Visible Shapes of Black Holes M87* and SgrA*

Abstract

We review the physical origins for possible visible images of the supermassive black hole M87* in the galaxy M87 and SgrA* in the Milky Way Galaxy. The classical dark black hole shadow of the maximal size is visible in the case of luminous background behind the black hole at the distance exceeding the so-called photon spheres. The notably smaller dark shadow (dark silhouette) of the black hole event horizon is visible if the black hole is highlighted by the inner parts of the luminous accreting matter inside the photon spheres. The first image of the supermassive black hole M87*, obtained by the Event Horizon Telescope collaboration, shows the lensed dark image of the southern hemisphere of the black hole event horizon globe, highlighted by accreting matter, while the classical black hole shadow is invisible at all. A size of the dark spot on the Event Horizon Telescope (EHT) image agrees with a corresponding size of the dark event horizon silhouette in a thin accretion disk model in the case of either the high or moderate value of the black hole spin, a≳0.75.

Modeling the motion of a bright spot in jets from black holes M87* and SgrA*

“…We incorporate the photon shift g(r, q) into the Cunningham-Bardeen formalism [53,54] for numerical calculation the energy flux detected by a distant observer from the moving blob of finite size. We also numerically calculate the elliptic deformation of the lensed prime image of the small spherical blob in the strong gravitational field of the Kerr black hole (see more details of these calculations in [58][59][60][61][62][63][64]) Some results of these calculations are illustrated in Figures 1-8 ans in numerical animation [65].…”

“…The light blue region is the lensed image of the whole black hole event horizon globe. The corresponding blue curves are meridians and parallels on the black hole event horizon globe (see [61][62][63][64] for more details).…”

“…The light blue region is the lensed image of the black hole event horizon globe's northern hemisphere. The boundary between the blue and light blue region is the lensed image of the equator on the event horizon globe (see [61][62][63][64] for more details).…”

Greybody factors of bosons and fermions emitted from higher dimensional dS/AdS black holes in Einstein-bumblebee gravity theory

“…The reason for that is the Event Horizon Telescope Collaboration's debut photograph of a black hole, which was first released in 2019 [61][62][63]. In fact, those pictures captured with the cutting-edge technology depict the shadow of M87 [64] and SgrA* [65,66], which are the supermassive black holes in the galaxy M87 and in the Milky Way Galaxy, respectively. But it was only during the last century that the first black hole's shadow was estimated.…”

Editorial to the Special Issue “Selected Papers from the 17th Russian Gravitational Conference—International Conference on Gravitation, Cosmology and Astrophysics (RUSGRAV-17)”

“…Articles [43,44] discuss a question of whether the object OJ 287 is a single supermassive black hole and the resonant effect for a Breit-Wheeler process in the field of a X-ray pulsar, respectively. Some other articles included in this Special Issue are devoted to relativistic effects in the orbital motion of S-stars at the galactic center [45], the resonant production of an ultrarelativistic electron-positron pair at the gamma quantum scattering [46], visible shapes of the black holes M87* and SgrA* [47], and the resonant effects in a photoproduction of ultrarelativistic electron-positron pairs on a nucleus [48]. Possible wormhole candidates in active galactic nuclei [49] and resonant effect of an annihilation channel in the interaction between an ultrarelativistic electron and a positron [50] are also discussed.…”