278 research outputs found
Photon regions, shadow observables and constraints from M87* of a charged rotating black hole
Inspired by the observations of supermassive black hole M87* in \emph{Event
Horizon Telescope }(EHT) experiment, a remarkable surge in black hole physics
is to use the black hole shadow's observables to distinguish general relativity
(GR) and modified theories of gravity (MoG), which could also help to disclose
the astrophysical nature of the center black hole in EHT observation. In this
paper, we shall extensively carry out the study of a charged rotating black
hole in conformal gravity, in which the term related with the charge has
different falloffs from the usual Kerr-Newman (KN) black hole. We investigate
the spacetime properties including the horizons, ergospheres and the photon
regions; afterward, we show the boundary of black hole shadow and investigate
its characterized observables. The features closely depend on the spin and
charge parameters, which are compared with those in Kerr and KN black holes.
Then presupposing the M87* a charged rotating black hole in conformal gravity,
we also constrain the black hole parameters via the observation constraints
from EHT experiment. We find that the constraints on the inferred circularity
deviation, , and on the shadow axial ratio, , for the M87* black hole are satisfied for the entire parameter
space of the charged rotating black hole in conformal gravity. However, the
shadow angular diameter will give upper bound on
the parameter space. Our findings indicate that the current charged rotating
black hole in conformal gravity could be a candidate for astrophysical black
holes. Moreover, the EHT observation on the axial ratio may help us to
distinguish Kerr black hole and the current charged rotating black hole in
conformal gravity in some parameter space.Comment: references adde
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