALMA and SPHERE. The analysis of the relative photometry suggests the presence of infrared excess surviving in the system and likely originating from truncated circumstellar disks. The flux ratio between the two components appears variable, in particular in the K band, and may hint at periods of triggered higher and lower accretion or changes in the disks' structures. The knowledge of the orbital parameters, combined with a relatively short period, makes WW Cha an ideal target for studying the interaction of a close young T Tauri binary with its surrounding material, such as time-dependent accretion phenomena., Comment: Accepted for publication in A&A; 24 pages, 14 figures, 3 tables; affiliations corrected

Published
2021
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7. Modeling the orbital motion of Sgr A*’s near-infrared flares

Author

The GRAVITY Collaboration, Baub��ck, M., Dexter, J., Abuter, R., Amorim, A., Berger, J. P., Bonnet, H., Brandner, W., Cl��net, Y., Foresto, V. Coud�� du, de Zeeuw, P. T., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. F��rster, Gao, F., Garcia, P., Gendron, E., Genzel, R., Gerhard, O., Gillessen, S., Habibi, M., Haubois, X., Henning, T., Hippler, S., Horrobin, M., Jim��nez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Ott, T., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rabien, S., Coira, G. Rodriguez, Rousset, G., Scheithauer, S., Stadler, J., Sternberg, A., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Vincent, F., von Fellenberg, S., Waisberg, I., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., 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, 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), 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), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and 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)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Infrared, Event horizon, Astrophysics::High Energy Astrophysical Phenomena, black hole physics, FOS: Physical sciences, Astrophysics, 01 natural sciences, law.invention, Gravitation, General Relativity and Quantum Cosmology, accretion, law, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 14. Life underwater, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Galaxy: center, 010308 nuclear & particles physics, accretion disks, Galactic Center, Astronomy and Astrophysics, Light curve, Accretion (astrophysics), [SDU]Sciences of the Universe [physics], Space and Planetary Science, Orbital motion, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Flare
Abstract

Infrared observations of Sgr A* probe the region close to the event horizon of the black hole at the Galactic center. These observations can constrain the properties of low-luminosity accretion as well as that of the black hole itself. The GRAVITY instrument at the ESO VLTI has recently detected continuous circular relativistic motion during infrared flares which has been interpreted as orbital motion near the event horizon. Here we analyze the astrometric data from these flares, taking into account the effects of out-of-plane motion and orbital shear of material near the event horizon of the black hole. We have developed a new code to predict astrometric motion and flux variability from compact emission regions following particle orbits. Our code combines semi-analytic calculations of timelike geodesics that allow for out-of-plane or elliptical motions with ray tracing of photon trajectories to compute time-dependent images and light curves. We apply our code to the three flares observed with GRAVITY in 2018. We show that all flares are consistent with a hotspot orbiting at R$\sim$9 gravitational radii with an inclination of $i\sim140^\circ$. The emitting region must be compact and less than $\sim5$ gravitational radii in diameter. We place a further limit on the out-of-plane motion during the flare., Comment: Accepted in A&A

Published
2020
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