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Indirect imaging problems in biomedical optics generally require repeated evaluation of forward models of radiative transport, for which Monte Carlo is accurate yet computationally costly. We develop a novel approach to reduce this…

Computational Physics · Physics 2020-07-10 Callum M. Macdonald , Simon Arridge , Samuel Powell

Hot, diffuse, relativistic plasmas such as sub-Eddington black hole accretion flows are expected to be collisionless, yet are commonly modeled as a fluid using ideal general relativistic magnetohydrodynamics (GRMHD). Dissipative effects…

Instrumentation and Methods for Astrophysics · Physics 2017-03-15 Mani Chandra , Francois Foucart , Charles F. Gammie

Sgr A* is probably the supermassive black hole being investigated most extensively due to its proximity. Several theoretical models for its steady state emission have been proposed in the past two decades. Both the radiative-inefficient…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Ya-Ping Li , Feng Yuan , Q. Daniel Wang

The effect of cooling on the outflow rate from an accretion disk around a black hole is investigated using a coupled Monte Carlo Total Variation Diminishing code. A correlation between the spectral states and the outflow rates is found as a…

High Energy Astrophysical Phenomena · Physics 2013-07-30 Sudip K. Garain , Himadri Ghosh. Sandip K. Chakrabarti

Anomalous radiative transfer (ART) theory is a generalization of classical radiative transfer theory. The present tutorial wants to show how Monte Carlo (MC) codes describing photons transport in anomalous media can be implemented. It is…

Computational Physics · Physics 2022-06-02 Tiziano Binzoni , Fabizio Martelli

We present a new continuum 3D radiative transfer code, MCFOST, based on a Monte-Carlo method. MCFOST can be used to calculate (i) monochromatic images in scattered light and/or thermal emission, (ii) polarisation maps, (iii) interferometric…

Astrophysics · Physics 2009-11-11 Christophe Pinte , Francois Menard , Gaspard Duchene , Pierre Bastien

Restricted path integral Monte Carlo simulations are used to calculate the equilibrium properties of hydrogen in the density and temperature range of $9.83 \times 10^{-4}\rm \leq \rho \leq 0.153 \rm gcm^{-3}$ and $5000 \leq T \leq 250 000…

Plasma Physics · Physics 2009-11-07 B. Militzer , D. M. Ceperley

Neutrino-matter interactions play an important role in the post-merger evolution of neutron star-neutron star and black hole-neutron star mergers. Most notably, they determine the properties of the bright optical/infrared transients…

High Energy Astrophysical Phenomena · Physics 2018-09-19 Francois Foucart , Matthew D. Duez , Lawerence E. Kidder , Ronny Nguyen , Harald P. Pfeiffer , Mark A. Scheel

Accreting black holes are believed to emit X-rays which then mediate information about strong gravity in the vicinity of the emission region. We report on a set of new routines for the Xspec package for analysing X-ray spectra of black-hole…

Astrophysics · Physics 2011-05-10 M. Dovciak , V. Karas , T. Yaqoob

Star-forming regions in galaxies are surrounded by vast reservoirs of gas capable of both emitting and absorbing Lyman-alpha (Lya) radiation. Observations of Lya emitters and spatially extended Lya haloes indeed provide insights into the…

Astrophysics of Galaxies · Physics 2020-08-26 Bing-Xin Lao , Aaron Smith

This paper presents a robust numerical method for calculating the total absorption rate of electromagnetic waves in magnetized plasmas, capable of determining the absorption ratio among different plasma components. The method adopts…

Plasma Physics · Physics 2025-11-18 Wanying Yu , Huasheng Xie , Aohua Mao , Haojie Ma , Zhengxiong Wang

We consider a temporal response of relativistically broadened line spectrum of iron from black hole accretion irradiated by an X-ray echo under strong gravity. The physical condition of accreting gas is numerically calculated in the context…

High Energy Astrophysical Phenomena · Physics 2020-04-08 Kaitlyn Porter , Keigo Fukumura

We propose a 2-temperature radial dynamical model of plasma flow near Sgr A* and fit the bremsstrahlung emission to extensive quiescent X-Ray Chandra data. The model extends from several arcseconds to black hole (BH) gravitational radius,…

High Energy Astrophysical Phenomena · Physics 2009-12-18 Roman V. Shcherbakov , Frederick K. Baganoff

By solving radiative transfer equations, we examine three-dimensional radiative properties of a magnetohydrodynamic accretion flow model confronting with the observed spectrum of Sgr A*, in the vicinity of supermassive black hole at the…

Astrophysics of Galaxies · Physics 2015-05-13 Y. Kato , M. Umemura , K. Ohsuga

We present general relativistic magnetohydrodynamic (GRMHD) numerical simulations of the accretion flow around the supermassive black hole in the Galactic centre, Sagittarius A* (Sgr A*). The simulations include for the first time radiative…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Salomé Dibi , Samia Drappeau , P. Chris Fragile , Sera Markoff , Jason Dexter

We calculate the atmospheric structure of an accretion disk around a Kerr black hole and obtain its X-ray spectrum, which exhibits prominent atomic transitions under certain circumstances. The gravitational and Doppler (red)shifts of the C…

We model the structure and evolution of black hole accretion disks, and their neighboring regions, using numerical simulations. The numerics is governed by the equations of general relativistic magneto-hydrodynamics (GRMHD). In particular,…

High Energy Astrophysical Phenomena · Physics 2018-06-25 Agnieszka Janiuk , Kostas Sapountzis , Jeremy Mortier , Ireneusz Janiuk

Wormholes are a hypothetical object that connects disparate points in spacetime. It is a theoretically well-motivated black hole alternative and offers a potential observationally testable arena for probing strong-field gravity with…

High Energy Astrophysical Phenomena · Physics 2026-05-08 Jing-ze Xia , Hong-xuan Jiang , Cheng Liu , Yosuke Mizuno

On-going measurements of the cosmic radiation (nuclear, electronic, and gamma-ray) are shedding new light on cosmic-ray physics. A comprehensive picture of these data relies on an accurate determination of the transport and source…

High Energy Astrophysical Phenomena · Physics 2010-07-08 A. Putze , L. Derome , D. Maurin

We briefly review a fruitful approach to compute a variety of radiation signatures of General Relativity (GR) originating from accretion disks in strong gravity. A set of transfer functions can be pre-computed and then employed to…

High Energy Astrophysical Phenomena · Physics 2019-07-23 Vladimir Karas , Michal Bursa , Michal Dovciak