Improving constraints on the extended mass distribution in the Galactic center with stellar orbits,Astronomy & Astrophysics

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Improving constraints on the extended mass distribution in the Galactic center with stellar orbits
Astronomy & Astrophysics ( IF 5.4 ) Pub Date : 2024-12-17 , DOI: 10.1051/0004-6361/202452274
K. Abd El Dayem, R. Abuter, N. Aimar, P. Amaro Seoane, A. Amorim, J. Beck, J. P. Berger, H. Bonnet, G. Bourdarot, W. Brandner, V. Cardoso, R. Capuzzo Dolcetta, Y. Clénet, R. Davies, P. T. de Zeeuw, A. Drescher, A. Eckart, F. Eisenhauer, H. Feuchtgruber, G. Finger, N. M. Förster Schreiber, A. Foschi, F. Gao, P. Garcia, E. Gendron, R. Genzel, S. Gillessen, M. Hartl, X. Haubois, F. Haussmann, G. Heißel, T. Henning, S. Hippler, M. Horrobin, L. Jochum, L. Jocou, A. Kaufer, P. Kervella, S. Lacour, V. Lapeyrère, J.-B. Le Bouquin, P. Léna, D. Lutz, F. Mang, N. More, T. Ott, T. Paumard, K. Perraut, G. Perrin, O. Pfuhl, S. Rabien, D. C. Ribeiro, M. Sadun Bordoni, S. Scheithauer, J. Shangguan, T. Shimizu, J. Stadler, O. Straub, C. Straubmeier, E. Sturm, L. J. Tacconi, I. Urso, F. Vincent, S. D. von Fellenberg, F. Widmann, E. Wieprecht, J. Woillez, F. Zhang

Studying the orbital motion of stars around Sagittarius A* in the Galactic center provides a unique opportunity to probe the gravitational potential near the supermassive black hole at the heart of our Galaxy. Interferometric data obtained with the GRAVITY instrument at the Very Large Telescope Interferometer (VLTI) since 2016 has allowed us to achieve unprecedented precision in tracking the orbits of these stars. GRAVITY data have been key to detecting the in-plane, prograde Schwarzschild precession of the orbit of the star S2 that is predicted by general relativity. By combining astrometric and spectroscopic data from multiple stars, including S2, S29, S38, and S55 – for which we have data around their time of pericenter passage with GRAVITY – we can now strengthen the significance of this detection to an approximately 10σ confidence level. The prograde precession of S2’s orbit provides valuable insights into the potential presence of an extended mass distribution surrounding Sagittarius A*, which could consist of a dynamically relaxed stellar cusp comprising old stars and stellar remnants, along with a possible dark matter spike. Our analysis, based on two plausible density profiles – a power-law and a Plummer profile – constrains the enclosed mass within the orbit of S2 to be consistent with zero, establishing an upper limit of approximately 1200 M_{⊙_{with a 1σ confidence level. This significantly improves our constraints on the mass distribution in the Galactic center. Our upper limit is very close to the expected value from numerical simulations for a stellar cusp in the Galactic center, leaving little room for a significant enhancement of dark matter density near Sagittarius A*.}}

中文翻译：

改善对恒星轨道银河系中心扩展质量分布的约束

研究银河系中心人马座 A* 周围恒星的轨道运动为探测银河系中心超大质量黑洞附近的引力势提供了独特的机会。自 2016 年以来，在甚大望远镜干涉仪（VLTI）上使用 GRAVITY 仪器获得的干涉数据使我们能够在跟踪这些恒星的轨道时实现前所未有的精度。GRAVITY 数据一直是检测广义相对论预测的恒星 S2 轨道的面内顺行 Schwarzschild 进动的关键。通过结合来自多颗恒星的天体测量和光谱数据，包括 S2、S29、S38 和 S55——我们掌握了它们通过 GRAVITY 经过周边时间的数据——我们现在可以将这次探测的重要性提高到大约 10σ 的置信度。S2 轨道的顺行岁差为人马座 A* 周围可能存在的扩展质量分布提供了有价值的见解，该分布可能包括一个由旧恒星和恒星残骸组成的动态松弛的恒星尖，以及可能的暗物质尖峰。我们的分析基于两个合理的密度曲线——幂律和 Plummer 曲线——将 S2 轨道内的封闭质量约束为零，建立了大约 1200 M⊙ 的上限和 1σ 的置信水平。这大大改善了我们对银河系中心质量分布的约束。我们的上限非常接近银河系中心恒星尖点的数值模拟预期值，几乎没有空间可以显着增强人马座 A* 附近的暗物质密度。