General relativistic numerical simulation of sub-Keplerian transonic accretion flows on to black holes: Schwarzschild space–time

Kim, Jin-Ho; Garain, Sudip K.; Balsara, Dinshaw S.; Chakrabarti, Sandip K.

doi:10.1093/mnras/stx1986

Cited by 12 publications

(8 citation statements)

References 54 publications

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“…Numerical study also supports this view as the accretion flow enters in to the black hole supersonically (Chakrabarti & Molteni 1995;Lanzafame et al 1998;? ;Giri & Chakrabarti 2013;Suková & Janiuk 2015;Kim et al 2017). Moreover, the above assertions are also endorsed observationally for several black hole candidates as well (Smith et al 2001(Smith et al , 2002Wu et al 2002;Yu et al 2004;Smith et al 2007;Cambier & Smith 2013;Debnath et al 2014;Iyer et al 2015;Nandi et al 2018).…”

Section: Introductionmentioning

confidence: 68%

Accretion-ejection in rotating black holes: a model for ‘outliers’ track of radio-X-ray correlation in X-ray binaries

Aktar

Nandi

Das

2019

Astrophys Space Sci

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We study the global accretion-ejection solutions around a rotating black hole considering three widely accepted pseudo-Kerr potentials that satisfactorily mimic the space-time geometry of rotating black holes. We find that all the pseudo potentials provide standing shock solutions for large range of flow parameters. We identify the effective region of the shock parameter space spanned by energy (E in ) and angular momentum (λ in ) measured at the inner critical point (x in ) and find that the possibility of shock formation becomes feeble when the viscosity parameter (α) is increased. In addition, we find that shock parameter space also depends on the adiabatic index (γ) of the flow and the shock formation continues to take place for a wide range of γ as 1.5 ≤ γ ≤ 4/3. For all the pseudo potentials, we calculate the critical viscosity parameter (α cri shock ) beyond which standing shock ceases to exist and compare them as function of black hole spin (a k ). We observe that all the pseudo potentials under consideration are qualitatively similar as far as the standing shocks are concerned, however, they differ both qualitatively and quantitatively from each other for rapidly rotating black holes. Further, we compute the mass loss from the disc using all three pseudo potentials and find that the maximum mass outflow rate (R maẋ m ) weakly depends on the black hole spin. To validate our model, we calculate the maximum jet kinetic power using the accretion-ejection formalism and compare it with the radio jet power of low-hard state of the black hole X-ray binaries (hereafter XRBs). The outcome of our results indicate that XRBs along the 'outliers' track might be rapidly rotating.

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Section: Introductionmentioning

confidence: 68%

Accretion-ejection in rotating black holes: a model for ‘outliers’ track of radio-X-ray correlation in X-ray binaries

Aktar

Nandi

Das

2019

Astrophys Space Sci

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“…To show the effects of dragging of frames due to spin of the black hole, we run the same case twice: For the Kerr (a = 0.95) and the Schwarzschild (a = 0) geometries and then take the difference in density distribution in the two cases. We injected matter with radial velocity 0.02288 and sound speed 0.08053 at rout = 200 (Kim et al 2017). However, for Schwarzschild black hole case, the inner boundary is placed at rin = 2.1 and for Kerr black hole, rin = 1.5.…”

Section: Two Dimensional Bondi Accretion Flowmentioning

confidence: 99%

General relativistic numerical simulation of sub-Keplerian transonic accretion flows on to rotating black holes: Kerr space–time

Kim

Garain

Chakrabarti

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We study time evolution of sub-Keplerian transonic accretion flows onto black holes using a general relativistic numerical simulation code. We perform simulations around the black holes having non-zero rotation. We first compare one-dimensional simulation results with theoretical results and validate the performance of our code. Next, we present results of axisymmetric, two-dimensional simulation of advective flows. In the literature, there is no solution which describes steady shock solutions in two dimensions. However, our simulations produce these centrifugal force supported steady shock waves even in presence of strong dragging of inertial frames. Since the post-shock region could be hot and upscatter photons through Comptonization, these shock would put imprints on the spectra. Thus, our solutions, which represent truly new results, could be useful to measure spins through radiation spectrum of accreting Kerr black holes.

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“…All the above-mentioned simulation works addressed the accretion flow behavior around a non-rotating black hole by relying on pseudo-Newtonian potential. Recently, general relativistic highresolution shock-capturing simulation code was used to study the scenario in Schwarzschild (Kim et al 2017) and Kerr (Kim et al 2019) space-time which further established the formation of a standing shock in hydrodynamic (HD) flow around a non-rotating as well as rotating black hole in full general relativistic treatment. However, till now there has been only one work taking into account different magnitudes of magnetic field strength in such flows in the presence of standing shocks (Okuda et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Effects of resistivity on standing shocks in low angular momentum flows around black holes

Singh

Okuda

Aktar

2021

Res. Astron. Astrophys.

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We study two-dimensional low angular momentum flow around a black hole using the resistive magnetohydrodynamic module of PLUTO code. Simulations have been performed for the flows with parameters of specific angular momentum, specific energy and magnetic field which may be expected for the flow around Sgr A*. For flows with lower resistivity η = 10−6 and 0.01, the luminosity and shock location on the equator vary quasi-periodically. The power density spectra of luminosity variation show peak frequencies which correspond to the periods of 5 × 105, 1.4 × 105 and 5 × 104 s. These quasi-periodic oscillations (QPOs) occur due to interaction between the outer oscillating standing shock and the inner weak shocks occurring at the innermost hot blob. While for cases with higher resistivity η = 0.1 and 1.0, the high resistivity considerably suppresses the magnetic activity such as MHD turbulence and the flows tend to be steady and symmetric with respect to the equator. The steady standing shock is formed more outward compared with the hydrodynamical flow. The low angular momentum flow model with the above flow parameters and with low resistivity has a possibility to explain long-term flares of Sgr A* with frequencies ∼ one per day and ∼ 5 – 10 days in the latest observations by Chandra, Swift and XMM-Newton monitoring of Sgr A*.

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General relativistic numerical simulation of sub-Keplerian transonic accretion flows on to black holes: Schwarzschild space–time

Cited by 12 publications

References 54 publications

Accretion-ejection in rotating black holes: a model for ‘outliers’ track of radio-X-ray correlation in X-ray binaries

Accretion-ejection in rotating black holes: a model for ‘outliers’ track of radio-X-ray correlation in X-ray binaries

General relativistic numerical simulation of sub-Keplerian transonic accretion flows on to rotating black holes: Kerr space–time

Effects of resistivity on standing shocks in low angular momentum flows around black holes

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