Accretion flow in deformed Kerr spacetime: Spectral energy distributions from free-free emission. (arXiv:2308.12839v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Patra_S/0/1/0/all/0/1">Subhankar Patra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Majhi_B/0/1/0/all/0/1">Bibhas Ranjan Majhi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Das_S/0/1/0/all/0/1">Santabrata Das</a>
In this paper, we study the properties of accretion flow including its
spectral features in Johannsen and Psaltis (JP) non-Kerr spacetime. In doing
so, we numerically solve the governing equations that describe the flow motion
around the compact objects in a general relativistic framework, where spin
($a_{k}$) and deformation parameters ($varepsilon$) demonstrate the nature of
the central source, namely black hole (BH) or naked singularity (NS). With
this, we obtain all possible classes of global accretion solutions ($i. e.$, O,
A, W and I-type) by varying the energy ($E$) and angular momentum ($lambda$)
of the relativistic accretion flow, and examine the role of thermal
bremsstrahlung emission in studying the spectral energy distributions (SEDs) of
the accretion disc. We divide the parameter space in $lambda-E$ plane in terms
of the different classes of accretion solutions for BH and NS models. We
further calculate the disc luminosity ($L$) corresponding to these accretion
solutions, and observe that I-type solutions yield higher $L$ and SEDs than the
remaining types of solutions for both BH and NS models. For BH model, SEDs for
W and I-type solutions differ significantly from the results for O and A-type
solutions for low $E$ values. On the contrary, for NS model, SEDs for different
accretion solutions are identical in the whole parameter space of $lambda$ and
$E$. We also examine the effect of $varepsilon$ on the SEDs and observe that a
non-Kerr BH yields higher SEDs than the usual Kerr BH. Finally, for accretion
solutions of identical $E$ and $lambda$, we compare the SEDs obtained from BH
and NS models, and find that naked singularity objects produce more luminous
power spectra than the black holes.
In this paper, we study the properties of accretion flow including its
spectral features in Johannsen and Psaltis (JP) non-Kerr spacetime. In doing
so, we numerically solve the governing equations that describe the flow motion
around the compact objects in a general relativistic framework, where spin
($a_{k}$) and deformation parameters ($varepsilon$) demonstrate the nature of
the central source, namely black hole (BH) or naked singularity (NS). With
this, we obtain all possible classes of global accretion solutions ($i. e.$, O,
A, W and I-type) by varying the energy ($E$) and angular momentum ($lambda$)
of the relativistic accretion flow, and examine the role of thermal
bremsstrahlung emission in studying the spectral energy distributions (SEDs) of
the accretion disc. We divide the parameter space in $lambda-E$ plane in terms
of the different classes of accretion solutions for BH and NS models. We
further calculate the disc luminosity ($L$) corresponding to these accretion
solutions, and observe that I-type solutions yield higher $L$ and SEDs than the
remaining types of solutions for both BH and NS models. For BH model, SEDs for
W and I-type solutions differ significantly from the results for O and A-type
solutions for low $E$ values. On the contrary, for NS model, SEDs for different
accretion solutions are identical in the whole parameter space of $lambda$ and
$E$. We also examine the effect of $varepsilon$ on the SEDs and observe that a
non-Kerr BH yields higher SEDs than the usual Kerr BH. Finally, for accretion
solutions of identical $E$ and $lambda$, we compare the SEDs obtained from BH
and NS models, and find that naked singularity objects produce more luminous
power spectra than the black holes.
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