Gravitational lensing of a star by a rotating black hole

Abstract

The gravitational lensing of a finite star moving around a rotating Kerr black hole has been numerically calculated. Calculations for the direct image of the star and for the first and This will simultaneously provide an experimental strong field test of not only the general relativity but also many other theories of gravity, e.g., f (R), C 2 , Galilean, Horndeski, mimetic, and multidimensional (see, e.g., [38][39][40][41][42][43][44][45][46][47][48][49][50] and/or hot gas clouds near the black hole [63][64][65][66][67][68][69][70] with the data from a Millimetron-type interferometer soon will make it possible to reliably verify (falsify) the known theories of gravity.We numerically calculated the gravitational

Event Horizon Image within Black Hole Shadow

“…The black hole shadow is revealed by observations (e. g., in the X-rays or in the near far Infra-Red) of the foreground sources, e. g., the gravitationally lensed images of normal stars or neutron stars behind the black hole, which are moving around black hole on the stationary orbits. This possibility is illustrated in figure 2 and in the corresponding animated numerical simulation [56,57].…”

“…Direct star images and also the first and second light echoes around the black hole shadow (filled gray region) are shown in discrete time intervals. For details see [56,57].…”

“…See [48][49][50][51][52] for corresponding examples of analytical computations for null geodesics in the Kerr space-time. An example of numerical gravitational lensing animation of the compact star orbiting the rotating black hole see at [56,57]. See in Fig.…”

Observational tests of general relativity and alternative theories of gravity with Galactic Center observations using current and future large observational facilities

“…For instance, Hioki and Maeda (2009) proposed to use such parameters (radius and distortion parameter for shadows) to evaluate the black hole spin from observations. Therefore, evaluations of the shadow sizes around the black holes could help to estimate of the black hole parameters (Zakharov et al, 2005a,b;Zakharov, 2014Zakharov, , 2015Cherepashchuk, 2016Cherepashchuk, , 2017Bisnovatyi-Kogan & Tsupko, 2017;Dokuchaev & Nazarova, 2017;Cunha & Herdeiro, 2018;Shaikh, 2018Shaikh, , 2019Dokuchaev & Nazarova, 2019). Opportunities to compare predictions of general relativity and alternative theories of gravity with measuring the shadow size for the black hole at the Galactic Center has been discussed by Zakharov et al (2012); Johannsen et al (2016).…”

General relativistic formulas for mass and spin of a Kerr black hole in terms of redshifts and orbital parameters

“…During last decades, we have witnessed a growing interest in the search for astrophysical black holes, whose existence has become a fundamental scientific issue, as well as for different methods to characterize their parameters (Dokuchaev & Nazarova 2017; Eckart & Genzel 1996; Genzel et al 2003; Ghez et al 2008; Morris et al 2012; Shen et al 2005). On the one hand, there is a vast dynamic evidence indicating that in each galaxy there are millions of black holes with stellar masses; besides, at the center of almost all galaxies there seems to exist a supermassive black hole (SMBH) with masses that range from millions to billions of solar masses, including a black hole hosted at the center of the Milky Way, called SgrA* (Begelman 2003).…”