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The radiative transfer equation (RTE) models the transport of light inside photonic scattering samples such as paint, foam and tissue. Analytic approximations to solve the RTE fail for samples with strong absorption and dominant anisotropic…

Optics · Physics 2022-03-24 Ozan Akdemir , Ad Lagendijk , Willem L. Vos

The radiation transport problem in the plane-parallel medium with the large velocity gradient is considered. The Sobolev approximation is used. The effects of continuum absorption and line overlap are taken into account. The photon loss…

Astrophysics of Galaxies · Physics 2021-02-03 Aleksandr Nesterenok

The "Reduced Speed of Light" (RSL) approximation is commonly used to speed up radiative transfer calculations in cosmological simulations. However, it has been shown previously that the RSL approximation leads to photon non-conservation in…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-03 Nickolay Y. Gnedin

Radiative feedback (RFB) from stars plays a key role in galaxies, but remains poorly-understood. We explore this using high-resolution, multi-frequency radiation-hydrodynamics (RHD) simulations from the Feedback In Realistic Environments…

We discuss the efficiency of Monte Carlo methods in solving continuum radiative transfer problems. The sampling of the radiation field and convergence of dust temperature calculations in the case of optically thick clouds are both studied.…

Astrophysics · Physics 2009-11-10 M. Juvela

We explore the application of Monte Carlo transport methods to solving coupled radiation-hydrodynamics problems. We use a time-dependent, frequency-dependent, 3-dimensional radiation transport code, that is special relativistic and includes…

Instrumentation and Methods for Astrophysics · Physics 2015-06-19 Nathaniel Roth , Daniel Kasen

We describe a general radiative equilibrium and temperature correction procedure for use in Monte Carlo radiation transfer codes with sources of temperature-independent opacity, such as astrophysical dust. The technique utilizes the fact…

Astrophysics · Physics 2010-04-08 J. E. Bjorkman , Kenneth Wood

Momentum deposition by radiation pressure from young, massive stars may help to destroy molecular clouds and unbind stellar clusters by driving large-scale outflows. We extend our previous numerical radiation hydrodynamic study of…

Astrophysics of Galaxies · Physics 2017-12-06 Sudhir Raskutti , Eve C. Ostriker , M. Aaron Skinner

Gas metallicity $Z$ and the related dust-to-gas ratio $f_\textrm{d}$ can influence the growth of HII regions via metal line cooling and UV absorption. We model these effects in star-forming regions containing massive stars. We compute…

Astrophysics of Galaxies · Physics 2021-01-06 Ahmad A. Ali

This paper proposes a unified gas-kinetic particle (UGKP) method for the frequency-dependent photon transport process. The photon transport is a typical multiscale process governed by the nonlinear radiative transfer equations (RTE). The…

Numerical Analysis · Mathematics 2023-01-18 Weiming Li , Chang Liu , Peng Song

We developed a three-dimensional radiative transfer code for an ultra-relativistic background flow-field by using the Monte Carlo (MC) method in the context of gamma-ray burst (GRB) emission. For obtaining reliable simulation results in the…

High Energy Astrophysical Phenomena · Physics 2017-09-13 Ayako Ishii , Naofumi Ohnishi , Hiroki Nagakura , Hirotaka Ito , Shoichi Yamada

By taking into account photon absorption, we investigate the vertical structure of accretion flows with comparable radiation and gas pressures. We consider two separate energy equations for matter and radiation in the diffusion limit. In…

High Energy Astrophysical Phenomena · Physics 2019-08-10 Maryam Samadi , Shahram Abbassi , Wei-Min Gu

We compare numerical methods for solving the radiative transfer equation in the context of the photoionization of intergalactic gaseous hydrogen and helium by a central radiating source. Direct integration of the radiative transfer equation…

Instrumentation and Methods for Astrophysics · Physics 2023-01-18 Ka-Hou Leong , Avery Meiksin , Althea Lai , K. H. To

The rapid-neutron capture process ($r$ process) is identified as the producer of about 50\% of elements heavier than iron. This process requires an astrophysical environment with an extremely high neutron flux over a short amount of time…

Nuclear Experiment · Physics 2019-06-26 A. C. Larsen , A. Spyrou , S. N. Liddick , M. Guttormsen

Biasing or importance sampling is a powerful technique in Monte Carlo radiative transfer, and can be applied in different forms to increase the accuracy and efficiency of simulations. One of the drawbacks of the use of biasing is the…

Instrumentation and Methods for Astrophysics · Physics 2016-05-11 Maarten Baes , Karl D. Gordon , Tuomas Lunttila , Simone Bianchi , Peter Camps , Mika Juvela , Rolf Kuiper

We trap absorbing micro-particles in air by photophoretic forces generated using a single loosely focused Gaussian trapping beam. We measure a component of the radial Brownian motion of a trapped particle cluster and determine the power…

Soft Condensed Matter · Physics 2016-11-03 Sudipta K. Bera , Avinash Kumar , Souvik Sil , Tushar Kanti Saha , Tanumoy Saha , Ayan Banerjee

This work is concerned with the numerical simulation of plasma arc interaction with aerospace substrates under conditions akin to lightning strike and in particular with the accurate calculation of radiative heat losses. These are important…

Computational Physics · Physics 2022-01-26 M. Apsley , S. T. Millmore , N. Nikiforakis

We present a model for the interaction between dust and radiation fields in the radiation hydrodynamic code AREPO-RT, which solves the moment-based radiative transfer equations on an unstructured moving mesh. Dust is directly treated using…

Astrophysics of Galaxies · Physics 2019-12-09 Ryan McKinnon , Rahul Kannan , Mark Vogelsberger , Stephanie O'Neil , Paul Torrey , Hui Li

Cooperative spontaneous emission of a single photon from a cloud of N atoms modifies substantially the radiation pressure exerted by a far-detuned laser beam exciting the atoms. On one hand, the force induced by photon absorption depends on…

The ability to directly measure the momentum distribution of quantum gases is both unique to these systems and pivotal in extracting many other important observables. Here we use Raman transitions to measure the momentum distribution of a…

Quantum Gases · Physics 2020-01-15 Constantine Shkedrov , Gal Ness , Yanay Florshaim , Yoav Sagi