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The transonic phenomenon of black hole accretion and the existence of the photon sphere are the characteristics of strong gravitational fields near a black hole horizon. In this work, we study spherical accretion flow onto a general…

General Relativity and Quantum Cosmology · Physics 2021-01-01 Sen Yang , Cheng Liu , Tao Zhu , Li Zhao , Qiang Wu , Ke Yang , Mubasher Jamil

We perform 1D/2D/3D relativistic hydrodynamical simulations of accretion flows with low angular momentum, filling the gap between spherically symmetric Bondi accretion and disc-like accretion flows. Scenarios with different directional…

High Energy Astrophysical Phenomena · Physics 2017-09-07 Petra Suková , Szymon Charzyński , Agnieszka Janiuk

We investigate, within the framework of Quantum Field Theory in curved space, the correlations across the horizon of a black hole in order to highlight the particle-partner pair creation mechanism at the origin of Hawking radiation. The…

General Relativity and Quantum Cosmology · Physics 2022-02-17 Roberto Balbinot , Alessandro Fabbri

We investigate the backreaction equations for an acoustic black hole formed in a Laval nozzle under the assumption that the motion of the fluid is one-dimensional. The solution in the near-horizon region shows that as phonons are…

General Relativity and Quantum Cosmology · Physics 2009-11-10 R. Balbinot , S. Fagnocchi , A. Fabbri

We study the dynamical structure of a cooling dominated rotating accretion flow around a spinning black hole. We show that non-linear phenomena such as shock waves can be studied in terms of only three flow parameters, namely, the specific…

Astrophysics · Physics 2009-11-13 Santabrata Das , Sandip K. Chakrabarti

We present global solutions that describe advection-dominated accretion flows around black holes. The solutions are obtained by numerically solving a set of coupled ordinary differential equations corresponding to a steady axisymmetric…

Astrophysics · Physics 2009-10-28 Ramesh Narayan , Shoji Kato , Fumio Honma

In the present Master's thesis, I describe the research I conducted during my Master's program on the topic of analogue gravity. This line of research was initiated by Bill Unruh, who established an analogy between hydrodynamic flow with a…

General Relativity and Quantum Cosmology · Physics 2024-09-25 Chiara Coviello

We study the adiabatic accretion process of ordinary baryonic gas onto spherically symmetric black holes in Einstein-Maxwell-scalar theory, with two parameters $\alpha$ and $\beta$ in the coupling term. Especially, we demonstrate the range…

General Relativity and Quantum Cosmology · Physics 2022-04-27 Haiyuan Feng , Miao Li , Gui-Rong Liang , Rong-Jia Yang

We study the global solutions of slowly rotating accretion flows around the supermassive black hole in the nucleus of an elliptical galaxy. The velocity of accreted gas surrounding the black hole is initially subsonic and then falls onto…

High Energy Astrophysical Phenomena · Physics 2022-09-14 Razieh Ranjbar , Amin Mosallanezhad , Shahram Abbassi

Radiation emitted from an accretion disk around a massive black hole is a widely discussed model for the UV/soft X-ray excess emission observed in the spectra of many AGN. A self-consistent calculation of the structure and the emerging…

Astrophysics · Physics 2012-07-02 T. Doerrer , H. Riffert , R. Staubert , H. Ruder

For the first time, {\it all} available pseudo-Schwarzschild potentials are exhaustively used to investigate the possibility of shock formation in hydrodynamic, invicid, black hole accretion discs. It is shown that a significant region of…

Astrophysics · Physics 2009-11-07 Tapas Kumar Das

For axially symmetric accretion maintained in hydrostatic equilibrium along the vertical direction, we investigate how the characteristic features of the embedded acoustic geometry depends on the background Kerr metric, and how such…

High Energy Astrophysical Phenomena · Physics 2022-11-07 Susovan Maity , Pratik Tarafdar , Md. Arif Shaikh , Tapas K. Das

We examine the effects of thermal conduction on relativistic, magnetized, viscous, advective accretion flows around rotating black holes considering bremsstrahlung and synchrotron cooling processes. Assuming the toroidal component of…

High Energy Astrophysical Phenomena · Physics 2025-04-28 Monu Singh , Camelia Jana , Santabrata Das

We obtained steady solutions of optically thin, single temperature, magnetized black hole accretion disks assuming thermal bremsstrahlung cooling. Based on the results of 3D MHD simulations of accretion disks, we assumed that the magnetic…

Astrophysics · Physics 2015-06-24 H. Oda , M. Machida , K. E. Nakamura , R. Matsumoto

The topologies are obtained for accretion flows around black holes as the parameters, accretion rate and specific angular momentum are varied. Paczy{\'n}ski-Wiita pseudo-Newtonian potential is used to mimic the gravitational field of a…

Astrophysics · Physics 2009-09-29 Sivakumar G. Manickam

Traditionlly, gravitational wave emission from a coalescing binary system is computed using point mass approximations without considering any accretion disk. However, it is believed that in many of the galactic nuclei, there are…

Astrophysics · Physics 2007-05-23 Sandip K. Chakrabarti

In the present work, accretion onto a static spherically symmetric black hole in the hybrid metric-Palatini gravity is considered. The Novikov-Thorne model for a relativistic thin accretion disk is used. The energy flux, temperature…

General Relativity and Quantum Cosmology · Physics 2024-02-05 P. I. Dyadina , N. A. Avdeev

We investigate the global structure of the advection dominated accretion flow around a Schwarzschild black hole where the accretion disc is threaded by toroidal magnetic fields. We consider synchrotron radiative process as an effective…

High Energy Astrophysical Phenomena · Physics 2017-11-29 Biplob Sarkar , Santabrata Das , Samir Mandal

Multi-transonic accretion for a spinning black hole has been compared among different disc geometries within post Newtonian pseudo potential framework. The variation of stationary shock characteristics with black hole spin has been studied…

High Energy Astrophysical Phenomena · Physics 2023-08-04 Sonali Saha , Sharmistha Sen , Sankhasubhra Nag , Suparna Roychowdhury , Tapas K Das

We show that viscous, transonic accretion disks which start with sub-Keplerian angular momentum at the outer boundary reproduce the features of the so-called thick, thin, slim and other accretion disk models depending upon the accretion…

Astrophysics · Physics 2007-05-23 Sandip K. Chakrabarti