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1. Glitch systematics on the observation of massive black-hole binaries with LISA

Author: Spadaro, A, Buscicchio, R, Vetrugno, D, Klein, A, Gerosa, D, Vitale, S, Dolesi, R, Joseph Weber, W, Colpi, M, Alice Spadaro, Riccardo Buscicchio, Daniele Vetrugno, Antoine Klein, Davide Gerosa, Stefano Vitale, Rita Dolesi, William Joseph Weber, Monica Colpi, Spadaro, A, Buscicchio, R, Vetrugno, D, Klein, A, Gerosa, D, Vitale, S, Dolesi, R, Joseph Weber, W, Colpi, M, Alice Spadaro, Riccardo Buscicchio, Daniele Vetrugno, Antoine Klein, Davide Gerosa, Stefano Vitale, Rita Dolesi, William Joseph Weber, and Monica Colpi
Abstract: Detecting and coherently characterizing thousands of gravitational-wave signals is a core data-analysis challenge for the Laser Interferometer Space Antenna (LISA). Transient artifacts, or "glitches", with disparate morphologies are expected to be present in the data, potentially affecting the scientific return of the mission. We present the first joint reconstruction of short-lived astrophysical signals and noise artifacts. Our analysis is inspired by glitches observed by the LISA Pathfinder mission, including both acceleration and fast displacement transients. We perform full Bayesian inference using LISA time-delay interferometric data and gravitational waveforms describing mergers of massive black holes. We focus on a representative binary with a detector-frame total mass of 6×107M⊙ at redshift 5, yielding a signal lasting ∼30 h in the LISA sensitivity band. We explore two glitch models of different flexibility, namely a fixed parametric family and a shapelet decomposition. In the most challenging scenario, we report a complete loss of the gravitational-wave signals if the glitch is ignored; more modest glitches induce biases on the black-hole parameters. On the other hand, a joint inference approach fully sanitizes the reconstruction of both the astrophysical and the glitch signal. We also inject a variety of glitch morphologies in isolation, without a superimposed gravitational signal, and show we can identify the correct transient model. Our analysis is an important stepping stone toward a realistic treatment of LISA data in the context of the highly sought-after "global fit".
Published: 2023

2. In-flight testing of the injection of the LISA Pathfinder test mass into a geodesic

Author: D. Vignotto, Oliver Jennrich, Jacob Slutsky, Valerio Ferroni, A. Zambotti, D. Hoyland, Pierre Binétruy, Michele Armano, I. Harrison, A. Cesarini, G. Russano, M. Freschi, Gerhard Heinzel, N. Meshksar, Christian J. Killow, Luigi Ferraioli, Antonella Cavalleri, R. Giusteri, Peter Zweifel, Tamara Sumner, J. Grzymisch, Daniele Bortoluzzi, L. Mendes, Catia Grimani, H. Ward, S. Vitale, L. Liu, E. Castelli, J. Martino, Miquel Nofrarías, B. Kaune, Daniele Vetrugno, M. de Deus Silva, A. Wittchen, Mauro Hueller, L. Wissel, L. Martin-Polo, J. A. Lobo, S. Paczkowski, Nikolaos Karnesis, Michael Perreur-Lloyd, D. I. Robertson, G. Dixon, M.-S. Hartig, N. Korsakova, Domenico Giardini, Heather Audley, C. Zanoni, Davor Mance, Martin Hewitson, José F. F. Mendes, D. Texier, Ph. Jetzer, F. Rivas, J. P. López-Zaragoza, Ferran Gibert, P. Pivato, J. Baird, Karsten Danzmann, Antoine Petiteau, Paul McNamara, Eric Plagnol, V. Martín, Carlos F. Sopuerta, Gudrun Wanner, Juan Ramos-Castro, W. J. Weber, H. Inchauspe, Ingo Diepholz, E. D. Fitzsimons, Peter Wass, Rita Dolesi, A. M. Cruise, J. Reiche, Lluis Gesa, R. Maarschalkerweerd, F. Martin-Porqueras, Daniel Hollington, M. Born, James Ira Thorpe, Université Paris Diderot, Sorbonne Université, German Centre for Air and Space Travel, Federal Ministry for Economics Affairs and Energy (Germany), Istituto Nazionale di Fisica Nucleare, Ministerio de Economía y Competitividad (España), Consejo Superior de Investigaciones Científicas (España), UK Space Agency, University of Glasgow, Swiss National Science Foundation, University of Birmingham, National Aeronautics and Space Administration (US), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-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 Cité (UPCité)
Subjects: velocity, Atmospheric Science, experimental methods, detector: satellite, 010504 meteorology & atmospheric sciences, Computer science, Mission critical, Aerospace Engineering, Residual, 01 natural sciences, 7. Clean energy, LISA Pathfinder, Acceleration, Impulse measurement, Space mechanism in-flight testing, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], force: electrostatic, noise: acceleration, Aerospace engineering, capture, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Injection into geodesic motion, LISA, mass: injection, Payload, business.industry, Gravitational wave, gravitational radiation, Astronomy and Astrophysics, gravitational radiation detector, Telecommand, experimental equipment, Geophysics, Pathfinder, gravitation, Space and Planetary Science, trajectory, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Trajectory, General Earth and Planetary Sciences, business, geodesic, experimental results, LISA pathfinder
Abstract: LISA Pathfinder is a technology demonstrator space mission, aimed at testing key technologies for detecting gravitational waves in space. The mission is the precursor of LISA, the first space gravitational waves observatory, whose launch is scheduled for 2034. The LISA Pathfinder scientific payload includes two gravitational reference sensors (GRSs), each one containing a test mass (TM), which is the sensing body of the experiment. A mission critical task is to set each TM into a pure geodesic motion, i.e. guaranteeing an extremely low acceleration noise in the sub-Hertz frequency bandwidth. The grabbing positioning and release mechanism (GPRM), responsible for the injection of the TM into a geodesic trajectory, was widely tested on ground, with the limitations imposed by the 1-g environment. The experiments showed that the mechanism, working in its nominal conditions, is capable of releasing the TM into free-fall fulfilling the very strict constraint imposed on the TM residual velocity, in order to allow its capture on behalf of the electrostatic actuation. However, the first in-flight releases produced unexpected residual velocity components, for both the TMs. Moreover, all the residual velocity components were greater than maximum value set by the requirements. The main suspect is that unexpected contacts took place between the TM and the surroundings bodies. As a consequence, ad hoc manual release procedures had to be adopted for the few following injections performed during the nominal mission. These procedures still resulted in non compliant TM states which were captured only after impacts. However, such procedures seem not practicable for LISA, both for the limited repeatability of the system and for the unmanageable time lag of the telemetry/telecommand signals (about 4400 s). For this reason, at the end of the mission, the GPRM was deeply tested in-flight, performing a large number of releases, according to different strategies. The tests were carried out in order to understand the unexpected dynamics and limit its effects on the final injection. Some risk mitigation maneuvers have been tested aimed at minimizing the vibration of the system at the release and improving the alignment between the mechanism and the TM. However, no overall optimal release strategy to be implemented in LISA could be found, because the two GPRMs behaved differently., This work has been made possible by the LISA Pathfinder mission, which is part of the space-science programme of the European Space Agency.The French contribution has been supported by the CNES (Accord Specific de projet CNES 1316634/CNRS 103747), the CNRS, the Observatoire de Paris and the University Paris-Diderot.E. Plagnol and H. Inchauspé would also like to acknowledge the financial support of the UnivEarthS Labex program at Sorbonne Paris Cité (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02).The Albert-Einstein-Institut acknowledges the support of the German Space Agency, DLR. The work is supported by the Federal Ministry for Economic Affairs and Energy based on a resolution of the German Bundestag (FKZ 50OQ0501 and FKZ 50OQ1601).The Italian contribution has been supported by Agenzia Spaziale Italiana and Istituto Nazionale di Fisica Nucleare.The Spanish contribution has been supported by contracts AYA2010-15709 (MICINN), ESP2013-47637-P, and ESP2015-67234-P (MINECO).M. Nofrarias acknowledges support from Fundacion General CSIC (Programa ComFuturo).F. Rivas acknowledges an FPI contract (MINECO). The Swiss contribution acknowledges the support of the Swiss Space Office (SSO) via the PRODEX Programme of ESA. L. Ferraioli is supported by the Swiss National Science Foundation.The UK groups wish to acknowledge support from the United Kingdom Space Agency (UKSA), the University of Glasgow, the University of Birmingham,Imperial College, and the Scottish Universities Physics Alliance (SUPA). J. I. Thorpe and J. Slutsky acknowledge the support of the US National Aeronautics and Space Administration (NASA).
Published: 2021

3. Detecting gravitomagnetism with space-based gravitational wave observatories

Author: Giuseppe Pucacco, Valerio Ferroni, Massimo Bassan, Angelo Tartaglia, and Daniele Vetrugno
Subjects: Settore FIS/01, space-detectors, LISA, Physics and Astronomy (miscellaneous), galaxy, gravito-magnetism, dark matter
Abstract: We discuss the idea of a measurement that, making use of data from space interferometers, could detect the gravito-magnetic field generated by the rotation of the Milky Way, including the possible contribution of the dark matter halo. The galactic signal would be superposed to the gravito-magnetic field of the Sun. The proposed technique is based on the asymmetric propagation of light along the closed contour of the space interferometer, in a Sagnac-like approach. We discuss the principles of detection as well as some practical aspects of the proposed experiment using, as a case study, LISA, the most mature project to date. Both gravito-magnetic signals will be modulated thanks to the annual oscillation of the plane of the interferometer with respect to the galactic plane and to the spin axis of the Sun. Although larger than the detector intrinsic noise, these signals will be superposed to a much larger kinematic modulation due to orbital motion, making them very hard to be observed. We also mention a second phenomenon, where the gravito-magnetic field rotates the polarization of the propagating electromagnetic beams: the effect will be present in LISA, although exceedingly small and out of reach of present technology.
Published: 2022

4. Time Delay Interferometry combinations as instrument noise monitors for LISA

Author: Daniele Vetrugno, Olaf Hartwig, Stefano Vitale, and Martina Muratore
Subjects: Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), General Relativity and Quantum Cosmology
Abstract: The LISA mission will likely be a signal dominated detector, such that one challenge is the separation of the different astrophysical sources, and to distinguish between them and the instrumental noise. One of the goals of LISA is to probe the early Universe by detecting stochastic GW backgrounds. As correlation with other detectors is not possible for LISA, discrimination of such a GW background from the instrumental noise requires a good estimate of the latter. To this purpose we have revisited Time Delay Interferometry (TDI) to look for new TDI signal combinations that fulfill the laser frequency noise suppression requirements. We illustrate that it is possible to do a linear combination of these TDI channels to find special null-combinations that suppress gravitational waves and mainly carry information about instrumental noise. We find that there exist many null-combinations that show different sensitivities to gravitational waves, some of which seem more suitable than the traditional T combination for estimating test-mass acceleration noise. In an idealised LISA configuration, they are all sensitive to a particular linear combination of the six test-masses acceleration, similar to a rigid rotation of the LISA triangle. In the following article, we illustrate what are the noise properties that can be extracted by monitoring these interferometry signals and discuss the implication of these findings for the detection of stochastic GW backgrounds.
Published: 2021
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5. Analysis of the accuracy of actuation electronics in the laser interferometer space antenna pathfinder

Author: N. Korsakova, Heather Audley, Gerhard Heinzel, Lluis Gesa, R. Maarschalkerweerd, Daniele Vetrugno, N. Cardines, S. Vitale, J. ten Pierick, Michele Armano, F. Martin-Porqueras, S. Paczkowski, B. Kaune, E. Castelli, José F. F. Mendes, M. Freschi, M. Hueller, N. Meshksar, J. Reiche, Luigi Ferraioli, P. Pivato, Rita Dolesi, Tamara Sumner, Nikolaos Karnesis, Peter Wass, A. M. Cruise, Ph. Jetzer, M. de Deus Silva, Antonella Cavalleri, J. Baird, E. D. Fitzsimons, Antoine Petiteau, Henri Inchauspe, J. P. López-Zaragoza, M.-S. Hartig, Paul McNamara, Ferran Gibert, Michael Perreur-Lloyd, I. Mateos, Oliver Jennrich, J. Martino, Carlos F. Sopuerta, Martin Hewitson, Karsten Danzmann, Daniel Hollington, W. J. Weber, Catia Grimani, L. Wissel, J. Grzymisch, H. Ward, Daniele Bortoluzzi, L. Mendes, F. Rivas, Miquel Nofrarías, Gudrun Wanner, Juan Ramos-Castro, Eric Plagnol, V. Martín, Domenico Giardini, A. Wittchen, R. Giusteri, M. Born, James Ira Thorpe, Christian J. Killow, D. I. Robertson, A. Cesarini, G. Russano, G. Dixon, Peter Zweifel, Davor Mance, D. Texier, Jacob Slutsky, Valerio Ferroni, D. Hoyland, L. Martin-Polo, I. Harrison, Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, European Space Agency, Centre National de la Recherche Scientifique (France), Université Paris Diderot, Sorbonne Université, Agenzia Spaziale Italiana, Istituto Nazionale di Fisica Nucleare, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, Agencia Estatal de Investigación (España), Fundación General CSIC, Swiss National Science Foundation, Swiss Space Office, UK Space Agency, National Aeronautics and Space Administration (US), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-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 Cité (UPCité)
Subjects: Signal processing, Acoustics, Electrical properties and parameters, Analog-to-digital converter, Residual, 01 natural sciences, 010305 fluids & plasmas, law.invention, Electromagnetic radiation detectors, Computer Science::Robotics, Acceleration, law, Electrostatics, 0103 physical sciences, Waveform, Control equipment, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation, 010302 applied physics, Physics, Enginyeria de la telecomunicació::Radiocomunicació i exploració electromagnètica::Antenes i agrupacions d'antenes [Àrees temàtiques de la UPC], Spacecraft, business.industry, Field programmable gate array, Spacecrafts, Tractament del senyal, Enginyeria de la telecomunicació::Processament del senyal [Àrees temàtiques de la UPC], Control system, Gravitational force, Antennas (Electronics), Antenes (Electrònica), business, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Voltage
Abstract: M. Armano et al., The Laser Interferometer Space Antenna Pathfinder (LPF) main observable, labeled Δg, is the differential force per unit mass acting on the two test masses under free fall conditions after the contribution of all non-gravitational forces has been compensated. At low frequencies, the differential force is compensated by an applied electrostatic actuation force, which then must be subtracted from the measured acceleration to obtain Δg. Any inaccuracy in the actuation force contaminates the residual acceleration. This study investigates the accuracy of the electrostatic actuation system and its impact on the LPF main observable. It is shown that the inaccuracy is mainly caused by the rounding errors in the waveform processing and also by the random error caused by the analog to digital converter random noise in the control loop. Both errors are one order of magnitude smaller than the resolution of the commanded voltages. We developed a simulator based on the LPF design to compute the close-to-reality actuation voltages and, consequently, the resulting actuation forces. The simulator is applied during post-processing the LPF data., This work was supported by ETH Research Grant No. ETH-05 16-2, and it has been made possible by the LISA Pathfinder mission, which is part of the space-science program of the European Space Agency. The French contribution has been supported by the CNES (Accord Specific de Projet Grant No. CNES 1316634/CNRS 103747), the CNRS, the Observatoire de Paris, and University Paris-Diderot. E. Plagnol and H. Inchauspé would also like to acknowledge the financial support of the UnivEarthS Labex program at Sorbonne Paris Cité (Grant Nos. ANR-10-LABX-0023 and ANR-11-IDEX-0005-02). The Albert-Einstein-Institut acknowledges the support of the German Space Agency, DLR. The work is supported by the Federal Ministry for Economic Affairs and Energy based on a resolution of the German Bundestag (Grant Nos. FKZ 50OQ0501 and FKZ 50OQ1601). The Italian contribution has been supported by the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare. The Spanish contribution has been supported by Contract Nos. AYA2010-15709 (MICINN), ESP2013-47637-P, ESP2015-67234-P, and ESP2017-90084-P (MINECO). Support from AGAUR (Generalitat de Catalunya) contract 2017-SGR-1469 is also acknowledged. M. Nofrarias acknowledges support from Fundacion General CSIC (Programa ComFuturo). F. Rivas acknowledges an FPI contract from MINECO. The Swiss contribution acknowledges the support of the Swiss Space Office (SSO) via the PRODEX Programme of the ESA. L. Ferraioli is supported by the Swiss National Science Foundation. The UK groups wish to acknowledge support from the United Kingdom Space Agency (UKSA), the University of Glasgow, the University of Birmingham, Imperial College, and the Scottish Universities Physics Alliance (SUPA). J. I. Thorpe and J. Slutsky acknowledge the support of the U.S. National Aeronautics and Space Administration (NASA). N. Korsakova would like to thank the support from the CNES Fellowship. The LISA Pathfinder collaboration would like to acknowledge Professor Pierre Binetruy (deceased 30 March 2017) and Professor José Alberto Lobo (deceased 30 September 2012) for their contribution to the LISA Pathfinder science.
Published: 2020

6. Revisitation of time delay interferometry combinations that suppress laser noise in LISA

Author: Daniele Vetrugno, Martina Muratore, and Stefano Vitale
Subjects: Physics, Mathematical logic, Laser noise, Physics and Astronomy (miscellaneous), 010308 nuclear & particles physics, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Laser, 01 natural sciences, Shapiro delay, General Relativity and Quantum Cosmology, law.invention, Acceleration, Interferometry, Noise, law, 0103 physical sciences, 010306 general physics, Astrophysics - Instrumentation and Methods for Astrophysics, Algorithm, Instrumentation and Methods for Astrophysics (astro-ph.IM), Active noise control
Abstract: With the purpose of understanding how time delay interferometry (TDI) combinations can best be used for the characterisation of LISA instrumental noise, we revisit their laser frequency noise cancellation properties. We have developed an algorithm to search for all possible combinations that suppress noise at the same level as the X, Y and Z classical combination. The algorithm calculates delays using symbolic formulas that explicitly include velocities and accelerations of satellites up to the relevant order. In addition, once a combination has been identified, delays are verified by solving numerically the relevant equations using Keplerian orbits and Shapiro delay corrections. We find that the number of combinations that suppress the noise is larger than what was reported in the literature. In particular we find that some combinations that were thought to only partly suppress the noise, in reality do suppress it at the same level of accuracy as the basic X, Y and Z combinations.
Published: 2020

7. Spacecraft and interplanetary contributions to the magnetic environment on-board LISA Pathfinder

Author: Daniele Vetrugno, L. Martin-Polo, Pierre Binétruy, J. Martino, C. Trenkel, P. Pivato, L. Liu, E. Castelli, F. Martin-Porqueras, Lluis Gesa, L. Wissel, D. Giardini, Gerhard Heinzel, R. Giusteri, A. Cesarini, G. Russano, R. Maarschalkerweerd, Ignacio Mateos, F. Rivas, N. Korsakova, Nikolaos Karnesis, L. Ferraioli, M. Born, D. Mance, J. Baird, James Ira Thorpe, Antoine Petiteau, Rita Dolesi, B. Kaune, Gudrun Wanner, W. J. Weber, Paul McNamara, Eric Plagnol, V. Martín, Michael Perreur-Lloyd, Jacob Slutsky, Valerio Ferroni, Juan Ramos-Castro, D. Texier, Christian J. Killow, Carlos F. Sopuerta, D. Hoyland, Michele Armano, Martin Hewitson, D. I. Robertson, J. Grzymisch, Daniele Telloni, Mauro Hueller, Daniel Hollington, Ph. Jetzer, H. Ward, Heather Audley, José F. F. Mendes, Daniele Bortoluzzi, A. M. Cruise, G. Dixon, E.D. Fitzsimons, Antonella Cavalleri, J. Reiche, M. Freschi, M.-S. Hartig, H. Inchauspe, P. Zweifel, L. Mendes, Karsten Danzmann, D. Wealthy, Ingo Diepholz, Miquel Nofrarías, Peter Wass, D. Roma-Dollase, J. A. Lobo, S. Paczkowski, Catia Grimani, M. de Deus Silva, Oliver Jennrich, A. Wittchen, Tamara Sumner, J. P. López-Zaragoza, Ferran Gibert, I. Harrison, S. Vitale, N. Meshksar, Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Science and Technology Facilities Council (STFC), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Gravitational-wave observatory, magnetic moment, magnetic fields, 01 natural sciences, Interplanetary magnetic field, space vehicles: instruments, Física::Relativitat::Gravitació [Àrees temàtiques de la UPC], 010303 astronomy & astrophysics, magnetic field: fluctuation, susceptibility: magnetic, Physics, Magnetic moment, Astrophysics::Instrumentation and Methods for Astrophysics, solar, Magnetic field, observatory, Solar wind, gravitational waves, SOLAR-WIND, Physical Sciences, Physics::Space Physics, Astrophysics - Instrumentation and Methods for Astrophysics, geodesic, noise, FOS: Physical sciences, Astronomy & Astrophysics, gravitational waves -magnetic fields -space vehicles: instruments, Gravitational waves, Ones gravitacionals, 0103 physical sciences, 0201 Astronomical and Space Sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), LISA, Science & Technology, Spacecraft, business.industry, gravitational radiation, Astronomy and Astrophysics, Space vehicles, stability, sensitivity, Magnetic susceptibility, Computational physics, Space and Planetary Science, Magnetic fields, Interplanetary spaceflight, business, Instruments
Abstract: LISA Pathfinder (LPF) has been a space-based mission designed to test new technologies that will be required for a gravitational wave observatory in space. Magnetically driven forces play a key role in the instrument sensitivity in the low-frequency regime (mHz and below), the measurement band of interest for a space-based observatory. The magnetic field can couple to the magnetic susceptibility and remanent magnetic moment from the test masses and disturb them from their geodesic movement. LISA Pathfinder carried on-board a dedicated magnetic measurement subsystem with noise levels of 10 $ \rm nT \ Hz^{-1/2}$ from 1 Hz down to 1 mHz. In this paper we report on the magnetic measurements throughout LISA Pathfinder operations. We characterise the magnetic environment within the spacecraft, study the time evolution of the magnetic field and its stability down to 20 $\mu$Hz, where we measure values around 200 $ \rm nT \ Hz^{-1/2}$ and identify two different frequency regimes, one related to the interplanetary magnetic field and the other to the magnetic field originating inside the spacecraft. Finally, we characterise the non-stationary component of the fluctuations of the magnetic field below the mHz and relate them to the dynamics of the solar wind., Comment: 16 pages, 17 figures. MNRAS LaTeX style file version 3.0
Published: 2020

8. Actuation crosstalk in free-falling systems: Torsion pendulum results for the engineering model of the LISA pathfinder gravitational reference sensor

Author: Antonella Cavalleri, Aniello Grado, N. Finetti, Mauro Hueller, Massimo Bassan, L. Di Fiore, F. Garufi, Massimo Visco, Leopoldo Milano, R. De Rosa, Y. Minenkov, Ruggero Stanga, W. J. Weber, F. De Marchi, Rita Dolesi, M. De Laurentis, L. Marconi, Daniele Vetrugno, Giuseppe Pucacco, S. Vitale, Bassan, M., Cavalleri, A., De Laurentis, M., De Marchi, F., De Rosa, Rosario., Di Fiore, L., Dolesi, R., Finetti, N., Garufi, F., Grado, A., Hueller, M., Marconi, L., Milano, L., Minenkov, Y., Pucacco, G., Stanga, R., Vetrugno, D., Visco, M., Vitale, S., and Weber, W. J.
Subjects: Physics, LISA, 010308 nuclear & particles physics, Acoustics, Settore FIS/01 - Fisica Sperimentale, Actuation, Astrophysics::Instrumentation and Methods for Astrophysics, Torsion pendulum, Astronomy and Astrophysics, Control force, 01 natural sciences, Gravitation, Crosstalk, Free falling, Pathfinder, Classical mechanics, Torsion pendulum clock, 0103 physical sciences, Inertial motion, Reference sensor, Torque, 010306 general physics, Inertial motion, Crosstalk, Torsion pendulum, LISA, Actuation
Abstract: In this paper we report on measurements on actuation crosstalk, relevant to the gravitational reference sensors for LISA Pathfinder and LISA. In these sensors, a Test Mass (TM) falls freely within a system of electrodes used for readout and control. These measurements were carried out on ground with a double torsion pendulum that allowed us to estimate both the torque injected into the sensor when a control force is applied and, conversely, the force leaking into the translational degree of freedom due to the applied torque.The values measured on our apparatus (the engineering model of the LISA Pathfinder sensor) agree to within 0.2% (over a maximum measured crosstalk of 1%) with predictions of a mathematical model when measuring force to torque crosstalk, while it is somewhat larger than expected (up to 3.5%) when measuring torque to force crosstalk. However, the values in the relevant range, i.e. when the TM is well centered ( ± 10 µm) in the sensor, remain smaller than 0.2%, satisfying the LISA Pathfinder requirements.
Published: 2018

9. LISA Pathfinder platform stability and drag-free performance

Author: N. Korsakova, Gerhard Heinzel, Michele Armano, Ian Harrison, M. Freschi, Henri Inchauspe, R. Giusteri, Ph. Jetzer, M. de Deus Silva, Domenico Giardini, J. P. López-Zaragoza, Rita Dolesi, J. Baird, J. Grzymisch, H. Ward, W. J. Weber, Ferran Gibert, F. Martin-Porqueras, Daniele Vetrugno, E. D. Fitzsimons, F. Rivas, Peter Wass, S. Paczkowski, Jacob Slutsky, L. Martin-Polo, Valerio Ferroni, Luigi Ferraioli, D. Hoyland, L. Wissel, P. Zweifel, James Ira Thorpe, Oliver Jennrich, Antonella Cavalleri, Gudrun Wanner, M. Hueller, N. Meshksar, L. Mendes, P. Pivato, Juan Ramos-Castro, Karsten Danzmann, Davor Mance, J. Martino, A. M. Cruise, D. Bortoluzzi, Nikolaos Karnesis, Michael Perreur-Lloyd, Miquel Nofrarías, José F. F. Mendes, Antoine Petiteau, D. Texier, Paul McNamara, M. Born, M. Hewitson, Carlos F. Sopuerta, Lluis Gesa, B. Kaune, Ingo Diepholz, R. Maarschalkerweerd, A. Wittchen, Eric Plagnol, Víctor S. Martín, Catia Grimani, Ivan Lloro, J. Reiche, A. Cesarini, G. Russano, D. I. Robertson, Daniel Hollington, S. Vitale, T. J. Sumner, L. Liu, E. Castelli, J. A. Lobo, Christian J. Killow, G. Dixon, Pierre Binétruy, Heather Audley, Ignacio Mateos, LISA Pathfinder Collaboration, Science and Technology Facilities Council (STFC), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), LISA Pathfinder, Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Astrofísica, noise, Gravitational-wave observatory, Geodesic, FOS: Physical sciences, Astronomy & Astrophysics, Astrophysics, 01 natural sciences, Noise (electronics), Star tracker, Gravitational waves, Physics, Particles & Fields, Attitude control, cosmic rays, 0103 physical sciences, Experiments in gravity, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Aerospace engineering, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, LISA, Science & Technology, Spacecraft, 010308 nuclear & particles physics, Gravitational wave, business.industry, stability, Pathfinder, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], Physical Sciences, business, Astrophysics - Instrumentation and Methods for Astrophysics, cosmology, geodesic, performance
Abstract: The science operations of the LISA Pathfinder mission has demonstrated the feasibility of sub-femto-g free-fall of macroscopic test masses necessary to build a LISA-like gravitational wave observatory in space. While the main focus of interest, i.e. the optical axis or the $x$-axis, has been extensively studied, it is also of interest to evaluate the stability of the spacecraft with respect to all the other degrees of freedom. The current paper is dedicated to such a study, with a focus set on an exhaustive and quantitative evaluation of the imperfections and dynamical effects that impact the stability with respect to its local geodesic. A model of the complete closed-loop system provides a comprehensive understanding of each part of the in-loop coordinates spectra. As will be presented, this model gives very good agreements with LISA Pathfinder flight data. It allows one to identify the physical noise source at the origin and the physical phenomena underlying the couplings. From this, the performances of the stability of the spacecraft, with respect to its geodesic, are extracted as a function of frequency. Close to $1 mHz$, the stability of the spacecraft on the $X_{SC}$, $Y_{SC}$ and $Z_{SC}$ degrees of freedom is shown to be of the order of $5.0\ 10^{-15} m\ s^{-2}/\sqrt{Hz}$ for X and $4.0 \ 10^{-14} m\ s^{-2}/\sqrt{Hz}$ for Y and Z. For the angular degrees of freedom, the values are of the order $3\ 10^{-12} rad\ s^{-2}/\sqrt{Hz}$ for $\Theta_{SC}$ and $3\ 10^{-13} rad\ s^{-2}/\sqrt{Hz}$ for $H_{SC}$ and $\Phi_{SC}$., Comment: 16 pages, 10 figures
Published: 2019

10. Forbush decreases and <2 day GCR flux non-recurrent variations studied with LISA pathfinder

Author: N. Korsakova, Jacob Slutsky, Valerio Ferroni, D. Hoyland, Ian Harrison, Henri Inchauspe, Monica Laurenza, J. Grzymisch, Davor Mance, Ph. Jetzer, H. Ward, E. D. Fitzsimons, D. Texier, R. Giusteri, W. J. Weber, Gerhard Heinzel, Antoine Petiteau, Paul McNamara, Ignacio Mateos, Lluis Gesa, Ivan Lloro, Carlos F. Sopuerta, Rita Dolesi, D. I. Robertson, Martin Hewitson, Domenico Giardini, Daniel Hollington, J. Martino, J. P. López-Zaragoza, B. Kaune, M. Hueller, Daniele Vetrugno, J. A. Lobo, Michael Perreur-Lloyd, Ferran Gibert, R. Maarschalkerweerd, M. Born, Víctor S. Martín, L. Martin-Polo, James Ira Thorpe, P. Pivato, Luigi Ferraioli, A. Wittchen, Stefano Vitale, F. Rivas, M. Fabi, Gudrun Wanner, Juan Ramos-Castro, José F. F. Mendes, A. Cesarini, G. Russano, Heather Audley, Peter Wass, Eric Plagnol, Ingo Diepholz, N. Finetti, Karsten Danzmann, Pierre Binétruy, L. Wissel, Antonella Cavalleri, Peter Zweifel, Daniele Bortoluzzi, L. Mendes, J. Reiche, Miquel Nofrarías, J. Baird, Michele Armano, M. Freschi, S. Paczkowski, A. M. Cruise, N. Karnesis, Simone Benella, Mattia Villani, F. Martin-Porqueras, N. Meshksar, Daniele Telloni, Oliver Jennrich, Karel Kudela, T. J. Sumner, L. Liu, E. Castelli, M. de Deus Silva, Catia Grimani, Christian J. Killow, G. Dixon, Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)
Subjects: Ciències de la visió::Òptica física [Àrees temàtiques de la UPC], PARTICLE-ACCELERATION, solar–terrestrial relations, 010504 meteorology & atmospheric sciences, Energies::Energia solar fotovoltaica [Àrees temàtiques de la UPC], Flux, Astrophysics, Photovoltaic power generation, 01 natural sciences, 0305 Organic Chemistry, Heliosphere, Physics - Space Physics, Interferòmetres, instrumentation: interferometers, 010303 astronomy & astrophysics, Solar–terrestrial relations, Energia solar fotovoltaica, Physics, 0306 Physical Chemistry (incl. Structural), COROTATING INTERACTION REGIONS, heliosphere [Sun], Sun, solar-terrestrial relations, interferometers, interplanetary medium, Sun: heliosphere [cosmic rays, instrumentation], COSMIC-RAY PROTON, Astrophysics - Solar and Stellar Astrophysics, SOLAR-WIND, Physical Sciences, Lagrangian point, Astronomy & Astrophysics, Interferometers [Instrumentation], cosmic rays, 0103 physical sciences, 0201 Astronomical and Space Sciences, MODULATION, FIELD, Sun: heliosphere, Cosmic rays, 0105 earth and related environmental sciences, Geomagnetic storm, SPECTRUM, Science & Technology, Interferometers, Astronomy and Astrophysics, Plasma, Pathfinder, 13. Climate action, Space and Planetary Science, Heliospheric current sheet, Interplanetary spaceflight, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Intensity (heat transfer), Interplanetary medium, Astrophysics - Earth and Planetary Astrophysics
Abstract: International audience; Non-recurrent short-term variations of the galactic cosmic-ray (GCR) flux above 70 MeV n−1 were observed between 2016 February 18 and 2017 July 3 on board the European Space Agency LISA Pathfinder (LPF) mission orbiting around the Lagrange point L1 at 1.5 × 106 km from Earth. The energy dependence of three Forbush decreases is studied and reported here. A comparison of these observations with others carried out in space down to the energy of a few tens of MeV n−1 shows that the same GCR flux parameterization applies to events of different intensity during the main phase. FD observations in L1 with LPF and geomagnetic storm occurrence are also presented. Finally, the characteristics of GCR flux non-recurrent variations (peaks and depressions) of duration
Published: 2019

11. LISA Pathfinder Performance Confirmed in an Open-Loop Configuration: Results from the Free-Fall Actuation Mode

Author: N. Korsakova, M. de Deus Silva, Lluis Gesa, Gerhard Heinzel, W. J. Weber, Daniele Bortoluzzi, L. Mendes, J. Grzymisch, James Ira Thorpe, Ph. Jetzer, Miquel Nofrarías, H. Ward, Jacob Slutsky, Valerio Ferroni, R. Maarschalkerweerd, A. Cesarini, G. Russano, D. Hoyland, J. Baird, D. I. Robertson, Domenico Giardini, I. Harrison, Peter Zweifel, M. Born, Antoine Petiteau, Mauro Hueller, Rita Dolesi, Peter Wass, Oliver Jennrich, A. M. Cruise, Paul McNamara, J. Martino, Davor Mance, G. Dixon, Karsten Danzmann, J. Reiche, D. Texier, Ingo Diepholz, S. Vitale, Michael Perreur-Lloyd, L. Wissel, M. S. Hartig, Nikolaos Karnesis, Carlos F. Sopuerta, F. Rivas, R. Giusteri, E. D. Fitzsimons, Christian J. Killow, Daniele Vetrugno, Heather Audley, N. Meshksar, A. Wittchen, Eric Plagnol, V. Martín, Gudrun Wanner, Catia Grimani, Juan Ramos-Castro, B. Kaune, Michele Armano, Antonella Cavalleri, L. Martin-Polo, M. Freschi, P. Pivato, Pierre Binétruy, T. J. Sumner, L. Liu, E. Castelli, José F. F. Mendes, M. Hewitson, F. Martin-Porqueras, J. P. López-Zaragoza, Ignacio Mateos, Ferran Gibert, Luigi Ferraioli, Daniel Hollington, J. A. Lobo, S. Paczkowski, H. Inchauspe, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Science and Technology Facilities Council (STFC), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, and 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)
Subjects: General Physics, Physics, Multidisciplinary, FOS: Physical sciences, General Physics and Astronomy, Actuation noise, Impulse (physics), Gravitation and Astrophysics, 01 natural sciences, LISA Pathfinder, Article, Atomic physics, Gravitational waves, Física::Electromagnetisme::Radiació infraroja, visible i ultraviolada [Àrees temàtiques de la UPC], Physics - Space Physics, Ones gravitacionals, Control theory, Force calibration, 0103 physical sciences, ddc:530, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, Science & Technology, 02 Physical Sciences, Noise measurement, Gravitational wave, Noise measurements, article, Open-loop controller, noise measurement, Dominant factor, acceleration, Space physics, calibration, Space Physics (physics.space-ph), Pathfinder, Mode of operations, Physical Sciences, Differential accelerations, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, Open-loop configuration, Astrophysics - Instrumentation and Methods for Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Space probes, Quasistatic process
Abstract: We report on the results of the LISA Pathfinder (LPF) free-fall mode experiment, in which the control force needed to compensate the quasistatic differential force acting on two test masses is applied intermittently as a series of "impulse" forces lasting a few seconds and separated by roughly 350 s periods of true free fall. This represents an alternative to the normal LPF mode of operation in which this balancing force is applied continuously, with the advantage that the acceleration noise during free fall is measured in the absence of the actuation force, thus eliminating associated noise and force calibration errors. The differential acceleration noise measurement presented here with the free-fall mode agrees with noise measured with the continuous actuation scheme, representing an important and independent confirmation of the LPF result. An additional measurement with larger actuation forces also shows that the technique can be used to eliminate actuation noise when this is a dominant factor. © 2019 authors. Published by the American Physical Society.
Published: 2019

12. Novel methods to measure the gravitational constant in space

Author: J. P. López-Zaragoza, Ferran Gibert, S. Paczkowski, Antoine Petiteau, Paul McNamara, J. A. Lobo, Luigi Ferraioli, L. Wissel, Domenico Giardini, F. Rivas, Gerhard Heinzel, W. J. Weber, Daniele Bortoluzzi, L. Mendes, Carlos F. Sopuerta, B. Kaune, Gudrun Wanner, M. S. Hartig, N. Meshksar, Miquel Nofrarías, Juan Ramos-Castro, Víctor S. Martín, F. Martin-Porqueras, Daniele Vetrugno, M. de Deus Silva, Daniel Hollington, Davor Mance, Pierre Binétruy, T. J. Sumner, L. Liu, A. M. Cruise, Ph. Jetzer, Lluis Gesa, D. Texier, E. Castelli, Christian J. Killow, Jacob Slutsky, Valerio Ferroni, James Ira Thorpe, R. Maarschalkerweerd, J. Baird, A. Wittchen, Antonella Cavalleri, P. Pivato, José F. F. Mendes, J. Reiche, D. Hoyland, E. D. Fitzsimons, A. Cesarini, G. Russano, Nikolaos Karnesis, M. Born, N. Korsakova, Michael Perreur-Lloyd, R. Giusteri, Eric Plagnol, Karsten Danzmann, Catia Grimani, G. Dixon, S. Vitale, M. Hewitson, Ingo Diepholz, Peter Zweifel, Peter Wass, Rita Dolesi, L. Martin-Polo, J. Grzymisch, H. Ward, D. I. Robertson, Michele Armano, M. Freschi, J. Martino, C. Trenkel, Ian Harrison, Henri Inchauspe, M. Hueller, Heather Audley, Oliver Jennrich, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), LISA Pathfinder, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, and 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)
Subjects: Astrofísica, Physics, 010308 nuclear & particles physics, General physics, Mechanics, Astrophysics, Space (mathematics), 01 natural sciences, Measure (mathematics), Cosmology, Laboratory studies of gravity, Gravitation, Gravitational constant, Acceleration, Pathfinder, cosmic rays, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], 0103 physical sciences, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Experiments in gravity, 010306 general physics, Suspension (vehicle), cosmology, Cosmology and astrophysics
Abstract: International audience; We present two novel methods, tested by LISA Pathfinder, to measure the gravitational constant G for the first time in space. Experiment 1 uses electrostatic suspension forces to measure a change in acceleration of a test mass due to a displaced source mass. Experiment 2 measures a change in relative acceleration between two test masses due to a slowly varying fuel tank mass. Experiment 1 gave a value of G=6.71±0.42(×10-11) m3 s-2 kg-1 and experiment 2 gave 6.15±0.35(×10-11) m3 s-2 kg-1, both consistent with each other to 1σ and with the CODATA 2014 recommended value of 6.67408±0.00031(×10-11) m3 s-2 kg-1 to 2σ. We outline several ideas to improve the results for a future experiment, and we suggest that a measurement in space would isolate many terrestrial issues that could be responsible for the inconsistencies between recent measurements.
Published: 2019

13. Micrometeoroid Events in LISA Pathfinder

Author: Ignacio Mateos, St Drs Operations Team, J. Grzymisch, H. Ward, D. Wealthy, H. Rozemeijer, J. A. Lobo, Gerhard Heinzel, Nicole Pagane, A. Zambotti, S. Paczkowski, Ivan Lloro, Ph. Jetzer, Antoine Petiteau, Paul McNamara, P. Prat, José F. F. Mendes, Daniele Bortoluzzi, N. Brandt, Nikolaos Karnesis, James Ira Thorpe, R. De Rosa, Michael Tröbs, Carlos F. Sopuerta, Michele Armano, L. Mendes, C. Zanoni, Davor Mance, J. O’Donnell, Daniele Vetrugno, B. Johlander, Lluis Gesa, G. Auger, Curt Cutler, John Ziemer, M. Freschi, Henri Inchauspe, A. Schleicher, F. Martin-Porqueras, M. Girard, M. Hewitson, D. Shaul, R. Maarschalkerweerd, Karsten Danzmann, T. J. Sumner, D. Texier, E. D. Fitzsimons, F. Rivas, Daniel Hollington, L. Liu, Oliver Jennrich, Miquel Nofrarías, P. Pivato, A. M. Cruise, W. J. Weber, R. Giusteri, Michael Perreur-Lloyd, John G. Baker, P. Sarra, Tobias Ziegler, N. Korsakova, Aniello Grado, Heather Audley, Peter Wass, Tyson Littenberg, Gudrun Wanner, Sophie Hourihane, Pierre Binétruy, Antonella Cavalleri, L. Di Fiore, R. Gerndt, Jacob Slutsky, Valerio Ferroni, S. Vitale, Christian J. Killow, B. Kaune, C. Trenkel, S. Madden, Diego Janches, Juan Ramos-Castro, D. Hoyland, C. Marrese-Reading, J. Reiche, Rita Dolesi, N. Dunbar, Catia Grimani, P. Barela, C. Dunn, C. García Marirrodriga, A. Wittchen, R. Flatscher, P. Maghami, U. Ragnit, I. Li, Ruggero Stanga, Mauro Hueller, Nate Demmons, S. Javidnia, Petr Pokorny, G. Dixon, J. P. López-Zaragoza, M. Born, A. Cesarini, G. Russano, Ferran Gibert, J. Martino, J. Baird, Massimo Bassan, O. Hsu, Andrew Romero-Wolf, L. Wissel, Ingo Diepholz, M. de Deus Silva, Luigi Ferraioli, Eric Plagnol, V. Martín, Domenico Giardini, M. Caleno, D. I. Robertson, Peter Zweifel, J. Mehta, L. Martin-Polo, I. Harrison, Thorpe, J. I., Slutsky, J., Baker, J. G., Littenberg, T. B., Hourihane, S., Pagane, N., Pokorny, P., Janches, D., Armano, M., Audley, H., Auger, G., Baird, J., Bassan, M., Binetruy, P., Born, M., Bortoluzzi, D., Brandt, N., Caleno, M., Cavalleri, A., Cesarini, A., Cruise, A. M., Danzmann, K., De Deus Silva, M., DE ROSA, Rosario, Di Fiore, L., Diepholz, I., Dixon, G., Dolesi, R., Dunbar, N., Ferraioli, L., Ferroni, V., Fitzsimons, E. D., Flatscher, R., Freschi, M., Garcia Marirrodriga, C., Gerndt, R., Gesa, L., Gibert, F., Giardini, D., Giusteri, R., Grado, A., Grimani, C., Grzymisch, J., Harrison, I., Heinzel, G., Hewitson, M., Hollington, D., Hoyland, D., Hueller, M., Inchauspe, H., Jennrich, O., Jetzer, P., Johlander, B., Karnesis, N., Kaune, B., Korsakova, N., Killow, C. J., Lobo, J. A., Lloro, I., Liu, L., Lopez-Zaragoza, J. P., Maarschalkerweerd, R., Mance, D., Martin, V., Martin-Polo, L., Martino, J., Martin-Porqueras, F., Madden, S., Mateos, I., Mcnamara, P. W., Mendes, J., Mendes, L., Nofrarias, M., Paczkowski, S., Perreur-Lloyd, M., Petiteau, A., Pivato, P., Plagnol, E., Prat, P., Ragnit, U., Ramos-Castro, J., Reiche, J., Robertson, D. I., Rozemeijer, H., Rivas, F., Russano, G., Sarra, P., Schleicher, A., Shaul, D., Sopuerta, C. F., Stanga, R., Sumner, T., Texier, D., Trenkel, C., Trobs, M., Vetrugno, D., Vitale, S., Wanner, G., Ward, H., Wass, P., Wealthy, D., Weber, W. J., Wissel, L., Wittchen, A., Zambotti, A., Zanoni, C., Ziegler, T., Zweifel, P., Barela, P., Cutler, C., Demmons, N., Dunn, C., Girard, M., Hsu, O., Javidnia, S., Li, I., Maghami, P., Marrese-Reading, C., Mehta, J., Romero-Wolf, A., Ziemer, J., AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-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), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, and Science and Technology Facilities Council (STFC)
Subjects: Astrofísica, Solar System, 010504 meteorology & atmospheric sciences, Meteors, Astrophysics, 01 natural sciences, Planet, meteoroids, 010303 astronomy & astrophysics, Earth and Planetary Astrophysics (astro-ph.EP), 0306 Physical Chemistry (incl. Structural), Settore FIS/01, Physics, Sistema solar, education.field_of_study, Micrometeoroid, Astrophysics::Instrumentation and Methods for Astrophysics, Meteoroids, instrumentation: miscellaneous, meteorites, meteors, meteoroids, Asteroid, Physical Sciences, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, miscellaneous [Instrumentation], Solar system, Population, FOS: Physical sciences, Astronomy & Astrophysics, meteorites, 0201 Astronomical and Space Sciences, 0103 physical sciences, meteors, education, 0105 earth and related environmental sciences, Science & Technology, Zodiacal light, Meteoroid, instrumentation: miscellaneou, Astronomy, Astronomy and Astrophysics, miscellaneous, meteorites, meteors, meteoroids [instrumentation], Pathfinder, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], Enginyeria electrònica::Instrumentació i mesura [Àrees temàtiques de la UPC], ORBITS, Astrophysics - Earth and Planetary Astrophysics, Meteorites
Abstract: The zodiacal dust complex, a population of dust and small particles that pervades the Solar System, provides important insight into the formation and dynamics of planets, comets, asteroids, and other bodies. Here we present a new set of data obtained using a novel technique: direct measurements of momentum transfer to a spacecraft from individual particle impacts. This technique is made possible by the extreme precision of the instruments flown on the LISA Pathfinder spacecraft, a technology demonstrator for a future space-based gravitational wave observatory that operated near the first Sun-Earth Lagrange point from early 2016 through Summer of 2017. Using a simple model of the impacts and knowledge of the control system, we show that it is possible to detect impacts and measure properties such as the transferred momentum (related to the particle's mass and velocity), direction of travel, and location of impact on the spacecraft. In this paper, we present the results of a systematic search for impacts during 4348 hours of Pathfinder data. We report a total of 54 candidates with momenta ranging from 0.2$\,\mu\textrm{Ns}$ to 230$\,\mu\textrm{Ns}$. We furthermore make a comparison of these candidates with models of micrometeoroid populations in the inner solar system including those resulting from Jupiter-family comets, Oort-cloud comets, Hailey-type comets, and Asteroids. We find that our measured population is consistent with a population dominated by Jupiter-family comets with some evidence for a smaller contribution from Hailey-type comets. This is in agreement with consensus models of the zodiacal dust complex in the momentum range sampled by LISA Pathfinder., Comment: 22 pages, 14 figures, accepted in ApJ
Published: 2019

14. LISA Pathfinder micronewton cold gas thrusters: In-flight characterization

Author: Nikolaos Karnesis, N. Korsakova, Jacob Slutsky, Valerio Ferroni, Daniele Vetrugno, Davor Mance, S. Paczkowski, D. Texier, Henri Inchauspe, G. Dixon, Ivan Lloro, D. Hoyland, Luigi Ferraioli, M. de Deus Silva, P. Pivato, L. Wissel, Ignacio Mateos, J. Grzymisch, Ph. Jetzer, P. Zweifel, Antonella Cavalleri, T. J. Sumner, L. Liu, N. Meshksar, Daniele Bortoluzzi, L. Mendes, Peter Wass, E. Castelli, F. Rivas, E. D. Fitzsimons, Pierre Binétruy, Lluis Gesa, S. Vitale, Heather Audley, F. Martin-Porqueras, R. Giusteri, J. Martino, A. M. Cruise, Michele Armano, R. Maarschalkerweerd, D. I. Robertson, A. Wittchen, Antoine Petiteau, Paul McNamara, Daniel Hollington, Gudrun Wanner, Miquel Nofrarías, Juan Ramos-Castro, M. Freschi, Catia Grimani, Carlos F. Sopuerta, Christian J. Killow, J. Baird, M. Hueller, Oliver Jennrich, Rita Dolesi, M. Born, Eric Plagnol, Domenico Giardini, J. A. Lobo, James Ira Thorpe, Ingo Diepholz, José F. F. Mendes, J. Reiche, A. Cesarini, G. Russano, M. Hewitson, W. J. Weber, L. Martin-Polo, H. Ward, I. Harrison, Michael Perreur-Lloyd, J. P. López-Zaragoza, Karsten Danzmann, Ferran Gibert, B. Kaune, Víctor S. Martín, Gerhard Heinzel, AstroParticule et Cosmologie (APC (UMR_7164)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), LISA Pathfinder, Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-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), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)
Subjects: Inertial frame of reference, Gravitational-wave observatory, noise: low, satellite, Propulsion, 01 natural sciences, 7. Clean energy, Gravitational waves, cosmic rays, Ones gravitacionals, gas, 0103 physical sciences, Experiments in gravity, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Aerospace engineering, Física::Relativitat::Gravitació [Àrees temàtiques de la UPC], 010306 general physics, accelerator: design, Physics, LISA, Spacecraft, 010308 nuclear & particles physics, business.industry, electronics, Astrophysics::Instrumentation and Methods for Astrophysics, stability, Metrology, Pathfinder, Harmonics, Physics::Space Physics, control system, business, cosmology, performance, Space environment, ejection
Abstract: International audience; The LISA Pathfinder (LPF) mission has demonstrated the ability to limit and measure the fluctuations in acceleration between two free falling test masses down to sub-femto-g levels. One of the key elements to achieve such a level of residual acceleration is the drag free control. In this scheme the spacecraft is used as a shield against any external disturbances by adjusting its relative position to a reference test mass. The actuators used to move the spacecraft are cold gas micropropulsion thrusters. In this paper, we report in-flight characterization of these thrusters in term of noise and artefacts during science operations using all the metrology capabilities of LISA Pathfinder. Using the LISA Pathfinder test masses as an inertial reference frame, an average thruster noise of ∼0.17 μN/Hz is observed and decomposed into a common (coherent) and an uncorrelated component. The very low noise and stability of the onboard metrology system associated with the quietness of the space environment allowed the measurement of the thruster noise down to ∼20 μHz, more than an order of magnitude below any ground measurement. Spectral lines were observed around ∼1.5 mHz and its harmonics and around 55 and 70 mHz. They are associated with the cold gas system itself and possibly to a clock synchronization issue. The thruster noise-floor exhibits an excess of ∼70% compared to characterization that have been made on ground on a single unit and without the feeding system. However this small excess has no impact on the LPF mission performance and is compatible with the noise budget for the upcoming LISA gravitational wave observatory. Over the whole mission, nominal, and extension, the thrusters showed remarkable stability for both the science operations and the different maneuvers necessary to maintain LPF on its orbit around L1. It is therefore concluded that a similar cold gas system would be a viable propulsion system for the future LISA mission.
Published: 2019

15. Temperature stability in the sub-milliHertz band with LISA Pathfinder

Author: Ferran Gibert, A. Cesarini, G. Russano, Peter Zweifel, Daniele Vetrugno, F. Rivas, S. Vitale, Michael Perreur-Lloyd, A. Wittchen, P. Pivato, Jacob Slutsky, Valerio Ferroni, Pierre Binétruy, Mauro Hueller, Gudrun Wanner, D. Hoyland, B. Kaune, C. Trenkel, Antoine Petiteau, Juan Ramos-Castro, Gerhard Heinzel, Daniel Hollington, G. Dixon, Paul McNamara, Ivan Lloro, R. Giusteri, Carlos F. Sopuerta, Davor Mance, Ph. Jetzer, M. Born, D. Texier, C. Mansanet, D. I. Robertson, Domenico Giardini, Antonella Cavalleri, Rita Dolesi, Ingo Diepholz, L. Martin-Polo, T. J. Sumner, L. Liu, J. Martino, D. Wealthy, Karsten Danzmann, Peter Wass, Heather Audley, E. Castelli, L. Wissel, Luigi Ferraioli, J. Baird, Ignacio Mateos, Christian J. Killow, Michele Armano, N. Korsakova, I. Harrison, N. Meshksar, J. A. Lobo, M. Freschi, S. Paczkowski, E. D. Fitzsimons, Eric Plagnol, V. Martín, Nikolaos Karnesis, J. Grzymisch, H. Ward, José F. F. Mendes, W. J. Weber, M. Hewitson, Oliver Jennrich, J. Reiche, Lluis Gesa, H. Inchauspé, Jose Sanjuan, James Ira Thorpe, R. Maarschalkerweerd, Catia Grimani, M. de Deus Silva, F. Martin-Porqueras, Daniele Bortoluzzi, L. Mendes, A. M. Cruise, Miquel Nofrarías, J. P. López-Zaragoza, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), LISA Pathfinder, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, and 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)
Subjects: detector: satellite, interferometer, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Low frequency, 01 natural sciences, Transfer function, Temperature measurement, General Relativity and Quantum Cosmology, Gravitational waves, temperature: fluctuation, Instruments [Space vehicles], Ones gravitacionals, 0103 physical sciences, noise: thermal, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Física::Relativitat::Gravitació [Àrees temàtiques de la UPC], space vehicles: instruments, Aerospace engineering, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, LISA, 010308 nuclear & particles physics, Gravitational wave, business.industry, gravitational radiation, Time evolution, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, gravitational radiation detector, Interferometry, frequency: low, Pathfinder, gravitational waves, gravitational waves – space vehicles: instruments, Space and Planetary Science, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], temperature: stability, Astrophysics - Instrumentation and Methods for Astrophysics, Aeronàutica i espai::Astronàutica [Àrees temàtiques de la UPC], business, Noise (radio)
Abstract: LISA Pathfinder (LPF) was a technology pioneering mission designed to test key technologies required for gravitational wave detection in space. In the low frequency regime (milli-Hertz and below), where space-based gravitational wave observatories will operate, temperature fluctuations play a crucial role since they can couple into the interferometric measurement and the test masses' free-fall accuracy in many ways. A dedicated temperature measurement subsystem, with noise levels in 10$\,\mu$K$\,$Hz$^{-1/2}$ down to $1\,$mHz was part of the diagnostics unit on board LPF. In this paper we report on the temperature measurements throughout mission operations, characterize the thermal environment, estimate transfer functions between different locations and report temperature stability (and its time evolution) at frequencies as low as 10$\,\mu$Hz, where typically values around $1\,$K$\,$Hz$^{-1/2}$ were measured., Comment: 13 pages, 16 figures. MNRAS LaTeX style file version 3.0
Published: 2019

16. Precision charge control for isolated free-falling test masses: LISA pathfinder results

Author: J. Martino, Domenico Giardini, Antoine Petiteau, Paul McNamara, Ian Harrison, S. Paczkowski, Carlos F. Sopuerta, Eric Plagnol, B. Kaune, Peter Wass, Henri Inchauspe, N. Korsakova, D. I. Robertson, Víctor S. Martín, J. Baird, Daniele Vetrugno, N. Meshskar, P. Sarra, Oliver Jennrich, T. J. Sumner, L. Liu, Ph. Jetzer, E. Castelli, J. Grzymisch, Gerhard Heinzel, S. Vitale, D. Shaul, H. Ward, P. Pivato, F. Rivas, Jacob Slutsky, Valerio Ferroni, G. Santoruvo, Michele Armano, Catia Grimani, M. Hueller, D. Hoyland, G. Dixon, M. Freschi, Ignacio Mateos, Lluis Gesa, Karsten Danzmann, Michael Perreur-Lloyd, Pierre Binétruy, Daniel Hollington, Nikolaos Karnesis, W. J. Weber, R. Maarschalkerweerd, M. de Deus Silva, F. Martin-Porqueras, P. Zweifel, Antonella Cavalleri, A. Wittchen, Gudrun Wanner, J. A. Lobo, Juan Ramos-Castro, James Ira Thorpe, Luigi Ferraioli, E. D. Fitzsimons, Heather Audley, R. Giusteri, M. Born, L. Wissel, Christian J. Killow, Markus Pfeil, Rita Dolesi, S. Waschke, L. Mendes, Ingo Diepholz, José F. F. Mendes, A. M. Cruise, M. Hewitson, D. Bortoluzzi, Miquel Nofrarías, J. P. López-Zaragoza, Ferran Gibert, L. Martin-Polo, J. Reiche, A. Cesarini, G. Russano, Davor Mance, D. Texier, Ivan Lloro, F. Mailland, C. Trenkel, AstroParticule et Cosmologie (APC (UMR_7164)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), LISA, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-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), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), LISA Pathfinder Collaboration, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica
Subjects: Physics - Instrumentation and Detectors, Physics and Astronomy (miscellaneous), 7. Clean energy, 01 natural sciences, Physics, Particles & Fields, Gravitational wave detectors, Software, MATLAB, physics.ins-det, MISSION, computer.programming_language, Physics, Instrumentation and Detectors (physics.ins-det), 3. Good health, cosmic radiation, Physical Sciences, GEANT, charge: surface, Física::Relativitat [Àrees temàtiques de la UPC], photoelectron, Experimental studies of gravity, FOS: Physical sciences, Astronomy & Astrophysics, Electric charge, Charge, electric field: effect, Gravitational waves, cosmic rays, Ones gravitacionals, photon: irradiation, Electric field, 0103 physical sciences, Charge control, Experiments in gravity, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010306 general physics, GEANT4, Science & Technology, charge: electric, 010308 nuclear & particles physics, Gravitational wave, business.industry, Charge (physics), FIELDS, charge: induced, Computational physics, Pathfinder, business, cosmology, computer
Abstract: International audience; The LISA Pathfinder charge management device was responsible for neutralizing the cosmic-ray-induced electric charge that inevitably accumulated on the free-falling test masses at the heart of the experiment. We present measurements made on ground and in flight that quantify the performance of this contactless discharge system which was based on photoemission under UV illumination. In addition, a two-part simulation is described that was developed alongside the hardware. Modeling of the absorbed UV light within the Pathfinder sensor was carried out with the Geant4 software toolkit and a separate Matlab charge transfer model calculated the net photocurrent between the test masses and surrounding housing in the presence of AC and DC electric fields. We confront the results of these models with observations and draw conclusions for the design of discharge systems for future experiments like LISA that will also employ free-falling test masses.
Published: 2018

17. Calibrating the system dynamics of LISA Pathfinder

Author: J. Grzymisch, H. Ward, W. J. Weber, Christian J. Killow, Ignacio Mateos, M. de Deus Silva, S. Paczkowski, Pierre Binétruy, Eric Plagnol, J. Reiche, J. P. López-Zaragoza, N. Korsakova, Gerhard Heinzel, N. Meshksar, J. Martino, A. Cesarini, G. Russano, F. Rivas, Domenico Giardini, G. Dixon, Antonella Cavalleri, Ferran Gibert, Catia Grimani, Ian Harrison, T. J. Sumner, Oliver Jennrich, Henri Inchauspe, Antoine Petiteau, Gudrun Wanner, L. Liu, Paul McNamara, Michael Perreur-Lloyd, Peter Zweifel, Juan Ramos-Castro, L. Martin-Polo, E. Castelli, Carlos F. Sopuerta, Lluis Gesa, J. Baird, Heather Audley, R. Maarschalkerweerd, José F. F. Mendes, Jacob Slutsky, Valerio Ferroni, Daniele Vetrugno, A. Wittchen, M. Hueller, M. Hewitson, D. Hoyland, S. Vitale, A. M. Cruise, Nikolaos Karnesis, B. Kaune, P. Pivato, Davor Mance, D. Texier, D. I. Robertson, Luigi Ferraioli, M. Born, Víctor S. Martín, James Ira Thorpe, F. Martin-Porqueras, Ph. Jetzer, L. Wissel, Daniele Bortoluzzi, L. Mendes, Karsten Danzmann, Miquel Nofrarías, Daniel Hollington, J. A. Lobo, Michele Armano, M. Freschi, Peter Wass, Ivan Lloro, R. Giusteri, Rita Dolesi, E. D. Fitzsimons, Ingo Diepholz, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: noise, detector: performance, detector: satellite, FOS: Physical sciences, Astronomy & Astrophysics, Residual, 01 natural sciences, Physics, Particles & Fields, INTERFEROMETRY, Acceleration, 0103 physical sciences, Calibration, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Aerospace engineering, 010306 general physics, Instrumentation and Methods for Astrophysics (astro-ph.IM), MISSION, Physics, LISA, Science & Technology, Spacecraft, 010308 nuclear & particles physics, Noise (signal processing), business.industry, Gravitational wave, gravitational radiation, Astrophysics::Instrumentation and Methods for Astrophysics, acceleration, stability, calibration, gravitational radiation detector, System dynamics, Pathfinder, Physical Sciences, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], readout, business, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: International audience; LISA Pathfinder (LPF) was a European Space Agency mission with the aim to test key technologies for future space-borne gravitational-wave observatories like LISA. The main scientific goal of LPF was to demonstrate measurements of differential acceleration between free-falling test masses at the sub-femto-g level, and to understand the residual acceleration in terms of a physical model of stray forces, and displacement readout noise. A key step toward reaching the LPF goals was the correct calibration of the dynamics of LPF, which was a three-body system composed by two test-masses enclosed in a single spacecraft, and subject to control laws for system stability. In this work, we report on the calibration procedures adopted to calculate the residual differential stray force per unit mass acting on the two test-masses in their nominal positions. The physical parameters of the adopted dynamical model are presented, together with their role on LPF performance. The analysis and results of these experiments show that the dynamics of the system was accurately modeled and the dynamical parameters were stationary throughout the mission. Finally, the impact and importance of calibrating system dynamics for future space-based gravitational wave observatories is discussed.
Published: 2018

18. Beyond the required LISA free-fall performance: new LISA Pathfinder results down to 20 μHz

Author: Daniele Vetrugno, Oliver Jennrich, P. Pivato, Daniele Bortoluzzi, L. Mendes, Ph. Jetzer, Gerhard Heinzel, L. Martin-Polo, Miquel Nofrarías, Christian J. Killow, Pierre Binétruy, Antoine Petiteau, Ivan Lloro, N. Meshksar, Paul McNamara, E. D. Fitzsimons, Daniel Hollington, A. Cesarini, G. Russano, Carlos F. Sopuerta, Karsten Danzmann, R. Giusteri, Salvatore Vitale, Luigi Ferraioli, T. J. Sumner, L. Liu, Lluis Gesa, Michael Perreur-Lloyd, Eric Plagnol, V. Martín, J. A. Lobo, Rita Dolesi, E. Castelli, S. Paczkowski, Jacob Slutsky, Valerio Ferroni, Peter Zweifel, B. Kaune, Mauro Hueller, Heather Audley, R. Maarschalkerweerd, Michele Armano, D. Hoyland, G. Dixon, A. Wittchen, M. Freschi, J. P. López-Zaragoza, Ferran Gibert, Peter Wass, José F. F. Mendes, Nikolaos Karnesis, Davor Mance, D. Texier, I. Harrison, D. I. Robertson, Ignacio Mateos, Antonella Cavalleri, M. Hewitson, Domenico Giardini, J. Martino, L. Wissel, N. Korsakova, J. Reiche, J. Grzymisch, H. Ward, F. Rivas, Gudrun Wanner, Juan Ramos-Castro, M. Born, Ingo Diepholz, James Ira Thorpe, J. Baird, Henri Inchauspe, W. J. Weber, F. Martin-Porqueras, A. M. Cruise, M. de Deus Silva, Catia Grimani, AstroParticule et Cosmologie (APC (UMR_7164)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Astrofísica, General Physics and Astronomy, Astrophysics, Noise figure, 01 natural sciences, 09 Engineering, LISA Pathfinder, pressure, benchmark, Noise performance, force: electrostatic, Physics, 02 Physical Sciences, Noise measurement, Brownian noise, Benchmarking, statistics, frequency, Physical Sciences, European Space Agency, Space probes, performance, General Physics, noise, perturbation, Physics, Multidisciplinary, Experimental benchmarks, calibration: electrostatic, Low frequency, Gravitational waves, Physics and Astronomy (all), Ones gravitacionals, 0103 physical sciences, ddc:530, noise: acceleration, 010306 general physics, 01 Mathematical Sciences, LISA, Science & Technology, 010308 nuclear & particles physics, Gravitational wave, Noise measurements, Física::Electromagnetisme::Ones electromagnètiques [Àrees temàtiques de la UPC], Low-frequency, Computational physics, Pathfinder, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], Differential accelerations, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract: In the months since the publication of the first results, the noise performance of LISA Pathfinder has improved because of reduced Brownian noise due to the continued decrease in pressure around the test masses, from a better correction of noninertial effects, and from a better calibration of the electrostatic force actuation. In addition, the availability of numerous long noise measurement runs, during which no perturbation is purposely applied to the test masses, has allowed the measurement of noise with good statistics down to 20 μHz. The Letter presents the measured differential acceleration noise figure, which is at (1.74±0.05) fm s−2/√Hz above 2 mHz and (6±1)×10 fm s−2/√Hz at 20 μHz, and discusses the physical sources for the measured noise. This performance provides an experimental benchmark demonstrating the ability to realize the low-frequency science potential of the LISA mission, recently selected by the European Space Agency., Physical Review Letters, 120 (6), ISSN:0031-9007, ISSN:1079-7114
Published: 2018

19. Characteristics and Energy Dependence of Recurrent Galactic Cosmic-Ray Flux Depressions and of a Forbush Decrease with LISA Pathfinder

Author: C. Zenoni, Lluis Gesa, J. Martino, A. Zambotti, Gerhard Heinzel, R. Maarschalkerweerd, A. Wittchen, I. Harrison, L. Martin-Polo, N. Korsakova, Stefano Vitale, Luis Mendes, J. A. Lobo, Marco Freschi, Nikolaos Karnesis, Jacob Slutsky, Valerio Ferroni, B. Kaune, D. Hoyland, Antoine Petiteau, L. Wissel, Daniele Bortoluzzi, Paul McNamara, T. J. Sumner, L. Liu, Pierre Binétruy, Carlos F. Sopuerta, Catia Grimani, Antonella Cavalleri, Ignacio Mateos, Heather Audley, Daniele Vetrugno, Miquel Nofrarías, J. Baird, Massimo Bassan, Monica Laurenza, Davor Mance, M. Born, Federico Sabbatini, F. Martin-Porqueras, James Ira Thorpe, Michele Armano, A. M. Cruise, Philippe Jetzer, E. D. Fitzsimons, Christian J. Killow, Karsten Danzmann, J. Grzymisch, H. Ward, J. Reiche, P. Pivato, D. I. Robertson, Henri Inchauspe, Ingo Diepholz, A. Cesarini, G. Russano, M. Fabi, M. de Deus Silva, Mauro Hueller, R. Giusteri, G. Dixon, Peter Wass, S. Paczkowski, N. Finetti, F. Rivas, Peter Zweifel, Rita Dolesi, Oliver Jennrich, Eric Plagnol, Michael Perreur-Lloyd, Gudrun Wanner, Domenico Giardini, Juan Ramos-Castro, Vicente Martín, Daniel Hollington, Simone Benella, Daniele Telloni, Ivan Lloro, J. P. López-Zaragoza, Ferran Gibert, Damien Texier, Luigi Ferraioli, José F. F. Mendes, M. Hewitson, W. J. Weber, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), AstroParticule et Cosmologie ( APC - UMR 7164 ), Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)
Subjects: Astrofísica, solar–terrestrial relations, 010504 meteorology & atmospheric sciences, 0306 Physical Chemistry (Incl. Structural), [ PHYS.ASTR ] Physics [physics]/Astrophysics [astro-ph], interferometers [instrumentation], Astrophysics, 01 natural sciences, 0305 Organic Chemistry, 27-DAY VARIATION, Physics - Space Physics, Coronal mass ejection, Astrophysics::Solar and Stellar Astrophysics, cosmic rays, instrumentation: interferometers, interplanetary medium, solar-terrestrial relations, Sun: heliosphere, Sun: rotation, 010303 astronomy & astrophysics, Sun rotation, Solar–terrestrial relations, [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Physics, High Energy Astrophysical Phenomena (astro-ph.HE), heliosphere [Sun], Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, Space physics, charged particle, solar, ELECTRONS, CORONAL MASS EJECTIONS, interferometers, Sun: rotation [cosmic rays, instrumentation], Astrophysics - Solar and Stellar Astrophysics, SOLAR-WIND, cosmic radiation: galaxy, Physical Sciences, Physics::Space Physics, Solar rotation, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, cosmic radiation: flux, Astrophysics::High Energy Astrophysical Phenomena, HELIOSPHERIC MODULATION, Interplanetary medium, FOS: Physical sciences, Cosmic ray, rotation [Sun], Astronomy & Astrophysics, 0103 physical sciences, PARTICLES, Forbush decrease, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], instrumentation interferometers, SPACED DATA, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Sun heliosphere, solar terrestrial relations, SPECTRUM, LISA, Science & Technology, cosmic radiation: energy spectrum, INTENSITY, POSITRONS, Astronomy and Astrophysics, Space Physics (physics.space-ph), cosmic rays, instrumentation interferometers, interplanetary medium, solar terrestrial relations, Sun heliosphere, Sun rotation, 0201 Astronomical And Space Sciences, monitoring, 13. Climate action, Space and Planetary Science, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], charged particle: detector, Interplanetary spaceflight, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Heliosphere
Abstract: The final publication is available at IOS Press through http://dx.doi.org/10.3847/1538-4357/aaa774 Galactic cosmic-ray (GCR) energy spectra observed in the inner heliosphere are modulated by the solar activity, the solar polarity and structures of solar and interplanetary origin. A high counting rate particle detector (PD) aboard LISA Pathfinder, meant for subsystems diagnostics, was devoted to the measurement of GCR and solar energetic particle integral fluxes above 70 MeV n-1 up to 6500 counts s-1. PD data were gathered with a sampling time of 15 s. Characteristics and energy dependence of GCR flux recurrent depressions and of a Forbush decrease dated 2016 August 2 are reported here. The capability of interplanetary missions, carrying PDs for instrument performance purposes, in monitoring the passage of interplanetary coronal mass ejections is also discussed.
Published: 2018

20. Experimental results from the ST7 mission on LISA Pathfinder

Author: S. Vitale, W. Warner, Lluis Gesa, J. Fernandez, Nikolaos Karnesis, M. Connally, R. Kolasinski, J. Martino, Thomas Randolph, Gerhard Heinzel, R. Maarschalkerweerd, A. Wittchen, J. Gorelik, Eric Ehrbar, S. Rhodes, Ian Harrison, J. Wellman, J. A. Lobo, Thomas Roy, O. Hsu, A. Carmain, Oliver Jennrich, G. Dixon, M. Cherng, Charley Dunn, Henri Inchauspe, Ivan Lloro, D. Miller, F. Rivas, Luigi Ferraioli, L. Chen, D. Kern, L. Markley, Heather Audley, José F. F. Mendes, E. Dorantes, Gudrun Wanner, Peter Wass, S. Paczkowski, T. Le, Juan Ramos-Castro, R. Valencia, Jacob Slutsky, Valerio Ferroni, William E. Connolly, Pierre Binétruy, L. Wissel, H. Umfress, R. Parikh, D. Hoyland, T. J. Sumner, John R. Anderson, L. Liu, M. Hewitson, L. Mendes, E. Castelli, Vlad Hruby, Antonella Cavalleri, N. Korsakova, O. Liepack, Shahram Javidnia, Miquel Nofrarías, John J. Evans, Michele Armano, C. Kuo, M. Freschi, Daniel Hollington, Garth Franklin, Douglas J. Jackson, G. Aveni, K. Blackman, M. Hueller, Christian J. Killow, M. S. Anderson, J. P. López-Zaragoza, M. Born, Ingo Diepholz, S. Malik, N. Meshksar, Ryan Martin, S. Clark, Nate Demmons, Douglas Spence, Ferran Gibert, J. Stocky, W. Tolman, Ignacio Mateos, D. Conroy, Ira Thorpe, G. Plett, Phil Barela, A. Littlefield, Peter Willis, J. D’Agostino, M. Cooper, A. M. Cruise, D. Bortoluzzi, Catia Grimani, M. Duran, M. de Deus Silva, H. Shaw, F. Martin-Porqueras, J. Reiche, A. Cesarini, G. Russano, J. Grzymisch, H. Ward, E. D. Fitzsimons, Peter Zweifel, R. Giusteri, Ph. Jetzer, M. Knopp, T. Ramsey, D. I. Robertson, J. Mehta, Domenico Giardini, W. J. Weber, M. Girard, Rita Dolesi, L. Martin-Polo, Colleen Marrese-Reading, Karsten Danzmann, D. Bame, I. Li, Eric Plagnol, B. Kaune, Víctor S. Martín, C. Valerio, Andrew Romero-Wolf, D. Nguyen, J. Baird, Greg M. Anderson, Michael Perreur-Lloyd, Peiman Maghami, Davor Mance, D. Texier, John Ziemer, J. Tallon, Antoine Petiteau, Paul McNamara, A. Ruiz, Carlos F. Sopuerta, J. O’Donnell, Daniele Vetrugno, Curt Cutler, J. Mennela, P. Pivato, Jurg Zwahlen, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), ST7, LISA Pathfinder, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and ST7 Team
Subjects: detector: technology, Space technology, Gravitational-wave observatory, Physics and Astronomy (miscellaneous), engineering, FOS: Physical sciences, Thrust, Astronomy & Astrophysics, 01 natural sciences, 7. Clean energy, Noise (electronics), Physics, Particles & Fields, cosmic rays, 0103 physical sciences, Experiments in gravity, thrust, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Aerospace engineering, noise: acceleration, 010306 general physics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), activity report, Physics, LISA, Science & Technology, Spacecraft, density: spectral, business.industry, Payload, Noise spectral density, Pathfinder, Physical Sciences, control system, business, Astrophysics - Instrumentation and Methods for Astrophysics, cosmology, performance
Abstract: The Space Technology 7 Disturbance Reduction System (ST7-DRS) is a NASA technology demonstration payload that operated from January 2016 through July of 2017 on the European Space Agency's LISA Pathfinder spacecraft. The joint goal of the NASA and ESA missions was to validate key technologies for a future space-based gravitational wave observatory targeting the source-rich milliHertz band. The two primary components of ST7-DRS are a micropropulsion system based on colloidal micro-Newton thrusters (CMNTs) and a control system that simultaneously controls the attitude and position of the spacecraft and the two free-flying test masses (TMs). This paper presents our main experimental results and summarizes the overall the performance of the CMNTs and control laws. We find that the CMNT performance to be consistent with pre-flight predictions, with a measured system thrust noise on the order of $100\,\textrm{nN}/\sqrt{\textrm{Hz}}$ in the $1\,\textrm{mHz}\leq f \leq 30\,\textrm{mHz}$ band. The control system maintained the TM-spacecraft separation with an RMS error of less than 2$\,$nm and a noise spectral density of less than $3\,\textrm{nm}/\sqrt{\textrm{Hz}}$ in the same band. Thruster calibration measurements yield thrust values consistent with the performance model and ground-based thrust-stand measurements, to within a few percent. We also report a differential acceleration noise between the two test masses with a spectral density of roughly $3\,\textrm{fm}/\textrm{s}^2/\sqrt{\textrm{Hz}}$ in the $1\,\textrm{mHz}\leq f \leq 30\,\textrm{mHz}$ band, slightly less than twice as large as the best performance reported with the baseline LISA Pathfinder configuration and below the current requirements for the Laser Interferometer Space Antenna (LISA) mission.
Published: 2018

21. Measuring the Galactic Cosmic Ray Flux with the LISA Pathfinder Radiation Monitor

Author: A. Cesarini, G. Russano, Ignacio Mateos, Ivan Lloro, Daniele Bortoluzzi, L. Mendes, Peter Zweifel, Gerhard Heinzel, Miquel Nofrarías, Domenico Giardini, J. P. López-Zaragoza, A. Wittchen, Ferran Gibert, M. de Deus Silva, F. Martin-Porqueras, J. Reiche, Peter Wass, A. M. Cruise, N. Finetti, Davor Mance, Mauro Hueller, B. Kaune, N. Korsakova, D. Texier, Lluis Gesa, T. J. Sumner, L. Liu, G. Dixon, Oliver Jennrich, Catia Grimani, E. Castelli, S. Vitale, Michele Armano, R. Maarschalkerweerd, Ph. Jetzer, Pierre Binétruy, M. Freschi, Antoine Petiteau, Paul McNamara, Luigi Ferraioli, D. I. Robertson, Jacob Slutsky, Valerio Ferroni, E. Plagnol, James Ira Thorpe, Carlos F. Sopuerta, D. Hoyland, Karsten Danzmann, M. Born, L. Martin-Polo, Antonella Cavalleri, J. Grzymisch, Henri Inchauspe, Ingo Diepholz, V. Martín, J. Martino, Daniele Vetrugno, Nikolaos Karnesis, H. Ward, F. Rivas, L. Wissel, P. Pivato, Gudrun Wanner, Juan Ramos-Castro, I. Harrison, Michael Perreur-Lloyd, N. Meshskar, Christian J. Killow, José F. F. Mendes, M. Hewitson, W. J. Weber, R. Giusteri, Rita Dolesi, J. Baird, E. D. Fitzsimons, J. A. Lobo, S. Paczkowski, Daniel Hollington, Heather Audley, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), AstroParticule et Cosmologie ( APC - UMR 7164 ), Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)
Subjects: Astrofísica, Pathfinder, Astrophysics::High Energy Astrophysical Phenomena, Flux, FOS: Physical sciences, Cosmic ray, Astrophysics, Radiation, 01 natural sciences, 0202 Atomic, Molecular, Nuclear, Particle And Plasma Physics, Charging, GCR, GEANT4, LISA, Radiation Monitor, Astronomy and Astrophysics, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], [ 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), Physics, Spacecraft, 010308 nuclear & particles physics, Gravitational wave, business.industry, Astronomy, Nuclear & Particles Physics, 0201 Astronomical And Space Sciences, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], Physics::Space Physics, Heliospheric current sheet, business, Astrophysics - Instrumentation and Methods for Astrophysics, Noise (radio), astro-ph.IM
Abstract: © . This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Test mass charging caused by cosmic rays will be a significant source of acceleration noise for space-based gravitational wave detectors like LISA. Operating between December 2015 and July 2017, the technology demonstration mission LISA Pathfinder included a bespoke monitor to help characterise the relationship between test mass charging and the local radiation environment. The radiation monitor made in situ measurements of the cosmic ray flux while also providing information about its energy spectrum. We describe the monitor and present measurements which show a gradual 40% increase in count rate coinciding with the declining phase of the solar cycle. Modulations of up to 10% were also observed with periods of 13 and 26 days that are associated with co-rotating interaction regions and heliospheric current sheet crossings. These variations in the flux above the monitor detection threshold (¿˜¿70¿MeV) are shown to be coherent with measurements made by the IREM monitor on-board the Earth orbiting INTEGRAL spacecraft. Finally we use the measured deposited energy spectra, in combination with a GEANT4 model, to estimate the galactic cosmic ray differential energy spectrum over the course of the mission.
Published: 2017

22. Messier 81's Planck view vs its halo mapping

Author: Asghar Qadir, Vahe Gurzadyan, G. Ingrosso, A. Amekhyan, Daniele Vetrugno, Ph. Jetzer, A. L. Kashin, G. Yegorian, A. A. Nucita, S. Sargsyan, F. De Paolis, Gurzadyan, V. G., De Paolis, F., Nucita, A. A., Kashin, A. L., Amekhyan, A., Sargsyan, S., Yegorian, G., Qadir, A., Ingrosso, G., Jetzer, Ph., and Vetrugno, D.
Subjects: media_common.quotation_subject, Cosmic microwave background, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Rotation, 01 natural sciences, Asymmetry, symbols.namesake, 0103 physical sciences, Planck, 010303 astronomy & astrophysics, Galactic Halos, Dark Matter, Astrophysics::Galaxy Astrophysics, media_common, Physics, Spiral galaxy, 010308 nuclear & particles physics, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), symbols, Intergalactic travel, Halo
Abstract: This paper is a follow-up of a previous paper about the M82 galaxy and its halo based on Planck observations. As in the case of M82, so also for the M81 galaxy a substantial North-South and East-West temperature asymmetry is found, extending up to galactocentric distances of about $1.5^\circ$. The temperature asymmetry is almost frequency independent and can be interpreted as a Doppler-induced effect related to the M81 halo rotation and/or triggered by the gravitational interaction of the galaxies within the M81 Group. Along with the analogous study of several nearby edge-on spiral galaxies, the CMB temperature asymmetry method thus is shown to act as a direct tool to map the galactic haloes and/or the intergalactic bridges, invisible in other bands or by other methods., 5 pages, 3 figures, in press in Astronomy and Astrophysics, Main Journal
Published: 2017

23. LISA Pathfinder closed-loop analysis: a model breakdown of the in-loop observables

Author: Ph. Jetzer, W. J. Weber, Lluis Gesa, Karsten Danzmann, Alexander Schleicher, F. Rivas, R. Maarschalkerweerd, A. Wittchen, J. Grzymisch, Antoine Petiteau, Paul McNamara, D. Wealthy, Gudrun Wanner, Juan Ramos-Castro, H. Rozemeijer, D. Shaul, H. Ward, Eric Plagnol, Catia Grimani, Ian Harrison, Henri Inchauspe, Ignacio Mateos, Carlos F. Sopuerta, Domenico Giardini, A. Zambotti, Michael Troebs, C. Zanoni, P. Prat, R. De Rosa, Michele Armano, B. Kaune, A. Lobo, S. Madden, Antonella Cavalleri, M. Freschi, C. Garcia Marrirodriga, N. Dunbar, M. de Deus Silva, R. Gerndt, J. Baird, M. Bassan, J. Martino, L. Mendel, Daniele Vetrugno, L. Wissel, Pierre Binétruy, L. Di Fiore, J. P. López-Zaragoza, J. Reiche, Martin Hewitson, E. D. Fitzsimons, Oliver Jennrich, Daniel Hollington, Víctor S. Martín, Daniele Bortoluzzi, A. Cesarini, Michael Perreur-Lloyd, G. Russano, Ferran Gibert, Tobias Ziegler, P. Pivato, Gerard Auger, R. Giusteri, M. Caleno, N. Korsakova, Ingo Diepholz, Miquel Nofrarías, Ivan Lloro, M. Cruise, D. I. Robertson, Peter Zweifel, M. Hueller, Luigi Ferraioli, Ruggero Stanga, Tamara Sumner, R. Flatscher, Aniello Grado, Heather Audley, U. Ragnit, N. Karnesis, Rita Dolesi, José F. F. Mendes, Davor Mance, B. Johlander, D. Texier, Jacob Slutsky, Valerio Ferroni, M. Born, D. Hoyland, Peter Wass, James Ira Thorpe, L. Martin-Polo, F. Martin-Porqueras, C. Trenke, S. Paczkowski, P. Sarra, S. Vitale, N. Brandt, L. Liu, Christian J. Killow, Gerhard Heinzel, and LISA Pathfinder Collaboration
Subjects: Physics, History, Science & Technology, 02 Physical Sciences, Observable, Astronomy & Astrophysics, 01 natural sciences, 09 Engineering, Computer Science Applications, Education, Loop (topology), Pathfinder, Control theory, 0103 physical sciences, Physical Sciences, 010306 general physics, Closed loop analysis
Abstract: This paper describes a methodology to analyze, in the frequency domain, the steady-state control performances of the LISA Pathfinder mission. In particular, it provides a technical framework to give a comprehensive understanding of the spectra of all the degrees of freedom by breaking them down into their various physical origins, hence bringing out the major contributions of the control residuals. A reconstruction of the measured in-loop output, extracted from a model of the closed-loop system, is shown as an instance to illustrate the potential of such a model breakdown of the data.
Published: 2017

24. LISA Pathfinder: First steps to observing gravitational waves from space

Author: N. Karnesis, C. Garca Marrirodriga, Michele Armano, Ian Harrison, Jacob Slutsky, Valerio Ferroni, D. Hoyland, M. Freschi, Henri Inchauspe, M. Cruise, Daniele Vetrugno, Michael Perreur-Lloyd, Gerhard Heinzel, F. Rivas, Lluis Gesa, Ignacio Mateos, P. Pivato, Ph. Jetzer, Gudrun Wanner, Juan Ramos-Castro, R. Maarschalkerweerd, A. Wittchen, R. Gerndt, Peter Wass, Karsten Danzmann, Antoine Petiteau, Paul McNamara, S. Paczkowski, L. Liu, Carlos F. Sopuerta, R. Giusteri, P. Prat, N. Dunbar, Antonella Cavalleri, S. Vitale, L. Martin-Polo, J. Baird, U. Ragnit, Christian J. Killow, Domenico Giardini, M. de Deus Silva, Rita Dolesi, P. Sarra, H. Rozemeijer, Tobias Ziegler, R. De Rosa, J. Reiche, A. Zambotti, W. J. Weber, D. Shaul, A. Cesarini, G. Russano, M. Bassan, M. Hueller, J. Martino, E. D. Fitzsimons, Alexander Schleicher, R. Flatscher, Catia Grimani, F. Martin-Porqueras, Michael Troebs, Peter Zweifel, J. Grzymisch, M. Born, N. Korsakova, Aniello Grado, Heather Audley, H. Ward, Pierre Binétruy, James Ira Thorpe, L. Wissel, Daniele Bortoluzzi, L. Mendes, B. Johlander, Miquel Nofrarías, C. Zanoni, Eric Plagnol, Ruggero Stanga, Ingo Diepholz, A. Lobo, Martin Hewitson, Daniel Hollington, L. Di Fiore, Oliver Jennrich, M. Caleno, D. Wealthy, D. I. Robertson, C. Trenkel, Luigi Ferraioli, Tamara Sumner, Davor Mance, D. Texier, B. Kaune, S. Madden, Ivan Lloro, José F. F. Mendes, Víctor S. Martín, N. Brandt, J. P. López-Zaragoza, Ferran Gibert, Gerard Auger, and LISA Pathfinder Collaboration
Subjects: Physics, History, Science & Technology, 02 Physical Sciences, Gravitational wave, Settore FIS/01 - Fisica Sperimentale, Astronomy, Astronomy & Astrophysics, Space (mathematics), 09 Engineering, Computer Science Applications, Education, Pathfinder, Physical Sciences
Abstract: LISA Pathfinder, the European Space Agency's technology demonstrator mission for future spaceborne gravitational wave observatories, was launched on 3 December 2015, from the European space port of Kourou, French Guiana. After a short duration transfer to the final science orbit, the mission has been gathering science data since. This data has allowed the science community to validate the critical technologies and measurement principle for low frequency gravitational wave detection and thereby confirming the readiness to start the next generation gravitational wave observatories, such as LISA. This paper will briefly describe the mission, followed by a description of the science operations highlighting the performance achieved. Details of the various experiments performed during the nominal science operations phase can be found in accompanying papers in this volume.
Published: 2017

25. Charge-induced force noise on free-falling test masses: results from LISA Pathfinder

Author: B. Johlander, Heather Audley, Gerhard Heinzel, M. Cruise, Ph. Jetzer, José F. F. Mendes, R. Giusteri, M. Hewitson, Lluis Gesa, G. Auger, Antoine Petiteau, Jacob Slutsky, Valerio Ferroni, Paul McNamara, R. Gerndt, Rita Dolesi, N. Korsakova, R. Maarschalkerweerd, A. Wittchen, Karsten Danzmann, Michele Armano, J. Baird, Carlos F. Sopuerta, S. Paczkowski, M. Freschi, Oliver Jennrich, P. Prat, E. D. Fitzsimons, Henri Inchauspe, Daniele Vetrugno, W. J. Weber, Christian J. Killow, B. Kaune, P. Sarra, S. Madden, Daniele Bortoluzzi, Peter Wass, L. Mendes, A. Bursi, C. García Marirrodriga, P. Pivato, Miquel Nofrarías, J. Huesler, F. Martin-Porqueras, Mauro Hueller, H. Rozemeijer, Antonella Cavalleri, R. Flatscher, Pierre Binétruy, N. Brandt, Nikolaos Karnesis, C. Trenkel, C. Zanoni, J. Martino, S. Vitale, Ignacio Mateos, A. Schleicher, J. Gallegos, Daniel Hollington, T. J. Sumner, L. Liu, J. P. López-Zaragoza, Ferran Gibert, M. de Deus Silva, Luigi Ferraioli, N. Dunbar, Catia Grimani, Domenico Giardini, J. A. Romera Perez, Eric Plagnol, V. Martín, M. Caleno, D. I. Robertson, Tobias Ziegler, James Ira Thorpe, A. Moroni, D. Wealthy, U. Ragnit, Ivan Lloro, Davor Mance, D. Texier, J. Reiche, A. Cesarini, G. Russano, Peter Zweifel, I. Harrison, L. Martin-Polo, Michael Perreur-Lloyd, J. Grzymisch, H. Ward, M. Born, Ingo Diepholz, F. Rivas, Gudrun Wanner, Juan Ramos-Castro, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), LISA Pathfinder, LISA Pathfinder Collaboration, Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), AstroParticule et Cosmologie ( APC - UMR 7164 ), and Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA )
Subjects: Gravitational-wave observatory, Capacitive sensing, General Physics and Astronomy, Interplanetary flight, Astrophysics, 01 natural sciences, 09 Engineering, Laser interferometers, Gravitational wave detectors, Cosmic ray measurement, Dedicated measurements, force: electrostatic, [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], MISSION, Physics, 02 Physical Sciences, Stochastic systems, Astrophysics::Instrumentation and Methods for Astrophysics, Interferometria làser, Electrostatics, Cosmology, electric field, observatory, cosmic radiation, frequency, Physical Sciences, Electrostàtica, Astrophysics - Instrumentation and Methods for Astrophysics, European Space Agency, electrostatic, Noise (radio), Gravitation, Laser interferometer space antenna, General Physics, Electric fields, Physics, Multidisciplinary, Capacitive sensors, FOS: Physical sciences, Gravity waves, LISA Pathfinder Collaboration, Electrostatic measurements, Gravitational waves, Physics and Astronomy (all), Acceleration, Ones gravitacionals, Gravitational reference sensors, Electric field, 0103 physical sciences, Frequency bands, stochastic, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], noise: acceleration, coupling, 010306 general physics, Electrostatic modeling, Instrumentation and Methods for Astrophysics (astro-ph.IM), 01 Mathematical Sciences, LISA, Science & Technology, Interferometers, 010308 nuclear & particles physics, Gravitational wave, Electrostatic force, FIELDS, gravitational radiation detector, Computational physics, Pathfinder, gravitation, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], mass, Laser interferometry, Differential accelerations, SYSTEM, astro-ph.IM
Abstract: We report on electrostatic measurements made on board the European Space Agency mission LISA Pathfinder. Detailed measurements of the charge-induced electrostatic forces exerted on free-falling test masses (TMs) inside the capacitive gravitational reference sensor are the first made in a relevant environment for a space-based gravitational wave detector. Employing a combination of charge control and electric-field compensation, we show that the level of charge-induced acceleration noise on a single TM can be maintained at a level close to 1.0 fm/s^2/sqrt(Hz) across the 0.1-100 mHz frequency band that is crucial to an observatory such as LISA. Using dedicated measurements that detect these effects in the differential acceleration between the two test masses, we resolve the stochastic nature of the TM charge build up due to interplanetary cosmic rays and the TM charge-to-force coupling through stray electric fields in the sensor. All our measurements are in good agreement with predictions based on a relatively simple electrostatic model of the LISA Pathfinder instrument., Comment: 9 Pages, 3 figures
Published: 2017

26. Laser Frequency Noise Stabilisation and Interferometer Path Length Differences on LISA Pathfinder

Author: Daniele Vetrugno, Antonella Cavalleri, and LISA Pathfinder Collaboration
Subjects: Physics, Coupling, History, Gravitational-wave observatory, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Phase (waves), Computer Science Applications, Education, Interferometry, Optics, Pathfinder, Path length, Astronomical interferometer, business, Noise (radio)
Abstract: The LISA Pathfinder mission is a technology demonstrator for a LISA-like gravitational wave observatory in space. Its first results already exceed the expectations. This is also true for the optical metrology system which measures the distance in between the two free-floating test masses with unpreceded precision. One noise source that can possibly affect the measurement is the laser frequency noise. It is measured with a dedicated interferometer and suppressed with a control loop. We measured the laser frequency noise and characterised the control loop in flight. The coupling of laser frequency noise into the measured phase is directly proportional to the path length difference in the respective interferometer. Dedicated experiments have been performed to estimate the path length difference in flight. In addition, this frequency stabilisation scheme is also a possible solution for the LISA mission.
Published: 2017

27. Preliminary results on the suppression of sensing cross-talk in LISA Pathfinder

Author: Daniele Vetrugno, Antonella Cavalleri, Nikolaos Karnesis, and LISA Pathfinder collaboration
Subjects: Spacecraft motion, History, Noise suppression, Preliminary analysis, LISA Pathfinder, Radio spectrum, Education, Crosstalk, Optics, Chemical reactions, Electronic engineering, Frequency bands, ddc:530, Crosstalk noise, Konferenzschrift, Physics, business.industry, Computer Science Applications, Pathfinder, Cross-couplings, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, business, Space probes
Abstract: In the original paper describing the first measurements performed with LISA Pathfinder, a bulge in the acceleration noise was shown in the 200 mHz - 20 mHz frequency band. This bulge noise originated from cross-coupling of spacecraft motion into the longitudinal readout and it was shown that it is possible to subtract this cross-talk noise. We discuss here the model that was used for subtraction as well as an alternative approach to suppress the cross talk by realignment of the test masses. Such a realignment was performed after preliminary analysis of a dedicated cross-talk experiment, and we show the resulting noise suppression. Since then, further experiments have been performed to investigate the cross-coupling behaviour, however analysis of these experiments is still on-going. © Published under licence by IOP Publishing Ltd. ESA/22331/09/NL/HB ESA/16238/10/NL/HB DLR/FKZ/OQ 0501 DLR/FKZ/50 OQ 1601 DFG/EXC/QUEST
Published: 2017

28. LISA Pathfinder: OPD loop characterisation

Author: Daniele Vetrugno, Antonella Cavalleri, and LISA Pathfinder collaboration
Subjects: Phase difference, Physics, History, business.industry, Computer Science Applications, Education, Loop (topology), Pathfinder, Optics, Control system, Astronomical interferometer, business, Optical metrology, Heterodyne interferometer
Published: 2017

29. LISA Pathfinder: Optical Metrology System monitoring during operations

Author: Daniele Vetrugno, Antonella Cavalleri, and LISA Pathfinder collaboration
Subjects: Physics, History, Laser interferometer space antenna, System monitoring, Computer Science Applications, Education, Units of measurement, Pathfinder, Astronomical interferometer, Systems engineering, Satellite, Duration (project management), Optical metrology, Remote sensing
Abstract: The LISA Pathfinder (LPF) mission has demonstrated excellent performance. In addition to having surpassed the main mission goals, data has been collected from the various subsystems throughout the duration of the mission. This data is a valuable resource, both for a more complete understanding of the LPF satellite and the differential acceleration measurements, as well as for the design of the future Laser Interferometer Space Antenna (LISA) mission. Initial analysis of the Optical Metrology System (OMS) data was performed as part of daily system monitoring, and more in-depth analyses are ongoing. This contribution presents an overview of these activities along with an introduction to the OMS.
Published: 2017

30. Coupling of relative intensity noise and pathlength noise to the length measurement in the optical metrology system of LISA Pathfinder

Author: Daniele Vetrugno, Antonella Cavalleri, Andreas Wittchen, and LISA Pathfinder Collaboration
Subjects: Heterodyne, Physics, History, Gravitational-wave observatory, Relative intensity noise, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Phase (waves), Signal, Computer Science Applications, Education, Interferometry, Optics, Path length, business, Noise (radio)
Abstract: LISA Pathfinder is a technology demonstration mission for the space-based gravitational wave observatory, LISA. It demonstrated that the performance requirements for the interferometric measurement of two test masses in free fall can be met. An important part of the data analysis is to identify the limiting noise sources. [1] This measurement is performed with heterodyne interferometry. The performance of this optical metrology system (OMS) at high frequencies is limited by sensing noise. One such noise source is Relative Intensity Noise (RIN). RIN is a property of the laser, and the photodiode current generated by the interferometer signal contains frequency dependant RIN. From this electric signal the phasemeter calculates the phase change and laser power, and the coupling of RIN into the measurement signal depends on the noise frequency. RIN at DC, at the heterodyne frequency and at two times the heterodyne frequency couples into the phase. Another important noise at high frequencies is path length noise. To reduce the impact this noise is suppressed with a control loop. Path length noise not suppressed will couple directly into the length measurement. The subtraction techniques of both noise sources depend on the phase difference between the reference signal and the measurement signal, and thus on the test mass position. During normal operations we position the test mass at the interferometric zero, which is optimal for noise subtraction purposes. This paper will show results from an in-flight experiment where the test mass position was changed to make the position dependant noise visible.
Published: 2017

31. Calibrating LISA Pathfinder raw data into femto-g differential accelerometry

Author: Daniele Vetrugno, Antonella Cavalleri, Nikolaos Karnesis, and LISA Pathfinder Collaboration
Subjects: History, Calibration experiments, Spacecraft motion, Femto, Accelerometer, Residual, LISA Pathfinder, Education, Acceleration, Accelerometry, Calibration, ddc:530, Konferenzschrift, Remote sensing, Physics, Spacecraft, business.industry, Geodesy, In-flight tests, Computer Science Applications, Noise, Pathfinder, Noise levels, Differential accelerations, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, business, Local source, Space probes
Abstract: LISA Pathfinder is an in-flight test of the local sources of acceleration noise in LISA. The acceleration noise level in LISA Pathfinder is measured by the residual differential acceleration Δg between the two test masses once the coupling to the spacecraft motion has been removed. The full process from raw data to Δg passes through a series of calibration experiments and different data elaboration procedure which are thoroughly used during the mission and represent the baseline for any other further investigation. © Published under licence by IOP Publishing Ltd.
Published: 2017
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32. LISA Pathfinder: Understanding DWS noise performance for the LISA mission

Author: Daniele Vetrugno, Antonella Cavalleri, and LPF collaboration
Subjects: Physics, History, Noise, Pathfinder, Acoustics, Rotation (mathematics), Computer Science Applications, Education
Published: 2017

33. Planck confirmation of the disk and halo rotation of M 31

Author: Daniele Vetrugno, Vahe Gurzadyan, Asghar Qadir, H. G. Khachatryan, S. Mirzoyan, A. A. Nucita, F. De Paolis, A. L. Kashin, Ph. Jetzer, G. Ingrosso, E. Poghosian, DE PAOLIS, Francesco, V. G., Gurzadyan, Nucita, Achille, Ingrosso, Gabriele, A. L., Kashin, H. G., Khachatryan, S., Mirzoyan, E., Poghosian, Jetzer, P. h., A., Qadir, and Vetrugno, Daniele
Subjects: Physics, 010308 nuclear & particles physics, media_common.quotation_subject, Cosmic microwave background, Local Group, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Rotation, 01 natural sciences, Asymmetry, CMB cold spot, Galaxy, symbols.namesake, Space and Planetary Science, 0103 physical sciences, symbols, Galactic halos, Halo, Planck, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common
Abstract: Planck data acquired during the first 15.4 months of observations toward both the disk and halo of the M 31 galaxy were analyzed. We confirm the temperature asymmetry that was previously detected by using the seven-year WMAP data in the direction of the rotation of M 31, which indicates that this is a Doppler-induced effect. The asymmetry extends to about 10° (≃130 kpc) from the center of M 31. We also investigated the recent problem raised in Rubin and Loeb (2014, JCAP, 01, 051) about the kinetic Sunyaev-Zel’dovich effect from the diffuse hot gas in the Local Group, which is predicted to generate a hot spot of a few degrees in size in the cosmic microwave background maps in the direction of M 31, where the free electron optical depth is highest. We also considered whether the same effect in the opposite direction with respect to the M 31 galaxy induces a minimum in temperature in the Planck maps of the sky. We find that the Planck data at 100 GHz show an even stronger effect than that expected.
Published: 2014
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34. Triangulum galaxy viewed by Planck

Author: F. De Paolis, L. Chemin, G. Yegorian, Ph. Jetzer, H. G. Khachatryan, Asghar Qadir, G. Ingrosso, Daniele Vetrugno, A. L. Kashin, Vahe Gurzadyan, A. A. Nucita, S. Sargsyan, M2A 2016, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche en Communications et en Cybernétique de Nantes (IRCCyN), Mines Nantes (Mines Nantes)-École Centrale de Nantes (ECN)-Ecole Polytechnique de l'Université de Nantes (EPUN), Université de Nantes (UN)-Université de Nantes (UN)-PRES Université Nantes Angers Le Mans (UNAM)-Centre National de la Recherche Scientifique (CNRS), Istituto Nazionale di Geofisica e di Oceanografia Sperimentale (OGS), Physik-Institut [Zürich], Universität Zürich [Zürich] = University of Zurich (UZH), DE PAOLIS, Francesco, Gurzadyan, V. G., Nucita, Achille, Chemin, L., Qadir, A., Kashin, A. L. ., Khachatryan, H. G., Sargsyan, S., Yegorian, G., Ingrosso, Gabriele, Jetzer, P. h., and Vetrugno, D.
Subjects: media_common.quotation_subject, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Asymmetry, symbols.namesake, 0103 physical sciences, Differential rotation, Planck, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common, Physics, Triangulum, 010308 nuclear & particles physics, galaxie, Astronomy and Astrophysics, cmb, Astrophysics - Astrophysics of Galaxies, Galaxy, triangulum galaxy, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Baryon, Space and Planetary Science, Sky, Astrophysics of Galaxies (astro-ph.GA), symbols, Halo
Abstract: We used Planck data to study the M33 galaxy and find a substantial temperature asymmetry with respect to its minor axis projected onto the sky plane. This temperature asymmetry correlates well with the HI velocity field at 21 cm, at least within a galactocentric distance of 0.5 degree, and it is found to extend up to about 3 degrees from the galaxy center. We conclude that the revealed effect, that is, the temperature asymmetry and its extension, implies that we detected the differential rotation of the M33 galaxy and of its extended baryonic halo., 8 pages, 8 figures, in press on Astronomy and Astrophysics, main journal
Published: 2016

35. Optimal design of calibration signals in space-borne gravitational wave detectors

Author: Miquel Nofrarias, Nikolaos Karnesis, Ferran Gibert, Michele Armano, Heather Audley, Karsten Danzmann, Ingo Diepholz, Rita Dolesi, Luigi Ferraioli, Valerio Ferroni, Martin Hewitson, Mauro Hueller, Henri Inchauspe, Oliver Jennrich, Natalia Korsakova, Paul W. McNamara, Eric Plagnol, James I. Thorpe, Daniele Vetrugno, Stefano Vitale, Peter Wass, William J. Weber, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie ( APC - UMR 7164 ), and Centre National de la Recherche Scientifique ( CNRS ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA )
Subjects: Optimal design, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), 01 natural sciences, General Relativity and Quantum Cosmology, [ PHYS.GRQC ] Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Theoretical physics, 0103 physical sciences, Electronic engineering, Calibration, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Sensitivity (control systems), 010306 general physics, [ PHYS.PHYS.PHYS-INS-DET ] Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Instrumentation and Methods for Astrophysics (astro-ph.IM), Physics, LISA, gravitational radiation detector: sensitivity, 010308 nuclear & particles physics, Estimation theory, Gravitational wave, Design of experiments, Detector, gravitational radiation, Astrophysics::Instrumentation and Methods for Astrophysics, gravitational radiation detector, Pathfinder, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Astrophysics - Instrumentation and Methods for Astrophysics, gravitational radiation detector: calibration
Abstract: Future space borne gravitational wave detectors will require a precise definition of calibration signals to ensure the achievement of their design sensitivity. The careful design of the test signals plays a key role in the correct understanding and characterisation of these instruments. In that sense, methods achieving optimal experiment designs must be considered as complementary to the parameter estimation methods being used to determine the parameters describing the system. The relevance of experiment design is particularly significant for the LISA Pathfinder mission, which will spend most of its operation time performing experiments to characterise key technologies for future space borne gravitational wave observatories. Here we propose a framework to derive the optimal signals ---in terms of minimum parameter uncertainty--- to be injected to these instruments during its calibration phase. We compare our results with an alternative numerical algorithm which achieves an optimal input signal by iteratively improving an initial guess. We show agreement of both approaches when applied to the LISA Pathfinder case., 12 pages, 6 figures
Published: 2016

36. Sub-Femto- g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results

Author: R. Gerndt, F. Rivas, Daniele Bortoluzzi, L. Carbone, L. Mendes, Ph. Jetzer, Walter Fichter, Jacob Slutsky, Valerio Ferroni, D. Hoyland, Ulrich Johann, Gudrun Wanner, Miquel Nofrarías, Peter Wass, Juan Ramos-Castro, Pierre Binétruy, Ivan Lloro, Lluis Gesa, G. Auger, C. Trenkel, Stefano Vitale, James Ira Thorpe, Antoine Petiteau, A. Grynagier, Paul McNamara, A. F. García Marín, G. Congedo, Luigi Ferraioli, M. Born, R. Maarschalkerweerd, Karsten Danzmann, V Wand, C. Zanoni, A. Monsky, Ruggero Stanga, Ingo Diepholz, Carlos F. Sopuerta, F. Steier, A. Cesarini, José F. F. Mendes, Tobias Ziegler, N. Korsakova, G. Russano, F. Guzmán, H. Rozemeijer, M. Hewitson, A. Schleicher, B. Johlander, J. P. López-Zaragoza, Michael Perreur-Lloyd, Michele Armano, Daniel Hollington, Daniele Vetrugno, D. Wealthy, B. Kaune, S. Madden, P. Sarra, A. Zambotti, M. Diaz-Aguilo, Christian J. Killow, Peter Zweifel, Davor Mance, D. Shaul, T. J. Sumner, L. Liu, J. Grzymisch, H. Ward, M. Freschi, L. Di Fiore, Oliver Jennrich, Michael Tröbs, H. B. Tu, R. Flatscher, M. Caleno, D. I. Robertson, J. A. Lobo, S. Paczkowski, Ferran Gibert, L. Martin-Polo, P. Prat, I. Harrison, P. Pivato, Ignacio Mateos, C. García Marirrodriga, Mauro Hueller, D. Texier, A. Wittchen, U. Ragnit, Aniello Grado, Heather Audley, J Sanjuán, C. Warren, J. Reiche, B. Rais, Henri Inchauspe, G. Dixon, Eric Plagnol, V. Martín, Domenico Giardini, Daniele Nicolodi, N. Brandt, Nikolaos Karnesis, Giacomo Ciani, Antonella Cavalleri, J. Martino, R. Giusteri, L. Wissel, Rita Dolesi, J. Baird, Massimo Bassan, R. De Rosa, E. D. Fitzsimons, Gerhard Heinzel, W. J. Weber, A. M. Cruise, F. Martin-Porqueras, M. de Deus Silva, N. Dunbar, Catia Grimani, AstroParticule et Cosmologie (APC (UMR_7164)), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Universitat Politècnica de Catalunya. Departament d'Enginyeria Electrònica, UK Space Agency, Science and Technology Facilities Council (STFC), Armano, M., Audley, H., Auger, G., Baird, J. T., Bassan, M., Binetruy, P., Born, M., Bortoluzzi, D., Brandt, N., Caleno, M., Carbone, L., Cavalleri, A., Cesarini, A., Ciani, G., Congedo, G., Cruise, A. M., Danzmann, K., De Deus Silva, M., DE ROSA, Rosario, Diaz Aguiló, M., Di Fiore, L., Diepholz, I., Dixon, G., Dolesi, R., Dunbar, N., Ferraioli, L., Ferroni, V., Fichter, W., Fitzsimons, E. D., Flatscher, R., Freschi, M., García Marín, A. F., García Marirrodriga, C., Gerndt, R., Gesa, L., Gibert, F., Giardini, D., Giusteri, R., Guzmán, F., Grado, A., Grimani, C., Grynagier, A., Grzymisch, J., Harrison, I., Heinzel, G., Hewitson, M., Hollington, D., Hoyland, D., Hueller, M., Inchauspé, H., Jennrich, O., Jetzer, P., Johann, U., Johlander, B., Karnesis, N., Kaune, B., Korsakova, N., Killow, C. J., Lobo, J. A., Lloro, I., Liu, L., López Zaragoza, J. P., Maarschalkerweerd, R., Mance, D., Martín, V., Martin Polo, L., Martino, J., Martin Porqueras, F., Madden, S., Mateos, I., Mcnamara, P. W., Mendes, J., Mendes, L., Monsky, A., Nicolodi, D., Nofrarias, M., Paczkowski, S., Perreur Lloyd, M., Petiteau, A., Pivato, P., Plagnol, E., Prat, P., Ragnit, U., Raïs, B., Ramos Castro, J., Reiche, J., Robertson, D. I., Rozemeijer, H., Rivas, F., Russano, G., Sanjuán, J., Sarra, P., Schleicher, A., Shaul, D., Slutsky, J., Sopuerta, C. F., Stanga, R., Steier, F., Sumner, T., Texier, D., Thorpe, J. I., Trenkel, C., Tröbs, M., Tu, H. B., Vetrugno, D., Vitale, S., Wand, V., Wanner, G., Ward, H., Warren, C., Wass, P. J., Wealthy, D., Weber, W. J., Wissel, L., Wittchen, A., Zambotti, A., Zanoni, C., Ziegler, T., Zweifel, P., Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)
Subjects: General Physics, Gravitational-wave observatory, detector: performance, Physics, Multidisciplinary, General Physics and Astronomy, Astrophysics, 01 natural sciences, 7. Clean energy, Noise (electronics), 09 Engineering, LISA Pathfinder, Gravitational waves, Acceleration, Physics and Astronomy (all), Square root, Ones gravitacionals, gas, 0103 physical sciences, Orders of magnitude (speed), interferometer: satellite, noise: acceleration, 010303 astronomy & astrophysics, 01 Mathematical Sciences, MISSION, Physics, LISA, Science & Technology, 02 Physical Sciences, density: spectral, 010308 nuclear & particles physics, Gravitational wave, Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, gravitational radiation, Spectral density, gravitational radiation detector: satellite, detector: sensitivity, gravitation, Physical Sciences, viscosity, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Brownian noise, readout, INTERFEROMETER
Abstract: We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 +/- 0.1 fm s(exp -2)/square root of Hz, or (0.54 +/- 0.01) x 10(exp -15) g/square root of Hz, with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 +/- 0.3) fm square root of Hz, about 2 orders of magnitude better than requirements. At f less than or equal to 0.5 mHz we observe a low-frequency tail that stays below 12 fm s(exp -2)/square root of Hz down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.
Published: 2016

37. Measuring fN force variations in the presence of constant nN forces: a torsion pendulum ground test of the LISA Pathfinder free-fall mode

Author: H. B. Tu, Daniele Vetrugno, S. Vitale, P. Pivato, R. Giusteri, M. Hueller, Rita Dolesi, Antonella Cavalleri, Valerio Ferroni, Ferran Gibert, W. J. Weber, A. Cesarini, G. Russano, and L. Liu
Subjects: Physics, Pathfinder, 010504 meteorology & atmospheric sciences, Physics and Astronomy (miscellaneous), Torsion pendulum clock, 0103 physical sciences, Mode (statistics), Mechanics, 010306 general physics, Constant (mathematics), 01 natural sciences, 0105 earth and related environmental sciences
Published: 2018

38. THE HIGH ENERGY VIEW OF THE GLOBULAR CLUSTER NGC 6388: IS AN INTERMEDIATE MASS BLACK HOLE OUT THERE?

Author: A. A. Nucita, Daniele Vetrugno, A. M. Read, G. Ingrosso, L. Manni, R. Saxton, and F. de Paolis
Subjects: Physics, High energy, Supermassive black hole, Intermediate-mass black hole, Globular cluster, Astronomy, Astrophysics
Published: 2015

39. POSSIBLE EVIDENCE OF THE M31 HALO ROTATION IN WMAP DATA

Author: Daniele Vetrugno, G. Ingrosso, Harutyun Khachatryan, Francesco De Paolis, S. Mirzoyan, Alexander Kashin, A. A. Nucita, Vahe Gurzadyan, Philippe Jetzer, and Asghar Qadir
Subjects: Physics, Astrophysics, Halo, Rotation, CMB cold spot
Published: 2015

40. Free-flight experiments in LISA Pathfinder

Author: C. Trenkel, F. Martin-Porqueras, J. Baird, Nikolaos Karnesis, Lluis Gesa, R. Gerndt, Paul McNamara, A. Bursi, A. Moroni, G. Auger, Curt Cutler, Karsten Danzmann, James Ira Thorpe, Valerio Ferroni, Gerhard Heinzel, C. Zanoni, Ian Harrison, R. Maarschalkerweerd, B. Johlander, Carlos F. Sopuerta, Michael Perreur-Lloyd, Rita Dolesi, R. Giusteri, M. Born, A. Schleicher, Daniele Vetrugno, N. Dunbar, P. Sarra, Luis Mendes, Peter Wass, Daniel Hollington, T. J. Sumner, Eric Plagnol, C. García Marirrodriga, B. Kaune, A. Wittchen, H. Rozemeijer, U. Ragnit, N. Brandt, H. Ward, S. Madden, D. Wealthy, Ingo Diepholz, P. Prat, P. Pivato, Mauro Hueller, H. B. Tu, Víctor S. Martín, Ewan Fitzsimons, Antonella Cavalleri, S. Paczkowski, Jacob Slutsky, M. Cruise, Michele Armano, Pierre Binetruy, J. A. Romera Perez, Davor Mance, José F. F. Mendes, Gudrun Wanner, Stefano Vitale, Juan Ramos-Castro, Philippe Jetzer, W. J. Weber, M. Freschi, Ivan Lloro, D. Texier, Domenico Giardini, S. Waschke, Antoine Petiteau, J. Huesler, J. Reiche, Oliver Jennrich, A. Cesarini, G. Russano, Tobias Ziegler, N. Korsakova, Peter Zweifel, H. Inchauspe, Catia Grimani, P. Maghami, Heather Audley, S. Wen, M. Caleno, D. I. Robertson, Christian J. Killow, Martin Hewitson, Luigi Ferraioli, Ignacio Mateos, Daniele Bortoluzzi, Miquel Nofrarías, J. Gallegos, and Ferran Gibert
Subjects: History, Inertial frame of reference, Testing, Orbits, General Relativity and Quantum Cosmology, LISA Pathfinder, Gravitational wave detectors, Primary (astronomy), Free flight, Spacecraft, Dewey Decimal Classification::500 | Naturwissenschaften, Physics, Noise source, Astrophysics::Instrumentation and Methods for Astrophysics, Flight experiments, Computer Science Applications, Drag, Tracking (position), Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, ddc:500, Astrophysics - Instrumentation and Methods for Astrophysics, Space probes, realizations, Gravitation, spaced data, On-orbit performance, spectral-analysis, FOS: Physical sciences, General Relativity and Quantum Cosmology (gr-qc), Gravity waves, Education, Acceleration, Space-based, Mission requirements, ddc:530, Aerospace engineering, Instrumentation and Methods for Astrophysics (astro-ph.IM), Konferenzschrift, algorithm, business.industry, Gravitational wave, Noise, Pathfinder, Potential sources, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, business
Abstract: The LISA Pathfinder mission will demonstrate the technology of drag-free test masses for use as inertial references in future space-based gravitational wave detectors. To accomplish this, the Pathfinder spacecraft will perform drag-free flight about a test mass while measuring the acceleration of this primary test mass relative to a second reference test mass. Because the reference test mass is contained within the same spacecraft, it is necessary to apply forces on it to maintain its position and attitude relative to the spacecraft. These forces are a potential source of acceleration noise in the LISA Pathfinder system that are not present in the full LISA configuration. While LISA Pathfinder has been designed to meet it's primary mission requirements in the presence of this noise, recent estimates suggest that the on-orbit performance may be limited by this `suspension noise'. The drift-mode or free-flight experiments provide an opportunity to mitigate this noise source and further characterize the underlying disturbances that are of interest to the designers of LISA-like instruments. This article provides a high-level overview of these experiments and the methods under development to analyze the resulting data., 13 pages, 5 figures. Accepted to Journal Of Physics, Conference Series. Presented at 10th International LISA Symposium, May 2014, Gainesville, FL, USA
Published: 2015
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41. In-flight thermal experiments for LISA Pathfinder: Simulating temperature noise at the Inertial Sensors

Author: Ivan Lloro, Antoine Petiteau, Paul McNamara, J. Huesler, C. Zanoni, M. Cruise, Stefano Vitale, Martin Hewitson, Carlos F. Sopuerta, Gerhard Heinzel, Daniel Hollington, S. Paczkowski, N. Brandt, Nikolaos Karnesis, Daniele Bortoluzzi, Daniele Vetrugno, L. Mendes, Ignacio Mateos, H. B. Tu, H. Ward, G. Auger, Miquel Nofrarías, P. Pivato, S. Wen, Tobias Ziegler, P. Sarra, A. Schleicher, A. Bursi, Antonella Cavalleri, S. Waschke, Michele Armano, F. Martin-Porqueras, Oliver Jennrich, Christian J. Killow, R. Maarschalkerweerd, D. Wealthy, A. Wittchen, M. Freschi, J. A. Perez Romera, P. Prat, C. García Marirrodriga, Heather Audley, H. Rozemeijer, Michael Perreur-Lloyd, Ewan Fitzsimons, Ingo Diepholz, Mauro Hueller, Peter Wass, Pierre Binétruy, M. Born, C. Trenkel, M. Caleno, B. Johlander, James Ira Thorpe, A. Moroni, D. I. Robertson, Gudrun Wanner, Juan Ramos-Castro, José F. F. Mendes, Eric Plagnol, V. Martín, Domenico Giardini, N. Dunbar, Catia Grimani, P. Maghami, R. Giusteri, R. Gerndt, Rita Dolesi, Ph. Jetzer, Karsten Danzmann, B. Kaune, S. Madden, Henri Inchauspe, I. Harrison, Davor Mance, D. Texier, J. Gallegos, Ferran Gibert, Luigi Ferraioli, Tamara Sumner, L. l. Gesa, J. Reiche, A. Cesarini, G. Russano, Jacob Slutsky, Valerio Ferroni, Peter Zweifel, U. Ragnit, W. J. Weber, J. Baird, and N. Korsakova
Subjects: History, Astronomy & Astrophysics, Noise (electronics), Education, Physics, Applied, Inertial measurement unit, ddc:530, Aerospace engineering, Konferenzschrift, Dewey Decimal Classification::500 | Naturwissenschaften, Physics, Spacecraft, Gravitational wave, business.industry, Detector, Electrical engineering, Computer Science Applications, Pathfinder, Physics::Space Physics, Measuring instrument, Brownian noise, ddc:500, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, business
Abstract: Thermal Diagnostics experiments to be carried out on board LISA Pathfinder (LPF) will yield a detailed characterisation of how temperature fluctuations affect the LTP (LISA Technology Package) instrument performance, a crucial information for future space based gravitational wave detectors as the proposed eLISA. Amongst them, the study of temperature gradient fluctuations around the test masses of the Inertial Sensors will provide as well information regarding the contribution of the Brownian noise, which is expected to limit the LTP sensitivity at frequencies close to 1mHz during some LTP experiments. In this paper we report on how these kind of Thermal Diagnostics experiments were simulated in the last LPF Simulation Campaign (November, 2013) involving all the LPF Data Analysis team and using an end-to-end simulator of the whole spacecraft. Such simulation campaign was conducted under the framework of the preparation for LPF operations. Spanish Ministry of Science and Innovation (MICINN)/AYA2010-15709
Published: 2015
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42. Planck view of the M 82 galaxy

Author: Asghar Qadir, S. Sargsyan, Daniele Vetrugno, A. L. Kashin, F. De Paolis, Vahe Gurzadyan, G. Yegorian, Ph. Jetzer, H. G. Khachatryan, A. A. Nucita, G. Ingrosso, Gurzadyan, V. G., DE PAOLIS, Francesco, Nucita, Achille, Ingrosso, Gabriele, Kashin, A. L., Khachatryan, H. G., Sargsyan, S., Yegorian, G., Jetzer, P. h., Qadir, A., and Vetrugno, Daniele
Subjects: Physics, Spiral galaxy, media_common.quotation_subject, Galactic Center, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Astrophysics - Astrophysics of Galaxies, Asymmetry, Galaxy, symbols.namesake, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), symbols, Halo, Planck, Astrophysics::Galaxy Astrophysics, media_common, general [galaxies]
Abstract: Planck data towards the galaxy M82 are analyzed in the 70, 100 and 143 GHz bands. A substantial north-south and East-West temperature asymmetry is found, extending up to 1 degree from the galactic center. Being almost frequency-independent, these temperature asymmetries are indicative of a Doppler-induced effect regarding the line-of-sight dynamics on the halo scale, the ejections from the galactic center and, possibly, even the tidal interaction with M81 galaxy. The temperature asymmetry thus acts as a model-independent tool to reveal the bulk dynamics in nearby edge-on spiral galaxies, like the Sunyaev-Zeldovich effect for clusters of galaxies., 4 pages, 3 figures, in press on A&A
Published: 2015

43. The free-fall mode experiment on LISA Pathfinder: first results

Author: Daniele Vetrugno and Antonella Cavalleri
Subjects: Physics, History, Spacecraft, 010308 nuclear & particles physics, business.industry, Acoustics, Mode (statistics), 01 natural sciences, Computer Science Applications, Education, Noise, Acceleration, Pathfinder, 0103 physical sciences, Data analysis, Orbit (dynamics), Calibration, 010306 general physics, business
Abstract: The LISA Pathfinder space mission is testing the critical experimental challenge for LISA by measuring the differential acceleration between two free-falling test masses inside a single co-orbiting spacecraft at a level of sub-femto-g for frequencies down to 0.1mHz. In LPF it is necessary that one test mass (TM) is electrostatically forced to follow the orbit of the other TM. This force represents a noise source in differential acceleration at frequencies below 1mHz. The free-fall mode experiment has been performed in order to reduce this source of noise: the actuation is limited to short impulses on one TM, so that it is in free fall between two successive kicks, while the other TM is drag-free. The free-fall mode thus provides a different technique for measuring the differential TM acceleration without the added force noise and calibration issues introduced by the actuator. Data analysis challenge is related to the presence of the kicks: they represent a high-noise contribution and need to be removed, thus leaving short gaps in data. This article presents preliminary data of the LPF free-fall measurement campaign and describes the three data analysis techniques developed to mitigate the presence of gaps.
Published: 2017

44. A two-stage torsion pendulum for ground testing free fall conditions on two degrees of freedom

Author: Daniele Vetrugno, F. Garufi, Rosario De Rosa, Fabrizio De Marchi, Rita Dolesi, Massimo Bassan, Massimo Visco, Leopoldo Milano, Giuseppe Pucacco, W. J. Weber, Luciano Di Fiore, N. Finetti, Aniello Grado, Martina De Laurentis, Stefano Vitale, Antonella Cavalleri, Mauro Hueller, Ruggero Stanga, Bassan, M., Cavalleri, A., De Laurentis, M., De Marchi, F., De Rosa, R., Di Fiore, L., Dolesi, R., Finetti, N., Garufi, F., Grado, A., Hueller, M., Milano, L., Pucacco, G., Stanga, R., Vetrugno, D., Visco, M., Vitale, S., Weber, W. J., Bassan, M, Cavalleri, A, DE LAURENTIS, Martina, De Marchi, F, DE ROSA, Rosario, Di Fiore, L, Dolesi, R, Finetti, N, Garufi, Fabio, Grado, A, Hueller, M, Milano, Leopoldo, Pucacco, G, Stanga, R, Vetrugno, D, Visco, M, Vitale, S, and Weber, Jw
Subjects: Ground testing, Nuclear and High Energy Physics, History, inertial sensor, free-fall, Torsion pendulum, 01 natural sciences, Education, Gravitation, Control theory, 0103 physical sciences, Torque, 010306 general physics, Physics, 010308 nuclear & particles physics, Gravitational wave, Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, space gravitational-wave detectors, Torsion (mechanics), Computer Science Applications, Two degrees of freedom, Classical mechanics, Torsion pendulum clock, Reference sensor, Stage (hydrology), space gravitational-wave detector
Abstract: A torsion pendulum with 2 soft degrees of freedom (DOF), realized by off-axis cascading two torsion fibers, has been built and operated. This instrument allows simultaneous measurement of force and torque acting on the suspended test mass, approaching free-fall condition down to a few mHz. It was developed for ground testing on two DOFs, before the launch, of the Gravitational Reference Sensor of the LISA-Pathfinder mission. We will report on the results of some measurement campaigns devoted in particular to the characterization of force to torque and torque to force actuation cross-talks. We will also indicate further possible upgrades of the facility for application for ground testing of future space gravitational wave antennas or other space experiments requiring drag-free control.
Published: 2017

45. LISA Pathfinder first results

Author: Daniele Vetrugno and Stefano Vitale
Subjects: Physics, Gravitational-wave observatory, 010308 nuclear & particles physics, Gravitational wave, Launched, Astronomy, Astronomy and Astrophysics, Laser interferometer space antenna, Space (mathematics), 01 natural sciences, Interferometry, Pathfinder, Space and Planetary Science, 0103 physical sciences, 010306 general physics, Mathematical Physics
Abstract: LISA Pathfinder (LPF) is an in-flight technological demonstrator designed and launched to prove the feasibility of sub-femto-[Formula: see text] free fall of kilo-sized test masses (TM), an essential ingredient for the future gravitational wave observatory from space. Half a year after launch, the first results are available and show an incredibly well-performing instrument. The results represent a first and important step towards the long awaited construction and launch of LISA, the Laser Interferometer Space Antenna.
Published: 2017

46. Data series subtraction with unknown and unmodeled background noise

Author: Valerio Ferroni, Oliver Jennrich, Michele Armano, James Ira Thorpe, Nikolaos Karnesis, N. Korsakova, Henri Inchauspe, Paul McNamara, Ingo Diepholz, Ferran Gibert, Stefano Vitale, G. Congedo, Luigi Ferraioli, Eric Plagnol, Heather Audley, W. J. Weber, Daniele Vetrugno, Mauro Hueller, Miquel Nofrarías, Peter Wass, Martin Hewitson, Rita Dolesi, Karsten Danzmann, Department of Physics and INFN, University of Trento [Trento], AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-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), Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut ) (AEI), Max-Planck-Gesellschaft, Astrophysique Relativiste Théories Expériences Métrologie Instrumentation Signaux (ARTEMIS), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Centre de Recerca en Sanitat Animal (CReSA), Agence Spatiale Européenne = European Space Agency (ESA), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Nice Sophia Antipolis (... - 2019) (UNS), Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne (ESA), and European Space Agency (ESA)
Subjects: Physics, [PHYS]Physics [physics], Nuclear and High Energy Physics, FOS: Physical sciences, Spectral density, Probability density function, General Relativity and Quantum Cosmology (gr-qc), Residual, General Relativity and Quantum Cosmology, Fast inverse square root, Background noise, Acceleration, Classical mechanics, Astrophysics - Instrumentation and Methods for Astrophysics, Likelihood function, Linear combination, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Instrumentation and Methods for Astrophysics (astro-ph.IM), Algorithm, ComputingMilieux_MISCELLANEOUS
Abstract: LISA Pathfinder (LPF), ESA's precursor mission to a gravitational wave observatory, will measure the degree to which two test-masses can be put into free-fall, aiming to demonstrate a residual relative acceleration with a power spectral density (PSD) below 30 fm/s$^2$/Hz$^{1/2}$ around 1 mHz. In LPF data analysis, the measured relative acceleration data series must be fit to other various measured time series data. This fitting is required in different experiments, from system identification of the test mass and satellite dynamics to the subtraction of noise contributions from measured known disturbances. In all cases, the background noise, described by the PSD of the fit residuals, is expected to be coloured, requiring that we perform such fits in the frequency domain. This PSD is unknown {\it a priori}, and a high accuracy estimate of this residual acceleration noise is an essential output of our analysis. In this paper we present a fitting method based on Bayesian parameter estimation with an unknown frequency-dependent background noise. The method uses noise marginalisation in connection with averaged Welch's periodograms to achieve unbiased parameter estimation, together with a consistent, non-parametric estimate of the residual PSD. Additionally, we find that the method is equivalent to some implementations of iteratively re-weighted least-squares fitting. We have tested the method both on simulated data of known PSD, and to analyze differential acceleration from several experiments with the LISA Pathfinder end-to-end mission simulator., To appear Phys. Rev. D90 August 2014
Published: 2014

47. A noise simulator for eLISA: Migrating LISA Pathfinder knowledge to the eLISA mission

Author: Ferran Gibert, Daniele Vetrugno, H. Ward, Peter Wass, P. Pivato, S. Wen, Tobias Ziegler, J. Reiche, J. Gallegos, N. Korsakova, A. Cesarini, G. Russano, Gerhard Heinzel, Michele Armano, Michael Perreur-Lloyd, B. Kaune, Antoine Petiteau, S. Madden, M. Freschi, N. Brandt, Paul McNamara, Luigi Ferraioli, S. Paczkowski, Henri Inchauspe, Peter Zweifel, Nikolaos Karnesis, S. Waschke, A. Moroni, Tamara Sumner, Carlos F. Sopuerta, R. Giusteri, Ph. Jetzer, Christian J. Killow, José F. F. Mendes, U. Ragnit, J. Huesler, Daniele Bortoluzzi, L. Mendes, Ivan Lloro, Ignacio Mateos, Heather Audley, C. García Marirrodriga, P. Sarra, A. Schleicher, I. Harrison, H. B. Tu, Miquel Nofrarías, Pierre Binétruy, Rita Dolesi, Mauro Hueller, B. Johlander, Karsten Danzmann, Davor Mance, W. J. Weber, C. Trenkel, Jacob Slutsky, Valerio Ferroni, N. Dunbar, Catia Grimani, D. Texier, C. Zanoni, D. Wealthy, R. Gerndt, Martin Hewitson, Daniel Hollington, Oliver Jennrich, Ewan Fitzsimons, J. Baird, S. Vitale, Antonella Cavalleri, M. Cruise, P. Prat, A. Bursi, F. Martin-Porqueras, Lluis Gesa, G. Auger, R. Maarschalkerweerd, A. Wittchen, H. Rozemeijer, James Ira Thorpe, Domenico Giardini, J. A. Romera Perez, Eric Plagnol, V. Martín, M. Caleno, D. I. Robertson, Gudrun Wanner, Juan Ramos-Castro, M. Born, Ingo Diepholz, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)
Subjects: History, noise, Astronomy, Residual, Astrophysics, programming, LISA Pathfinder, Education, Physics, Applied, System imperfections, Acceleration, Simulators, numerical methods, State space, ddc:530, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], MATLAB, Instrumental noise, numerical calculations, Simulation, Dewey Decimal Classification::500 | Naturwissenschaften, Konferenzschrift, computer.programming_language, Constellation, Physics, LISA, Spacecraft, business.industry, Noise (signal processing), Computer Science Applications, Pathfinder, Free fall, [PHYS.GRQC]Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], On state, ddc:500, Dewey Decimal Classification::500 | Naturwissenschaften::530 | Physik, Residual acceleration, business, computer, Space probes, performance
Abstract: We present a new technical simulator for the eLISA mission, based on state space modeling techniques and developed in MATLAB. This simulator computes the coordinate and velocity over time of each body involved in the constellation, i.e. the spacecraft and its test masses, taking into account the different disturbances and actuations. This allows studying the contribution of instrumental noises and system imperfections on the residual acceleration applied on the TMs, the latter reflecting the performance of the achieved free-fall along the sensitive axis. A preliminary version of the results is presented. Sorbonne Paris Cite/UnivEarthS Labex French Space Agency (CNES)
Published: 2014

48. An XMM-Newton search for X-ray sources in the Fornax dwarf galaxy

Author: A. A. Nucita, G. Ingrosso, F. De Paolis, Daniele Vetrugno, L. Manni, Nucita, Achille, Manni, Luigi, DE PAOLIS, Francesco, Vetrugno, Daniele, and Ingrosso, Gabriele
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Active galactic nucleus, Accretion (meteorology), Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics - Astrophysics of Galaxies, Galaxy, Black hole, symbols.namesake, Black hole physic, Dwarf galaxie, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Globular cluster, Fornax Dsph, Eddington luminosity, symbols, Variable star, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics::Galaxy Astrophysics, Dwarf galaxy
Abstract: We report the results of a deep archive XMM-Newton observation of the Fornax spheroidal galaxy that we analyzed with the aim of fully characterizing the X-ray source population (in most of the cases likely to be background active galactic nuclei) detected towards the target. A cross correlation with the available databases allowed us to find a source that may be associated with a variable star belonging to the galaxy. We also searched for X-ray sources in the vicinity of the Fornax globular clusters GC 3 and GC 4 and found two sources probably associated with the respective clusters. The deep X-ray observation was also suitable for the search of the intermediate-mass black hole (of mass $\simeq 10^{4}$ M$_{\odot}$) expected to be hosted in the center of the galaxy. In the case of Fornax, this search is extremely difficult since the galaxy centroid of gravity is poorly constrained because of the large asymmetry observed in the optical surface brightness. Since we cannot firmly establish the existence of an X-ray counterpart of the putative black hole, we put constraints only on the accretion parameters. In particular, we found that the corresponding upper limit on the accretion efficiency, with respect to the Eddington luminosity, is as low as a few $10^{-5}$., In press on Astronomy and Astrophysics. 12 Pages, colour figures on the on-line version of the paper
Published: 2013

49. CMB as a possible new tool to study the dark baryons in galaxies

Author: Ph. Jetzer, Daniele Vetrugno, A. L. Kashin, H. G. Khachatryan, Vahe Gurzadyan, S. Mirzoyan, A. A. Nucita, G. Ingrosso, Asghar Qadir, F. De Paolis, F. De Paoli, A.A. Siddiqui, DE PAOLIS, Francesco, Ingrosso, Gabriele, Nucita, Achille, Vetrugno, Daniele, V. G., Gurzadyan, A. L., Kashin, H. G., Khachatryan, S., Mirzoyan, Jetzer, P. h., A., Qadir, University of Zurich, and De Paolis, F
Subjects: History, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 530 Physics, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Cosmic microwave background, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Cosmic background radiation, 01 natural sciences, Education, Galactic halo, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, media_common, Physics, Spiral galaxy, Baryonic dark matter, CMB cold spot, Universe, Galaxy, 3100 General Physics and Astronomy, Computer Science Applications, Baryon, 10231 Institute for Computational Science, Galactic halos, Halo, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Baryons constitute about 4% of our universe, but most of them are missing and we do not know where and in what form they are hidden. This constitute the so-called missing baryon problem. A possibility is that part of these baryons are hidden in galactic halos. We show how the 7-year data obtained by the WMAP satellite may be used to trace the halo of the nearby giant spiral galaxy M31. We detect a temperature asymmetry in the M31 halo along the rotation direction up to about 120 kpc. This could be the first detection of a galactic halo in microwaves and may open a new way to probe hidden baryons in these relatively less studied galactic objects using high accuracy CMB measurements., Comment: 8 pages, presented at the III Italian-Pakistani Workshop on Relativistic Astrophysics, Lecce, June 20-22, 2011; to be published in Journal of Physics: Conference Series
Published: 2012

50. A weakly random Universe?

Author: G. Yegorian, Vahe Gurzadyan, S. Mirzoyan, Daniele Vetrugno, H. G. Khachatryan, E. Poghosian, T. Ghahramanyan, A. L. Kashin, A. E. Allahverdyan, A. A. Kocharyan, and University of Zurich
Subjects: Physics, Cosmology and Nongalactic Astrophysics (astro-ph.CO), 530 Physics, media_common.quotation_subject, Cosmic microwave background, Isotropy, Astrophysics::Instrumentation and Methods for Astrophysics, Cosmic background radiation, FOS: Physical sciences, Astronomy and Astrophysics, Scale (descriptive set theory), General Relativity and Quantum Cosmology (gr-qc), Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, General Relativity and Quantum Cosmology, Universe, Amplitude, 1912 Space and Planetary Science, Space and Planetary Science, 10231 Institute for Computational Science, 3103 Astronomy and Astrophysics, Anisotropy, Randomness, Astrophysics - Cosmology and Nongalactic Astrophysics, media_common
Abstract: The cosmic microwave background (CMB) radiation is characterized by well-established scales, the 2.7 K temperature of the Planckian spectrum and the $10^{-5}$ amplitude of the temperature anisotropy. These features were instrumental in indicating the hot and equilibrium phases of the early history of the Universe and its large scale isotropy, respectively. We now reveal one more intrinsic scale in CMB properties. We introduce a method developed originally by Kolmogorov, that quantifies a degree of randomness (chaos) in a set of numbers, such as measurements of the CMB temperature in some region. Considering CMB as a composition of random and regular signals, we solve the inverse problem of recovering of their mutual fractions from the temperature sky maps. Deriving the empirical Kolmogorov's function in the Wilkinson Microwave Anisotropy Probe's maps, we obtain the fraction of the random signal to be about 20 per cent, i.e. the cosmological sky is a weakly random one. The paper is dedicated to the memory of Vladimir Arnold (1937-2010)., Comment: 4 pages, 3 figs, A & A (Lett) in press; to match the published version
Published: 2011

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