1,125 research outputs found
Rotating black hole in Rastall theory
Rotating black hole solutions in theories of modified gravity are important
as they offer an arena to test these theories through astrophysical
observation. The non-rotating black hole can be hardly tested since the black
hole spin is very important in any astrophysical process. We present rotating
counterpart of a recently obtained spherically symmetric exact black hole
solution surrounded by perfect fluid in the context of Rastall theory, viz,
rotating Rastall black hole that generalize the Kerr-Newman black hole
solution. In turn, we analyze the specific cases of the Kerr-Newman black holes
surrounded by matter like dust and quintessence fields. Interestingly, for a
set of parameters and a chosen surrounding field, there exists a critical
rotation parameter (), which corresponds to an extremal black hole
with degenerate horizons, while for , it describes a non-extremal
black hole with Cauchy and event horizons, and no black hole for with
value is also influenced by these parameters. We also discuss the
thermodynamical quantities associated with rotating Rastall black hole, and
analyze the particle motion with the behavior of effective potential.Comment: 26 pages, 8 figures. Matched with the published versio
Accretion onto a noncommutative geometry inspired black hole
The spherically symmetric accretion onto a noncommutative (NC) inspired
Schwarzschild black hole is treated for a polytropic fluid. The critical
accretion rate , sonic speed and other flow parameters are
generalised for the NC inspired black hole and compared with the results
obtained for the standard Schwarzschild black holes. We also derive explicit
expressions for gas compression ratios and temperature profiles below the
accretion radius and at the event horizon. This analysis is a generalisation of
Michel's solution to the NC geometry. Owing to the NC corrected black hole, the
accretion flow parameters have also been modified. It turns out that is still achievable but seems to be substantially
decreased due to NC effects, that in turn does affect the accretion process.Comment: Published in EPJ
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