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Matter falling onto black holes is hot, fully ionized and has to be necessarily transonic. Since the electrons are responsible for radiative cooling via processes like synchrotron, bremsstrahlung and inverse-Compton, therefore the electron…

High Energy Astrophysical Phenomena · Physics 2019-02-20 Shilpa Sarkar , Indranil Chattopadhyay

The structure of the inner region of an advection-dominated accretion disk around a nonrotating black hole is explored by applying asymptotic analysis in the region just outside the event horizon. We assume that the viscous transport is…

Astrophysics · Physics 2009-11-07 Peter A. Becker , Truong Le

Despite the fact that the Schwarzschild and Kerr solutions for the Einstein equations, when written in standard Schwarzschild and Boyer-Lindquist coordinates, present coordinate singularities, all numerical studies of accretion flows onto…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Philippos Papadopoulos , Jose A. Font

An accretion flow is necessarily transonic around a black hole. However, around a neutron star it may or may not be transonic, depending on the inner disk boundary conditions influenced by the neutron star. I will discuss various transonic…

Astrophysics · Physics 2009-11-13 Banibrata Mukhopadhyay

We present the critical conditions for hot trans-fast magnetohydrodynamical (MHD) flows in a stationary and axisymmetric black-hole magnetosphere. To accrete onto the black hole, the MHD flow injected from a plasma source with low velocity…

Astrophysics · Physics 2009-11-07 Masaaki Takahashi

We apply the theory of algebraic polynomials to analytically study the transonic properties of general relativistic hydrodynamic axisymmetric accretion onto non-rotating astrophysical black holes. For such accretion phenomena, the conserved…

General Relativity and Quantum Cosmology · Physics 2012-04-05 Shilpi Agarwal , Tapas K. Das , Rukmini Dey , Sankhasubhra Nag

Low-angular-momentum, axisymmetric, inviscid accretion flows onto a black hole have been studied using the vertical equilibrium disc model, considering multiple pseudo-Schwarzschild potentials and two thermodynamic equations of state. A…

High Energy Astrophysical Phenomena · Physics 2026-05-13 Ripon Sk , Sangita Chatterjee , Sankhasubhra Nag

This work introduces a novel formalism to investigate the role of the spin of astrophysical black holes in determining the behaviour of matter falling onto such accretors. Equations describing the general relativistic hydrodynamic accretion…

High Energy Astrophysical Phenomena · Physics 2009-02-25 Paramita Barai , Ipsita Chakraborty , Tapas K Das , Paul J Wiita

We present results of numerical simulation of inviscid thick accretion disks and wind flows around black holes. We use Smoothed Particle Hydrodynamics (SPH) technique for this purpose. Formation of thick disks are found to be preceded by…

Astrophysics · Physics 2009-10-22 Diego Molteni , G. Lanzafame , S. K. Chakrabarti

We introduce a novel formalism to investigate the role of the spin angular momentum of astrophysical black holes in influencing the behaviour of low angular momentum general relativistic accretion. We propose a metric independent analysis…

We study the two-temperature magnetized advective accretion flow around the Kerr black holes. During accretion, ions are heated up due to viscous dissipation, and when Coulomb coupling becomes effective, they transfer a part of their energy…

High Energy Astrophysical Phenomena · Physics 2020-07-01 Indu K. Dihingia , Santabrata Das , Geethu Prabhakar , Samir Mandal

Depending on the astrophysical source and its environment, the accretion flows can exhibit a variety of behaviors and characteristics in accordance with the type of solutions. We study low-angular-momentum accretion flows onto black holes…

High Energy Astrophysical Phenomena · Physics 2025-08-01 Indu K. Dihingia , Akhil Uniyal , Yosuke Mizuno

The equations governing general relativistic, spherically symmetric, hydrodynamic accretion of polytropic fluid onto black holes are solved in Schwarzschild metric to investigate some of the transonic properties of the flow. Only stationary…

Astrophysics · Physics 2008-11-26 Tapas Kumar Das

Standard accretion disk theory is formulated which is based on the local heat balance. The energy produced by a turbulent viscous heating is supposed to be emitted to the sides of the disc. Sources of turbulence in the accretion disc are…

Astrophysics · Physics 2007-05-23 G. S. Bisnovatyi-Kogan

We present a systematic numerical study of two-dimensional axisymmetric accretion flows around black holes. The flows have no radiative cooling and are treated in the framework of the hydrodynamical approximation. The models calculated in…

Astrophysics · Physics 2016-08-30 Igor V. Igumenshchev , Marek A. Abramowicz

We propose a novel approach to the investigation of how black hole spin influences the behavior of astrophysical accretion. We examine the terminal behavior of general relativistic, multi-transonic, hydrodynamic advective accretion in the…

Astrophysics · Physics 2009-11-10 Paramita Barai , Tapas Kumar Das , Paul J. Wiita

We explore the global structure of the accretion flow around a Schwarzschild black hole where the accretion disc is threaded by toroidal magnetic fields. The accretion flow is optically thin and advection dominated. Synchrotron radiation is…

High Energy Astrophysical Phenomena · Physics 2018-03-14 Biplob Sarkar , Santabrata Das

The present work addresses an axisymmetrically accreting black hole system from three perspectives: the astrophysical, the dynamical systems, and the emergent gravity standpoint. Steady-state equations governing low angular momentum axially…

High Energy Astrophysical Phenomena · Physics 2026-05-07 Kalyanbrata Pal , Souvik Ghose , Ripon Sk , Arpan Krishna Mitra , Tapas K. Das

Using mathematical formalism borrowed from dynamical systems theory, a complete analytical investigation of the critical behaviour of the stationary flow configuration for the low angular momentum axisymmetric black hole accretion provides…

High Energy Astrophysical Phenomena · Physics 2015-05-20 S. Nag , S. Acharya , A. K. Ray , Tapas K. Das

We investigate the transonic accretion flow in the spacetime of a supermassive black hole (BH) coupled to an anisotropic dark matter fluid, as proposed by Cardoso {\it et al}. We essentially compare the accretion properties of the Cardoso…

High Energy Astrophysical Phenomena · Physics 2025-07-11 Subhankar Patra , Bibhas Ranjan Majhi