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We present a ray-tracing technique for radiative transfer modeling of complex three-dimensional (3D) structures which include dense regions of high optical depth like in dense molecular clouds, circumstellar disks, envelopes of evolved…

Astrophysics · Physics 2009-11-11 J. Steinacker , A. Bacmann , Th. Henning

Polarised radio synchrotron emission from interstellar, intracluster and intergalactic magnetic fields is affected by frequency-dependent Faraday depolarisation. The maximum polarised intensity depends on the physical properties of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Tigran G. Arshakian , Rainer Beck

Massive stars provide feedback that shapes the interstellar medium of galaxies at all redshifts and their resulting stellar populations. Here we present three adaptive mesh refinement radiation hydrodynamics simulations that illustrate the…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-13 John H. Wise , Tom Abel , Matthew J. Turk , Michael L. Norman , Britton D. Smith

In this paper we present two efficient implementations of the diffusion approximation to be employed in Monte Carlo computations of radiative transfer in dusty media of massive circumstellar disks. The aim is to improve the accuracy of the…

Instrumentation and Methods for Astrophysics · Physics 2009-11-13 M. Min , C. P. Dullemond , C. Dominik , A. de Koter , J. W. Hovenier

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

Near-field radiative heat transfer (NFRHT) between irregularly shaped dielectric particles made of SiO2 and morphology characterized by Gaussian random spheres is studied. Particles are modeled using the discrete system Green's function…

Applied Physics · Physics 2023-01-16 Lindsay P. Walter , Eric J. Tervo , Mathieu Francoeur

We use hydrodynamic cosmological simulations in a 9.6 Mpc box to explore the evolution of the intergalactic medium (IGM) transmissivity from z=2 through the epoch of reionization. Reionization is achieved through an ultraviolet background…

Astrophysics · Physics 2009-11-10 Pascal Paschos , Michael L. Norman

Observations of galaxy luminosity function at high redshifts typically focus on fields of view of limited sizes preferentially containing bright sources. These regions possibly are overdense and hence biased with respect to the globally…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Girish Kulkarni , T. Roy Choudhury

Baryonic feedback fundamentally alters the total matter distribution on small to intermediate cosmological scales, posing a significant challenge for contemporary cosmological analyses. Direct tracers of the baryon distribution are…

Cosmology and Nongalactic Astrophysics · Physics 2025-07-24 Robert Reischke , Steffen Hagstotz

The first stars form in dark matter halos of masses ~10^6 M_sun as suggested by an increasing number of numerical simulations. Radiation feedback from these stars expels most of the gas from their shallow potential well of their surrounding…

Astrophysics · Physics 2009-11-13 John H. Wise , Tom Abel

We consider the problem of joint three-dimensional (3D) localization and material classification of unresolved space debris using a multispectral rotating point spread function (RPSF). The use of RPSF allows one to estimate the 3D locations…

Image and Video Processing · Electrical Eng. & Systems 2020-01-08 Chao Wang , Grey Ballard , Robert Plemmons , Sudhakar Prasad

In helioseismology, there is a well-known offset between observed and computed oscillation frequencies. This offset is known to arise from improper modeling of the near-surface layers of the Sun, and a similar effect must occur for models…

Astrophysics · Physics 2009-11-13 Hans Kjeldsen , Timothy R. Bedding , Joergen Christensen-Dalsgaard

Implicit and explicit raytracing-photoionisation algorithms have been implemented in the author's radiation-magnetohydrodynamics code. The algorithms are described briefly and their efficiency and parallel scaling are investigated. The…

Astrophysics of Galaxies · Physics 2012-01-31 Jonathan Mackey

One of the fundamental factors regulating the evolution of galaxies is stellar feedback. However, we still do not have strong observational constraints on the relative importance of the different feedback mechanisms (e.g. radiation, ionised…

A multi-domain spectral method for computing very high precision 3-D stellar models is presented. The boundary of each domain is chosen in order to coincide with a physical discontinuity (e.g. the star's surface). In addition, a…

Astrophysics · Physics 2009-06-11 S. Bonazzola , E. Gourgoulhon , J. -A. Marck

We examine the impact of helium reionization on the structure of the intergalactic medium (IGM). We model the reionization using a radiative transfer (RT) code coupled to the combined gravity hydrodynamics code Enzo. Neutral hydrogen and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 A. Meiksin , E. R. Tittley

Accurately measuring the masses of white dwarf stars is crucial in many astrophysical contexts (e.g., asteroseismology and cosmochronology). These masses are most commonly determined by fitting a model atmosphere to an observed spectrum;…

Solar and Stellar Astrophysics · Physics 2016-10-10 T. A. Gomez , M. H. Montgomery , T. Nagayama , D. P. Kilcrease , D. E. Winget

The emission from galactic black holes and Seyfert galaxies is generally understood in term of two-phase models (Haardt and Maraschi 1991, 1993). Such models postulate that a hot plasma coexists with relatively colder material in the inner…

Astrophysics · Physics 2009-11-10 Julien Malzac , Anne-Marie Dumont , Martine Mouchet

Resonance lines encode rich information about astrophysical sources and their environments, yet fully analytic treatments of multi-line radiative transfer remain almost entirely unexplored. We present exact, closed-form solutions for…

Astrophysics of Galaxies · Physics 2026-02-18 Ethan Stace , Aaron Smith , Kevin Lorinc , Olof Nebrin

We present a method for applying spatially resolved adiabatic and radiative loss processes to synthetic radio emission from hydrodynamic simulations of radio sources from active galactic nuclei (AGN). Lagrangian tracer particles, each…

High Energy Astrophysical Phenomena · Physics 2022-02-23 Patrick M. Yates-Jones , Ross J. Turner , Stanislav S. Shabala , Martin G. H. Krause