Speaker
Description
The existence of black holes is one of the most astonishing predictions of general theory of relativity. The Event Horizon Telescope (EHT) collaboration's latest observations, as well as the discovery of gravitational wave signals by the Laser-Interferometer Gravitational Wave-Observatory (LIGO) and Virgo corroborate the existence of these celestial objects. Despite the success, there are unresolved issues like existence of singularity in the theory and no observational evidence of dark matter. These two issues can be overcome by considering the regular black hole solution in scalar-tensor vector theory of gravity or MOG theory of gravity.
As a result of lensing, the black hole scatters photons with greater angular momentum from the source, delivering them to the distant observer, while photons with lower angular momentum fall into the black hole, creating a shadow zone and maybe a light ring. The black hole shadow that forms adjacent to the event horizon provides us with a rough idea of the underlying geometrical structure of horizons. Recent observation of black hole shadow of M87$*$ and SAG A$*$ by EHT collaboration has opened the new window to test alternative gravity theories. We have studied the details of the regular black hole in MOG theory and analysed the shadow structure for the same. These kind of black hole differs from Schwarzschild-Kerr black hole by a parameter $\beta$. A critical value of the parameter $\beta$ is found to be $\beta_{\rm crit}=0.4026$. The shadow for the horizonless dark compact object has been analysed for the static, spherically symmetric case and compared with M87 and Sgr A data. Shadow observables have been determined in the context of the regular black hole and used for obtaining the energy emission rate. The peak of the energy emission rate shifts to lower frequency for the increasing value of the parameter $\beta$.
| subhadipsau2@gmail.com | |
| Affiliation | Jhargram Raj College |
