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3. Accelerations of stars in the central 2–7 arcsec from Sgr A*

Author

Young, A., primary, Gillessen, S., additional, de Zeeuw, T., additional, Dallilar, Y., additional, Drescher, A., additional, Eisenhauer, F., additional, Genzel, R., additional, Mang, F., additional, Ott, T., additional, Stadler, J., additional, Straub, O., additional, von Fellenburg, S., additional, and Widmann, F., additional

Published
2023
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4. A kinematically detected planet candidate in a transition disk

Author

Stadler, J., primary, Benisty, M., additional, Izquierdo, A., additional, Facchini, S., additional, Teague, R., additional, Kurtovic, N., additional, Pinilla, P., additional, Bae, J., additional, Ansdell, M., additional, Loomis, R., additional, Mayama, S., additional, Perez, L. M., additional, and Testi, L., additional

Published
2023
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5. Flaremodel: An open-source Python package for one-zone numerical modelling of synchrotron sources

Author

Dallilar, Y., primary, von Fellenberg, S., additional, Bauboeck, M., additional, de Zeeuw, P. T., additional, Drescher, A., additional, Eisenhauer, F., additional, Genzel, R., additional, Gillessen, S., additional, Habibi, M., additional, Ott, T., additional, Ponti, G., additional, Stadler, J., additional, Straub, O., additional, Widmann, F., additional, Witzel, G., additional, and Young, A., additional

Published
2022
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6. Characterizing the morphology of the debris disk around the low-mass star GSC 07396-00759

Author

Lacour, S., Wang, J., Rodet, L., Nowak, M., Shangguan, J., Beust, H., Lagrange, A.-M., Abuter, R., Amorim, A., Asensio-Torres, R., Benisty, M., Berger, J.-P., Blunt, S., Boccaletti, A., Bohn, A., Bolzer, M.-L., Bonnefoy, M., BONNET, H., Bourdarot, G., Brandner, W., Cantalloube, F., Caselli, P., Charnay, B., Chauvin, G., Choquet, E., Christiaens, V., Clénet, Y., Coudé Du Foresto, V., Cridland, A., Dembet, R., Dexter, J., de Zeeuw, P., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Garcia, P., Garcia Lopez, R., Gendron, E., Genzel, R., Gillessen, S., Girard, J., Haubois, X., Heißel, G., Henning, Th., Hinkley, S., Hippler, S., Horrobin, M., Houllé, M., Hubert, Z., Jocou, L., Kammerer, J., Keppler, M., Kervella, P., Kreidberg, L., Lapeyrère, V., Le Bouquin, J.-B., Léna, P., Lutz, D., Maire, A.-L., Mérand, A., Mollière, P., Monnier, J., Mouillet, D., Nasedkin, E., Ott, T., Otten, G., Paladini, C., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rickman, E., Pueyo, L., Rameau, J., Rousset, G., Rustamkulov, Z., Samland, M., Shimizu, T., Sing, D., Stadler, J., Stolker, T., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L., Van Dishoeck, E., Vigan, A., Vincent, F., Von fellenberg, S., Ward-Duong, K., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., Adam, C., Olofsson, J., van Holstein, R., Bayo, A., Milli, J., Kral, Q., Ginski, C., Montesinos, M., Pawellek, N., Zurlo, A., Langlois, M., Delboulbé, A., Pavlov, A., Ramos, J., Weber, L., Wildi, F., Rigal, F., Sauvage, J.-F., Pawellek, Nicole [0000-0002-9385-9820], Apollo - University of Cambridge Repository, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Low Energy Astrophysics (API, FNWI), and Faculteit der Geesteswetenschappen

Subjects
010504 meteorology & atmospheric sciences, FOS: Physical sciences, Outflows, Context (language use), Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, circumstellar matter, techniques: photometric, 0103 physical sciences, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Debris disk, stars: winds, outflows, techniques: high angular resolution, Astronomy and Astrophysics, Radius, Stars: winds, Grain size, Stars, stars: individual: GSC 07396-00759, Astrophysics - Solar and Stellar Astrophysics, [SDU]Sciences of the Universe [physics], Space and Planetary Science, radiative transfer, Scattering theory, Astrophysics::Earth and Planetary Astrophysics, Low Mass, Astrophysics - Earth and Planetary Astrophysics
Abstract

Context. Debris disks have commonly been studied around intermediate-mass stars. Their intense radiation fields are believed to efficiently remove the small dust grains that are constantly replenished by collisions. For lower-mass stars, in particular M-stars, the dust removal mechanism needs to be further investigated given the much weaker radiation field produced by these objects. Aims. We present new polarimetric observations of the nearly edge-on disk around the pre-main sequence M-type star GSC 07396-00759, taken with VLT/SPHERE IRDIS, with the aim to better understand the morphology of the disk, its dust properties, and the star-disk interaction via the stellar mass-loss rate. Methods. We model our observations to characterize the location and properties of the dust grains using the Henyey-Greenstein approximation of the polarized phase function and evaluate the strength of the stellar winds. Results. We find that the observations are best described by an extended and highly inclined disk ($i\approx 84.3\,^{\circ}\pm0.3$) with a dust distribution centered at a radius $r_{0}\approx107\pm2$ au. The polarized phase function $S_{12}$ is best reproduced by an anisotropic scattering factor $g\approx0.6$ and small micron-sized dust grains with sizes $s>0.3\,\mathrm��$m. We furthermore discuss some of the caveats of the approach and a degeneracy between the grain size and the porosity. Conclusions. Even though the radius of the disk may be over-estimated, our results suggest that using a given scattering theory might not be sufficient to fully explain key aspects such as the shape of the phase function, or the dust grain size. With the caveats in mind, we find that the average mass-loss rate of GSC 07396-00759 can be up to 500 times stronger than that of the Sun, supporting the idea that stellar winds from low-mass stars can evacuate small dust grains from the disk., 22 pages, 17 figures, 4 tables

Published
2021
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7. GRAVITY K-band spectroscopy of HD 206893 B

Author

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

Published
2021
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8. Mass distribution in the Galactic Center based on interferometric astrometry of multiple stellar orbits

Author

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

Subjects
Astrophysics - instrumentation and methods for astrophysics, Astrophysics and Astronomy, General Relativity and Cosmology, Astrophysics::High Energy Astrophysical Phenomena, gr-qc, astro-ph.GA, Astrophysics - astrophysics of galaxies, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Black hole physics, Instrumentation - interferometers, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, General relativity and quantum cosmology, Astrophysics::Galaxy Astrophysics, Galaxy - center, astro-ph.IM
Abstract

Stars orbiting the compact radio source Sgr A* in the Galactic Center serve as precision probes of the gravitational field around the closest massive black hole. In addition to adaptive optics-assisted astrometry (with NACO/VLT) and spectroscopy (with SINFONI/VLT, NIRC2/Keck and GNIRS/Gemini) over three decades, we have obtained 30–100 μas astrometry since 2017 with the four-telescope interferometric beam combiner GRAVITY/VLTI, capable of reaching a sensitivity of mK = 20 when combining data from one night. We present the simultaneous detection of several stars within the diffraction limit of a single telescope, illustrating the power of interferometry in the field. The new data for the stars S2, S29, S38, and S55 yield significant accelerations between March and July 2021, as these stars pass the pericenters of their orbits between 2018 and 2023. This allows for a high-precision determination of the gravitational potential around Sgr A*. Our data are in excellent agreement with general relativity orbits around a single central point mass, M• = 4.30 × 106 M⊙, with a precision of about ±0.25%. We improve the significance of our detection of the Schwarzschild precession in the S2 orbit to 7σ. Assuming plausible density profiles, the extended mass component inside the S2 apocenter (≈0.23″ or 2.4 × 104 RS) must be ≲3000 M⊙ (1σ), or ≲0.1% of M•. Adding the enclosed mass determinations from 13 stars orbiting Sgr A* at larger radii, the innermost radius at which the excess mass beyond Sgr A* is tentatively seen is r ≈ 2.5″ ≥ 10× the apocenter of S2. This is in full harmony with the stellar mass distribution (including stellar-mass black holes) obtained from the spatially resolved luminosity function.Key words: black hole physics / instrumentation: interferometers / Galaxy: center⋆ GRAVITY is developed in a collaboration by MPE, LESIA of Paris Observatory/CNRS/Sorbonne Université/Univ. Paris Diderot and IPAG of Université Grenoble Alpes/CNRS, MPIA, Univ. of Cologne, CENTRA – Centro de Astrofisica e Gravitação, and ESO.⋆⋆ Corresponding authors: S. Gillessen (e-mail: ste@mpe.mpg.de), F. Widmann (e-mail: fwidmann@mpe.mpg.de), and G. Heißel (e-mail: gernot.heissel@obspm.fr). The stars orbiting the compact radio source Sgr A* in the Galactic Centre are precision probes of the gravitational field around the closest massive black hole. In addition to adaptive optics assisted astrometry (with NACO / VLT) and spectroscopy (with SINFONI / VLT, NIRC2 / Keck and GNIRS / Gemini) over three decades, since 2016/2017 we have obtained 30-100 mu-as astrometry with the four-telescope interferometric beam combiner GRAVITY / VLTI reaching a sensitivity of mK = 20 when combining data from one night. We present the simultaneous detection of several stars within the diffraction limit of a single telescope, illustrating the power of interferometry. The new data for the stars S2, S29, S38 and S55 yield significant accelerations between March and July 2021, as these stars pass the pericenters of their orbits between 2018 and 2023. This allows for a high-precision determination of the gravitational potential around Sgr A*. Our data are in excellent agreement with general relativity orbits around a single central point mass, M = 4.30 x 10^6 M_sun with a precision of about +-0.25%. We improve the significance of our detection of the Schwarzschild precession in the S2 orbit to 7 sigma. Assuming plausible density profiles, an extended mass component inside S2's apocentre (= 0.23" or 2.4 x 10^4 R_S) must be 3000 M_sun (1 sigma), or 0.1% of M. Adding the enclosed mass determinations from 13 stars orbiting Sgr A* at larger radii, the innermost radius at which the excess mass beyond Sgr A* tentatively is seen is r = 2.5" >= 10x the apocentre of S2. This is in full harmony with the stellar mass distribution (including stellar-mass black holes) obtained from the spatially resolved luminosity function.

Published
2022
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9. Deep images of the Galactic center with GRAVITY

Author

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

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

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

Published
2022
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10. The GRAVITY young stellar object survey

Author

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

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

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

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

Author

The GRAVITY Collaboration, Baub��ck, M., Dexter, J., Abuter, R., Amorim, A., Berger, J. P., Bonnet, H., Brandner, W., Cl��net, Y., Foresto, V. Coud�� du, de Zeeuw, P. T., Duvert, G., Eckart, A., Eisenhauer, F., Schreiber, N. M. F��rster, Gao, F., Garcia, P., Gendron, E., Genzel, R., Gerhard, O., Gillessen, S., Habibi, M., Haubois, X., Henning, T., Hippler, S., Horrobin, M., Jim��nez-Rosales, A., Jocou, L., Kervella, P., Lacour, S., Lapeyr��re, V., Bouquin, J. -B. Le, L��na, P., Ott, T., Paumard, T., Perraut, K., Perrin, G., Pfuhl, O., Rabien, S., Coira, G. Rodriguez, Rousset, G., Scheithauer, S., Stadler, J., Sternberg, A., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L. J., Vincent, F., von Fellenberg, S., Waisberg, I., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), GRAVITY, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)

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

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

Published
2020
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12. The GRAVITY young stellar object survey

Author

Caratti O Garatti, A., Fedriani, R., Garcia Lopez, R., Koutoulaki, M., Perraut, K., Linz, H., Brandner, W., Garcia, P., Klarmann, L., Henning, T., Labadie, L., Sanchez-Bermudez, J., Lazareff, B., Van Dishoeck, E., Caselli, P., de Zeeuw, P., Bik, A., Benisty, M., Dougados, C., Ray, T., Amorim, A., Berger, J.-P., Clénet, Y., Coudé Du Foresto, V., Duvert, G., Eckart, A., Eisenhauer, F., Gao, F., Gendron, E., Genzel, R., Gillessen, S., Gordo, P., Jocou, L., Horrobin, M., Kervella, P., Lacour, S., Le Bouquin, J.-B., Léna, P., Grellmann, R., Ott, T., Paumard, T., Perrin, G., Rousset, G., Scheithauer, S., Shangguan, J., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Thi, W., Vincent, F., Widmann, F., Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, 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
[SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

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13. First light for GRAVITY Wide

Author

Abuter, R., Allouche, F., Amorim, A., Bailet, C., Bauböck, M., Berger, J.-P., Berio, P., Bigioli, A., Boebion, O., Bolzer, M. L., Bonnet, H., Bourdarot, G., Bourget, P., Brandner, W., Clénet, Y., Courtney-Barrer, B., Dallilar, Y., Davies, R., Defrère, D., Delboulbé, A., Delplancke, F., Dembet, R., de Zeeuw, P. T., Drescher, A., Eckart, A., Édouard, C., Eisenhauer, F., Fabricius, M., Feuchtgruber, H., Finger, G., Förster Schreiber, N. M., Garcia, E., Garcia, P., Gao, F., Gendron, E., Genzel, R., Gil, J. P., Gillessen, S., Gomes, T., Gonté, F., Gouvret, C., Guajardo, P., Guieu, S., Hartl, M., Haubois, X., Haußmann, F., Heißel, G., Henning, Th., Hippler, S., Hönig, S., Horrobin, M., Hubin, N., Jacqmart, E., Jochum, L., Jocou, L., Kaufer, A., Kervella, P., Korhonen, H., Kreidberg, L., Lacour, S., Lagarde, S., Lai, O., Lapeyrère, V., Laugier, R., Le Bouquin, J.-B., Leftley, J., Léna, P., Lutz, D., Mang, F., Marcotto, A., Maurel, D., Mérand, A., Millour, F., More, N., Nowacki, H., Nowak, M., Oberti, S., Ott, T., Pallanca, L., Pasquini, L., Paumard, T., Perraut, K., Perrin, G., Petrov, R., Pfuhl, O., Pourré, N., Rabien, S., Rau, C., Robbe-Dubois, S., Rochat, S., Salman, M., Schöller, M., Schubert, J., Schuhler, N., Shangguan, J., Shimizu, T., Scheithauer, S., Sevin, A., Soulez, F., Spang, A., Stadler, E., Stadler, J., Straubmeier, C., Sturm, E., Tacconi, L. J., Tristram, K. R. W., Vincent, F., von Fellenberg, S., Uysal, S., Widmann, F., Wieprecht, E., Wiezorrek, E., Woillez, J., Yazici, S., Young, A., and Zins, G.

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14. The GRAVITY young stellar object survey

Author

Perraut, K., Labadie, L., Bouvier, J., Ménard, F., Klarmann, L., Dougados, C., Benisty, M., Berger, J.-P., Bouarour, Y.-I., Brandner, W., Caratti o Garatti, A., Caselli, P., de Zeeuw, P. T., Garcia-Lopez, R., Henning, T., Sanchez-Bermudez, J., Sousa, A., van Dishoeck, E., Alécian, E., Amorim, A., Clénet, Y., Davies, R., Drescher, A., Duvert, G., Eckart, A., Eisenhauer, F., Förster-Schreiber, N. M., Garcia, P., Gendron, E., Genzel, R., Gillessen, S., Grellmann, R., Heißel, G., Hippler, S., Horrobin, M., Hubert, Z., Jocou, L., Kervella, P., Lacour, S., Lapeyrère, V., Le Bouquin, J.-B., Léna, P., Lutz, D., Ott, T., Paumard, T., Perrin, G., Scheithauer, S., Shangguan, J., Shimizu, T., Stadler, J., Straub, O., Straubmeier, C., Sturm, E., Tacconi, L., Vincent, F., von Fellenberg, S., and Widmann, F.

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