GRAVITY: getting to the event horizon of Sgr A*

F. Eisenhauer; G. Perrin; W. Brandner; C. Straubmeier; A. Richichi; S. Gillessen; J. P. Berger; S. Hippler; A. Eckart; M. Schöller; S. Rabien; F. Cassaing; R. Lenzen; M. Thiel; Y. Clénet; J. R. Ramos; S. Kellner; P. Fédou; H. Baumeister; R. Hofmann; E. Gendron; A. Boehm; H. Bartko; X. Haubois; R. Klein; K. Dodds-Eden; K. Houairi; F. Hormuth; A. Gräter; L. Jocou; V. Naranjo; R. Genzel; P. Kervella; T. Henning; N. Hamaus; S. Lacour; U. Neumann; M. Haug; F. Malbet; W. Laun; J. Kolmeder; T. Paumard; R.-R. Rohloff; O. Pfuhl; K. Perraut; J. Ziegleder; D. Rouan; G. Rousset

doi:10.1117/12.788407

28 July 2008 GRAVITY: getting to the event horizon of Sgr A*

F. Eisenhauer, G. Perrin, W. Brandner, C. Straubmeier, A. Richichi, S. Gillessen, J. P. Berger, S. Hippler, A. Eckart, M. Schöller, S. Rabien, F. Cassaing, R. Lenzen, M. Thiel, Y. Clénet, J. R. Ramos, S. Kellner, P. Fédou, H. Baumeister, R. Hofmann, E. Gendron, A. Boehm, H. Bartko, X. Haubois, R. Klein, K. Dodds-Eden, K. Houairi, F. Hormuth, A. Gräter, L. Jocou, V. Naranjo, R. Genzel, P. Kervella, T. Henning, N. Hamaus, S. Lacour, U. Neumann, M. Haug, F. Malbet, W. Laun, J. Kolmeder, T. Paumard, R.-R. Rohloff, O. Pfuhl, K. Perraut, J. Ziegleder, D. Rouan, G. Rousset

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Proceedings Volume 7013, Optical and Infrared Interferometry; 70132A (2008) https://doi.org/10.1117/12.788407
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

Abstract

We present the second-generation VLTI instrument GRAVITY, which currently is in the preliminary design phase. GRAVITY is specifically designed to observe highly relativistic motions of matter close to the event horizon of Sgr A*, the massive black hole at center of the Milky Way. We have identified the key design features needed to achieve this goal and present the resulting instrument concept. It includes an integrated optics, 4-telescope, dual feed beam combiner operated in a cryogenic vessel; near infrared wavefront sensing adaptive optics; fringe tracking on secondary sources within the field of view of the VLTI and a novel metrology concept. Simulations show that the planned design matches the scientific needs; in particular that 10µas astrometry is feasible for a source with a magnitude of K=15 like Sgr A*, given the availability of suitable phase reference sources.

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F. Eisenhauer, G. Perrin, W. Brandner, C. Straubmeier, A. Richichi, S. Gillessen, J. P. Berger, S. Hippler, A. Eckart, M. Schöller, S. Rabien, F. Cassaing, R. Lenzen, M. Thiel, Y. Clénet, J. R. Ramos, S. Kellner, P. Fédou, H. Baumeister, R. Hofmann, E. Gendron, A. Boehm, H. Bartko, X. Haubois, R. Klein, K. Dodds-Eden, K. Houairi, F. Hormuth, A. Gräter, L. Jocou, V. Naranjo, R. Genzel, P. Kervella, T. Henning, N. Hamaus, S. Lacour, U. Neumann, M. Haug, F. Malbet, W. Laun, J. Kolmeder, T. Paumard, R.-R. Rohloff, O. Pfuhl, K. Perraut, J. Ziegleder, D. Rouan, and G. Rousset "GRAVITY: getting to the event horizon of Sgr A*", Proc. SPIE 7013, Optical and Infrared Interferometry, 70132A (28 July 2008); https://doi.org/10.1117/12.788407

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