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We compute the effects of the centrifugal pressure supported shock waves on the emitted spectrum from an accretion disk primarily consisting of low angular momentum matter. Electrons are very efficiently accelerated by the accretion shock…

Astrophysics · Physics 2009-11-10 Samir Mandal , Sandip K. Chakrabarti

We study the properties of the shock waves for a viscous accretion flow having low angular momentum in presence of synchrotron cooling. We present all possible accretion solutions in terms of flow parameters. We identify the region of the…

Astrophysics · Physics 2016-11-15 Santabrata Das , Sandip K. Chakrabarti

Low angular momentum accretion flows can have standing and oscillating shock waves. We study the region of the parameter space in which multiple sonic points occur in viscous flows in presence of various cooling effects such as…

Astrophysics · Physics 2016-08-30 Santabrata Das , Sandip K. Chakrabarti

We study the properties of two-temperature accretion flow around a non-rotating black hole in presence of various dissipative processes where pseudo-Newtonian potential is adopted to mimic the effect of general relativity. The flow…

High Energy Astrophysical Phenomena · Physics 2018-02-14 Indu K. Dihingia , Santabrata Das , Samir Mandal

Accretion flows having positive specific energy are known to produce outflows and winds which escape to a large distance. According to Two Component Advective Flow (TCAF) model, centrifugal pressure dominated region of the flow just outside…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Santanu Mondal , Sandip K Chakrabarti , Dipak Debnath

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

We study the spectral properties of a low angular momentum flow as a function of the shock strength, compression ratio, accretion rate and flow geometry. In the absence of a satisfactory description of magnetic fields inside the advective…

Astrophysics · Physics 2009-11-10 Samir Mandal , Sandip K. Chakrabarti

Centrifugal barrier supported boundary layer (CENBOL) of a black hole affects the spectrum exactly in the same way the boundary layer of a neutron star does. The CENBOL is produced due to standing or oscillating shock waves and these shocks…

Astrophysics · Physics 2007-05-23 Samir Mandal , Sandip K. Chakrabarti

The existence of hot, two-temperature accretion flows is essential to the recent discussions of the low luminosity, hard X-ray emission from accreting neutron stars and black holes in Galactic binaries and massive black holes in low…

Astrophysics · Physics 2009-10-31 Jongmann Yang , Insu Yi

Steady-state advective accretion flows in the presence of thermal conduction are studied. All three components of velocity in a spherical coordinates are considered and the flow displays both inflowing and outflowing regions according to…

Astrophysics of Galaxies · Physics 2015-06-17 Fazeleh Khajenabi , Mohsen Shadmehri

Recent studies show that accretion flows around weakly magnetic Neutron Stars undergo multiple shocks, before reaching the surface of the star, which contribute to the spectral and timing variabilities observed in the X-Rays. Here, we…

High Energy Astrophysical Phenomena · Physics 2021-01-01 Ayan Bhattacharjee , Sandip K. Chakrabarti

We perform two-dimensional simulations to study how the wind strength changes with accretion rate. We take into account bremsstrahlung, synchrotron radiation and the Comptonization. We find that when the accretion rate is low, radiative…

High Energy Astrophysical Phenomena · Physics 2017-12-20 De-Fu Bu , Zhao-Ming Gan

We carry out the first robust numerical simulation of accretion flows on a weakly magnetized neutron star using Smoothed Particle Hydrodynamics (SPH). We follow the Two-Component Advective Flow (TCAF) paradigm for black holes, and focus…

High Energy Astrophysical Phenomena · Physics 2019-03-20 Ayan Bhattacharjee , Sandip K. Chakrabarti

The structure of the hot downstream region below a radiative accretion shock, such as that of an accreting compact object, may oscillate due to a global thermal instability. The oscillatory behaviour depends on the functional forms of the…

Astrophysics · Physics 2009-10-31 Curtis J. Saxton , Kinwah Wu

Non-radiating, advection-dominated, accretion flows are convectively unstable. We calculate the two-dimensional (r-theta) structure of such flows assuming that (1) convection transports angular momentum inwards, opposite to normal viscosity…

Astrophysics · Physics 2009-10-31 Eliot Quataert , Andrei Gruzinov

We investigate two-temperature accretion flows onto strongly magnetized compact stars. Matter is accreted in the form of an accretion disc upto the disc radius ($r_{\rm d}$), where, the magnetic pressure exceeds both the gas and ram…

High Energy Astrophysical Phenomena · Physics 2023-04-19 Shilpa Sarkar , Kuldeep Singh , Indranil Chattopadhyay , Philippe Laurent

The temperatures of electrons and ions in the post-shock accretion region of a magnetic cataclysmic variable (mCV) will be equal at sufficiently high mass flow rates or for sufficiently weak magnetic fields. At lower mass flow rates or in…

Astrophysics · Physics 2009-11-13 Gordon E. Sarty , Curtis J. Saxton , Kinwah Wu

We have solved the one-dimensional stationary two-fluid hydrodynamic equations for post-shock flows on accreting magnetic white dwarfs simultaneous with the fully frequency and angle-dependent radiative transfer for cyclotron radiation and…

Astrophysics · Physics 2009-11-06 A. Fischer , K. Beuermann

Radiatively inefficient, hot accretion flows are widely considered as a relevant accretion mode in low-luminosity AGNs. We study spectral formation in such flows using a refined model with a fully general relativistic description of both…

High Energy Astrophysical Phenomena · Physics 2014-04-07 Andrzej Niedzwiecki , Fu-Guo Xie , Agnieszka Stepnik

We quantify the effects of electron thermal conduction on the properties of hot accretion flows, under the assumption of spherical symmetry. Electron heat conduction is important for low accretion rate systems where the electron cooling…

Astrophysics · Physics 2011-02-11 Bryan M. Johnson , Eliot Quataert
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