Dynamical properties of oscillating, viscous, transonic accretion disks around black holes

Fuente: arXiv
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Main Authors: Debnath, Sanjit, Chattopadhyay, Indranil, Joshi, Raj Kishor, Laurent, Philippe, Tripathi, Priyesh Kumar, Khan, M. Saleem
Format: Preprint
Published: 2025
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author Debnath, Sanjit
Chattopadhyay, Indranil
Joshi, Raj Kishor
Laurent, Philippe
Tripathi, Priyesh Kumar
Khan, M. Saleem
author_facet Debnath, Sanjit
Chattopadhyay, Indranil
Joshi, Raj Kishor
Laurent, Philippe
Tripathi, Priyesh Kumar
Khan, M. Saleem
contents We investigate the time evolution of sub-Keplerian transonic accretion flow onto a non-rotating black hole using axisymmetric viscous hydrodynamic simulations. We simulate the accretion flow using boundary values from semi-analytical analysis and set up three different models. Two of the models do not predict accretion shocks from the semi-analytic analysis, while one of them does. We also consider radiative cooling along with viscosity in the simulation. Our two-dimensional simulation deviated from the one-dimensional semi-analytical solution and admitted shocks in all three models. Viscous dissipation tends to push the shock front outward, and radiative cooling will push it in. Additionally, gravity is attractive. Depending on the competing strengths of all three processes, it may trigger shock oscillation. Different rates of angular-momentum transport in various layers may trigger eddies, which will enhance the shock oscillation. We show that any simple power law cannot approximate these solutions. We find that hot and higher angular-momentum flow requires higher viscosity to produce oscillatory shocks. From the temporal variation of the luminosity, shock oscillations generate QPOs in the range of sub-Hertz to a few Hertz frequencies if a ten solar mass black hole is assumed.
format Preprint
id arxiv_https___arxiv_org_abs_2509_19934
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dynamical properties of oscillating, viscous, transonic accretion disks around black holes
Debnath, Sanjit
Chattopadhyay, Indranil
Joshi, Raj Kishor
Laurent, Philippe
Tripathi, Priyesh Kumar
Khan, M. Saleem
High Energy Astrophysical Phenomena
We investigate the time evolution of sub-Keplerian transonic accretion flow onto a non-rotating black hole using axisymmetric viscous hydrodynamic simulations. We simulate the accretion flow using boundary values from semi-analytical analysis and set up three different models. Two of the models do not predict accretion shocks from the semi-analytic analysis, while one of them does. We also consider radiative cooling along with viscosity in the simulation. Our two-dimensional simulation deviated from the one-dimensional semi-analytical solution and admitted shocks in all three models. Viscous dissipation tends to push the shock front outward, and radiative cooling will push it in. Additionally, gravity is attractive. Depending on the competing strengths of all three processes, it may trigger shock oscillation. Different rates of angular-momentum transport in various layers may trigger eddies, which will enhance the shock oscillation. We show that any simple power law cannot approximate these solutions. We find that hot and higher angular-momentum flow requires higher viscosity to produce oscillatory shocks. From the temporal variation of the luminosity, shock oscillations generate QPOs in the range of sub-Hertz to a few Hertz frequencies if a ten solar mass black hole is assumed.
title Dynamical properties of oscillating, viscous, transonic accretion disks around black holes
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2509.19934