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A novel methodology to obtain global transonic solutions around compact objects is reported here. A unified methodology to obtain accretion as well as wind solutions around these objects has been presented. Flows around compact objects are…

High Energy Astrophysical Phenomena · Physics 2025-06-02 Shilpa Sarkar

Accretion disks are three-dimensional, turbulent, often self-gravitating, magnetohydrodynamic flows, which can be modeled in detail with numerical simulations. In this paper, we present a new algorithm that is based on a spectral…

Astrophysics · Physics 2009-07-22 Chi-kwan Chan , Dimitrios Psaltis , Feryal Ozel

The thermomagnetic convection of magnetic fluids in a cylindrical geometry subjected to a homogeneous magnetic field is studied. The study is motivated by a novel thermal instability [W. Luo et al., Phys. Rev. Lett. 82, 4134 (1999)]. As…

Pattern Formation and Solitons · Physics 2009-11-07 Adrian Lange

Two-dimensional numerical simulations of an accretion flow in a close binary system are performed by solving the Euler equations with radiative transfer. In the present study, the specific heat ratio is assumed to be constant while…

Astrophysics · Physics 2009-11-07 Jun'ichi Sato , Keisuke Sawada , Naofumi Ohnishi

Based on no-outflow assumption, we investigate steady state, axisymmetric, optically thin accretion flows in spherical coordinates. By comparing the vertically integrated advective cooling rate with the viscous heating rate, we find that…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Wei-Min Gu

We consider hot, two-temperature, viscous accretion onto a rotating, unmagnetized neutron star. We assume Coulomb coupling betweenthe protons and electrons, and free-free cooling from the electrons. We show that the accretion flow has an…

Astrophysics · Physics 2009-10-31 Mikhail V. Medvedev , Ramesh Narayan

By taking into account the effect of toroidal magnetic field and its correspond heating, we determine the thickness of advection-dominated accretion flows. We consider an axisymetric, rotating, steady viscous-resistive, magnetized accretion…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Maryam Samadi , Shahram Abbassi , Mahdi Khajavi

We show that the differential rotation profile of the solar convection zone, apart from inner and outer boundary layers, can be reproduced with great accu- racy if the isorotation contours correspond to characteristics of the thermal wind…

Solar and Stellar Astrophysics · Physics 2015-05-13 S. A. Balbus , J. Bonart , H. N. Latter , N. O. Weiss

Radiatively inefficient accretion flows (RIAFs) are common feature of low-luminosity accretion flows, including quiescent states of X-ray binaries and low-lunimosity active galactic nuclei. Thermally driven winds are expected from such hot…

High Energy Astrophysical Phenomena · Physics 2015-05-13 Ryoji Kawabata , Shin Mineshige

Observations of the hot gas surrounding Sgr A* and a few other nearby galactic nuclei imply electron and proton mean free paths comparable to the gas capture radius: hot accretion likely proceeds under weakly-collisional conditions in these…

Astrophysics · Physics 2007-05-23 Kristen Menou

We consider axisymmetric viscous accretion flows where a fraction f of the viscously dissipated energy is advected with the accreting gas as stored entropy and a fraction 1-f is radiated. When f is small (i.e. very little advection), our…

Astrophysics · Physics 2009-10-22 Ramesh Narayan , Insu Yi

We generalize a recent method for computing optimal 2D convection cooling flows in a horizontal layer to a wide range of geometries, including those relevant for technological applications. We write the problem in a conformal pair of…

Fluid Dynamics · Physics 2017-04-05 Silas Alben

We present steady-state solutions for a one-dimensional, magnetically-driven accretion disk wind model based on magnetohydrodynamic equations. We assume a geometrically thin, gas-pressure-dominated accretion disk, incorporating both…

High Energy Astrophysical Phenomena · Physics 2025-01-23 Mageshwaran Tamilan , Kimitake Hayasaki , Takeru K. Suzuki

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

Recently, Medvedev & Narayan (2001) discovered a new type of accretion flow, a hot settling flow around a rapidly rotating neutron star. The flow is cooling-dominated and energetically similar to the Shapiro, Lightman, & Eardley (1976, SLE)…

Astrophysics · Physics 2007-05-23 Mikhail V. Medvedev , Ramesh Narayan

We consider height-integrated equations of an advection-dominated accretion flow (ADAF), assuming that there is no mass outflow. We include convection through a mixing length formalism. We seek self-similar solutions in which the rotational…

Astrophysics · Physics 2009-10-31 Ramesh Narayan , Igor V. Igumenshchev , Marek A. Abramowicz

Hot, tenuous advection-dominated accretion flows around black holes are ideal sites for the Fermi acceleration of relativistic particles at standing shock waves in the accretion disc. Previous work has demonstrated that the…

High Energy Astrophysical Phenomena · Physics 2020-02-17 Jason P. Lee , Peter A. Becker

We present the effect of a hydrodynamical wind on the structure and the surface temperature of a vertically self-gravitating magnetized ADAFs using self-similar solutions. Also a model for an axisymmetric, steady-state, vertically…

High Energy Astrophysical Phenomena · Physics 2016-03-30 Maryam Ghasemnezhad , Shahram Abbassi

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

Spherical (nonrotating) accretion flows with small-scale magnetic fields have been investigated using three-dimensional, time-dependent MHD simulations. These simulations have been designed to model high-resolution (quasi) steady accretion…

Astrophysics · Physics 2008-11-26 Igor V. Igumenshchev