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Many relativistic plasma environments in high-energy astrophysics, including pulsar wind nebulae, hot accretion flows onto black holes, relativistic jets in active galactic nuclei and gamma-ray bursts, and giant radio lobes, are naturally…

High Energy Astrophysical Phenomena · Physics 2019-07-23 Dmitri A. Uzdensky

Hamiltonian Monte Carlo is a prominent Markov Chain Monte Carlo algorithm, which employs symplectic integrators to sample from high dimensional target distributions in many applications, such as statistical mechanics, Bayesian statistics…

Numerical Analysis · Mathematics 2025-02-13 Geoffrey McGregor , Andy T. S. Wan

An improved formulation for the X-factor is proposed. The statement that the velocity-integrated radiation temperature of the $\COone$ line, $I(\CO)$, ``counts'' optically thick clumps is quantified using the formalism of \citet{Martin84}…

Astrophysics · Physics 2008-11-26 W. F. Wall

Density matrix quantum Monte Carlo (DMQMC) is used to sample exact-on-average $N$-body density matrices for uniform electron gas systems of up to 10$^{124}$ matrix elements via a stochastic solution of the Bloch equation. The results of…

Strongly Correlated Electrons · Physics 2016-09-14 Fionn D. Malone , N. S. Blunt , Ethan W. Brown , D. K. K. Lee , J. S. Spencer , W. M. C. Foulkes , James J. Shepherd

We introduce the Quantization Monte Carlo method to solve thermal radiative transport equations with possibly several collision regimes, ranging from few collisions to massive number of collisions per time unit. For each particle in a given…

Computational Physics · Physics 2024-09-13 Laetitia Laguzet , Gabriel Turinici

Compton scattering of a laser beam with a relativistic electron beam has been used to generate intense, highly polarized and nearly monoenergetic x-ray or gamma-ray beams at many facilities. The ability to predict the spatial, spectral and…

Accelerator Physics · Physics 2011-05-09 Changchun Sun , Ying K. Wu

An approximate treatment of exchange in finite-temperature path integral Monte Carlo simulations for fermions has been proposed. In this method, some of the fine details of density matrix due to permutations have been smoothed over or…

Statistical Mechanics · Physics 2015-05-13 D. Y. Sun

We develop a method of analyzing radio frequency spectral line observations to derive data on the temperature, density, velocity, and molecular abundance of the emitting gas. The method incorporates a radiative transfer code with a new…

Astrophysics · Physics 2009-11-10 Eric Keto , George B. Rybicki , Edwin A. Bergin , Rene Plume

A novel covariant formalism for the treatment of the transfer and Compton scattering of partially polarized light is presented. This was initially developed to aid in the computation of relativistic corrections to the polarization generated…

Astrophysics · Physics 2016-08-30 Jamie Portsmouth , Edmund Bertschinger

In this work we present a theoretical study on the propagation of light in heterogeneous systems with fluctuating optical properties. To understand the consequences of the fluctuations we perform numerical calculations with uniform and non…

Optics · Physics 2015-07-07 Emiliano Terán-Bobadilla , Eugenio Méndez

We present an efficient heating/cooling method coupled with chemistry and ultraviolet (UV) radiative transfer, which can be applied to numerical simulations of the interstellar medium (ISM). We follow the time-dependent evolution of…

Astrophysics of Galaxies · Physics 2022-12-28 Jeong-Gyu Kim , Munan Gong , Chang-Goo Kim , Eve C. Ostriker

We formulate eikonal approximation to the calculation of high energy scattering amplitude in the frame where both colliding objects are very energetic. We express the eikonal scattering matrix in terms of the color charge densities of the…

High Energy Physics - Phenomenology · Physics 2009-02-12 T. Altinoluk , A. Kovner , J. Peressutti

A new, fully dynamic and self-consistent radiation hydrodynamics code, suitable for the calculation of supernovae light curves and continuum spectra, is described. It is a multigroup (frequency-dependent) code and includes all important…

Astrophysics · Physics 2009-10-22 Xiao-he Zhang , Peter Sutherland

Compton scattering of photons by nonrelativistic particles is thought to play an important role in forming the radiation spectrum of many astrophysical systems. Here we derive the time-dependent photon kinetic equation that describes…

Astrophysics · Physics 2009-10-30 Dimitrios Psaltis , Frederick K. Lamb

We present the hybrid opacity code SCO-RCG which combines statistical approaches with fine-structure calculations. Radial integrals needed for the computation of detailed transition arrays are calculated by the code SCO (Super-configuration…

Atomic Physics · Physics 2019-04-30 Jean-Christophe Pain , Franck Gilleron , Quentin Porcherot , Thomas Blenski

Ionising feedback from massive stars dramatically affects the interstellar medium local to star forming regions. Numerical simulations are now starting to include enough complexity to produce morphologies and gas properties that are not too…

Instrumentation and Methods for Astrophysics · Physics 2015-12-23 D. A. Hubber , B. Ercolano , J. Dale

We present a unified view of the frequency dependence of the various scattering processes involved when a neutral hydrogen atom interacts with a monochromatic, linearly-polarized photon. A computational approach is employed of the atom…

Atomic Physics · Physics 2016-06-06 Swaantje J. Grunefeld , Michael W. J. Bromley , Yongjun Cheng

In this paper, we propose a new interactive compression scheme for omnidirectional images. This requires two characteristics: efficient compression of data, to lower the storage cost, and random access ability to extract part of the…

Multimedia · Computer Science 2020-08-24 Navid Mahmoudian Bidgoli , Thomas Maugey , Aline Roumy

We present an approach to calculation of point defect optical and thermal ionization energies based on the highly accurate quantum Monte Carlo methods. The use of an inherently many-body theory that directly treats electron correlation…

Materials Science · Physics 2015-06-11 Elif Ertekin , Lucas K. Wagner , Jeffrey C. Grossman

Compton scattering between electrons and photons plays a crucial role in astrophysical plasmas. Many important aspects of this process can be captured by using the so-called Compton scattering kernel. For isotropic media, exact analytic…

Cosmology and Nongalactic Astrophysics · Physics 2019-10-03 Abir Sarkar , Jens Chluba , Elizabeth Lee