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Related papers: Modeling Dipolar Post-Shock Accretion Columns for …

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In order to confirm the anisotropic effect of resonance photons in hot accretion columns on white dwarfs in magnetic cataclysmic variables, proposed by Terada etal (2001), systematic studies with ASCA of 7 polars and 12 intermediate polars…

Astrophysics · Physics 2015-06-24 Yukikatsu Terada , Manabu Ishida , Kazuo Makishima

We describe a geometric model for synchrotron and synchrotron self-Compton (SSC) radiation from blazar jets, involving multiple emission zones with turbulent magnetic fields and fully self-consistent seed photon mixing for SSC. Including…

High Energy Astrophysical Phenomena · Physics 2020-01-08 A. L. Peirson , R. W. Romani

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

We explore conditions and structure of accretion disks in short-period Cata- clysmic Variables (CVs), which have evolved beyond the period minimum. We show that accretion discs in systems with extreme mass ratios grow up to the size of…

Solar and Stellar Astrophysics · Physics 2010-10-04 Sergey Zharikov , Gaghik Tovmassian , Andres Aviles , Mauricio Tapia , Miguel Roth

We performed geometric pulsar light curve modeling using static, retarded vacuum, and offset polar cap (PC) dipole $B$-fields (the latter is characterized by a parameter $\epsilon$), in conjunction with standard two-pole caustic (TPC) and…

High Energy Astrophysical Phenomena · Physics 2017-01-12 Monica Barnard , Christo Venter , Alice K. Harding

We perform 2D axisymmetric radiative relativistic MHD simulations of radiation pressure supported neutron star accretion columns in split-monopole magnetic fields. The accretion columns exhibit quasi-periodic oscillations, which manifest in…

High Energy Astrophysical Phenomena · Physics 2023-02-01 Lizhong Zhang , Omer Blaes , Yan-Fei Jiang

The disc instability model (DIM) has been very successful in explaining the dwarf nova outbursts observed in cataclysmic variables. When, as in intermediate polars (IP), the accreting white dwarf is magnetized, the disc is truncated at the…

Solar and Stellar Astrophysics · Physics 2017-06-28 J. -M. Hameury , J. -P. Lasota

We present a grid of models of accreting brown dwarf systems with circumstellar discs. The calculations involve a self-consistent solution of both vertical hydrostatic and radiative equilibrium along with a sophisticated treatment of dust…

Solar and Stellar Astrophysics · Physics 2015-05-19 Nathan Mayne , Tim Harries

Metals in the photospheres of white dwarfs with Teff between 12,000 and 25,000 K should gravitationally settle out of these atmospheres in 1-2 weeks. Temporal variations in the line strengths of these metals could provide a direct…

Astrophysics · Physics 2011-02-11 Ted von Hippel , Susan E. Thompson

A number of cool white dwarfs with metal traces, of spectral types DAZ, DBZ, and DZ have been found to exhibit infrared excess radiation due to circumstellar dust. The origin of this dust is possibly a tidally disrupted asteroid that formed…

Solar and Stellar Astrophysics · Physics 2015-05-13 D. Koester

Hydrogen atmosphere white dwarfs with metal lines, so-called DAZs, require external accretion of material to explain the presence of weak metal line absorption in their photospheres. The source of this material is currently unknown, but…

Astrophysics · Physics 2009-06-23 J. H. Debes , S. Sigurdsson , B. Hansen

Despite the fact that pulsars have been observed for almost half a century, many questions have remained unanswered. We use the analysis of X-ray observations in order to study the polar cap region of radio pulsars. The size of the hot…

High Energy Astrophysical Phenomena · Physics 2013-04-19 Andrzej Szary

We have calculated the structures and the emergent spectra of stationary, geometrically thin accretion disks around 100 and 1000 M_sun black holes in both the Schwarzschild and extreme Kerr metrics. Equations of radiative transfer,…

Astrophysics · Physics 2009-11-10 Y. Hui , J. H. Krolik , I. Hubeny

We present relativistic, radiation magnetohydrodynamic simulations of supercritical neutron star accretion columns in Cartesian geometry, including temperature-dependent, polarization-averaged Rosseland mean opacities accounting for…

High Energy Astrophysical Phenomena · Physics 2023-07-26 Xin Sheng , Lizhong Zhang , Omer Blaes , Yan-Fei Jiang

The main purpose of this paper is to obtain analytical solutions for radiative transfer equations related to the vertical structure of accretion discs with finite optical depth. In the non-gray atmosphere, we employ the optical-depth…

High Energy Astrophysical Phenomena · Physics 2020-06-24 Maryam Samadi , Fahimeh Habibi , Shahram Abbassi

We have developed a 3D computer model of polars which includes the accretion stream, the accretion column, the secondary star, and the white dwarf. Each component is represented by a fine grid of surface elements. With brightness values…

Astrophysics · Physics 2007-05-23 Jens Kube , Boris T. Gaensicke , Klaus Beuermann

It has long been thought that black hole accretion flows are driven by magnetohydrodynamic (MHD) turbulence, and there are now many general relativistic global simulations illustrating the dynamics of this process. However, many challenges…

High Energy Astrophysical Phenomena · Physics 2026-03-11 Chris Nagele , Julian H. Krolik , Rongrong Liu , Brooks E. Kinch , Jeremy D. Schnittman

We propose a novel theoretical model to describe a physical identity of the soft X-ray excess, ubiquitously detected in many Seyfert galaxies, by considering a steady-state, axisymmetric plasma accretion within the innermost stable circular…

High Energy Astrophysical Phenomena · Physics 2016-08-17 Keigo Fukumura , Douglas Hendry , Peter Clark , Francesco Tombesi , Masaaki Takahashi

We consider a method for obtaining information on polarization of astronomical objects radiation at diffraction limited resolution - differential speckle polarimetry. As an observable we propose to use averaged cross spectrum of two…

Instrumentation and Methods for Astrophysics · Physics 2015-06-12 Boris Safonov

We present the black hole accretion code (BHAC), a new multidimensional general-relativistic magnetohydrodynamics module for the MPI-AMRVAC framework. BHAC has been designed to solve the equations of ideal general-relativistic…

General Relativity and Quantum Cosmology · Physics 2017-06-20 Oliver Porth , Hector Olivares , Yosuke Mizuno , Ziri Younsi , Luciano Rezzolla , Monika Moscibrodzka , Heino Falcke , Michael Kramer