Publication: Constraints on graviton mass and a tidal charge with observations of the galactic center
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2019
Авторы
Zakharov, A. F.
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© Proceedings of the 54th Rencontres de Moriond - 2019 Gravitation.General relativity (GR) created by A. Einstein more than 100 year ago and it is the best theory of gravity since it successfully passed a number of tests. However, GR has been verified rather well in a weak gravitational field approximation where GR predictions could practically be very similar to predictions of many alternative theories of gravity. Really, in November 1915 Einstein remarkably explained the Mercury anomaly found by Le Verrier in the mid of XIX century. Both phenomena were explained in the framework of the first post-Newtonian approximation of GR. Soon after that Eddington and Dyson confirmed GR predictions about deflections of light by gravitational field of Sun with observations of foreground stars during the Solar eclipse in May 1919. After that Einstein started to be a world celebrity since he corrected Newton introducing a new description of gravity law. Therefore, if we assume that GR and Newtonian gravity law are universal than we have conclude that GR is preferable. After that GR has been tested in many observations and experiments but as we note basically in a weak gravitational field approximation. For instance, recently the GRAVITY collaboration and the Keck team confirmed GR predictions for gravitational redshift in the first post-Newtonian for S2 star near its pericenter passage in May 2018 (S2 star moves around the supermassive black hole at the Galactic Center). Similarly the the Eddington's claim about a preference of GR in comparison with Newtonian theory, the GRAVITY noted that gravitational redshift of the S2 star is better described with GR. In April 2019 the Event Horizon Telescope collaboration reported about a shadow reconstruction at the center of galaxy M87 and shadow sizes correspond to estimates obtained with a GR approach. We discuss opportunities to constrain alternative theories of gravity with current and forthcoming observations of the Galactic Center (GC) (and the center of M87) with large telescopes in IR band and VLBI network. Among many other alternatives theories of massive gravity are considered as alternatives for GR. For instance, some time ago the LIGO - Virgo collaboration discovered gravitational waves and binary black holes and also found an upper constraint on graviton mass mg < 1.2 × 10−22 eV (and later the estimate was improved mg < 7 × 10−23 eV). If we analyze pericenter shifts evaluated from observations and theoretical values calculated assuming Yukawa potential corresponding to a massive graviton then in the future one could reach a graviton mass estimate as low as mg < 5 × 10−23 eV. Similarly, evaluating pecicenter shifts for bright star orbits around the black hole at the Galactic Center one could constrain a tidal charge for the black hole. Therefore, analyzing sizes of shadows around the supermassive black hole at the Galactic Center (or/and in the center of M87) one could constrain parameters of different alternative theories of gravity as well.
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Zakharov, A. F. Constraints on graviton mass and a tidal charge with observations of the galactic center / Zakharov, A.F. // Proceedings of the 54th Rencontres de Moriond - 2019 Gravitation. - 2019. - P. 85-88