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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 develop a new numerical scheme for solving the radiative transfer equation in a spherically symmetric system. This scheme does not rely on any kind of diffusion approximation and it is accurate for optically thin, thick, and intermediate…

Instrumentation and Methods for Astrophysics · Physics 2018-05-31 Torsten Stamer , Shu-ichiro Inutsuka

When modelling the ionisation of gas in the intergalactic medium after reionisation, it is standard practice to assume a uniform radiation background. This assumption is not always appropriate; models with radiative transfer show that…

Cosmology and Nongalactic Astrophysics · Physics 2020-09-02 Teresita Suarez , Andrew Pontzen

We study a one-dimensional model of radiative heat transfer for which the effect of the electromag- netic field is only from the scalar potential and thereby ignoring the vector potential contribution. This is a valid assumption when the…

Mesoscale and Nanoscale Physics · Physics 2017-03-22 Jiebin Peng , Han Hoe Yap , Gang Zhang , Jian-Sheng Wang

A substantial fraction of all ionizing photons originate from radiative recombinations. However, in radiative transfer calculations this recombination radiation is often assumed to be absorbed 'on-the-spot' because for most methods the…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-01 Milan Raičević , Andreas H. Pawlik , Joop Schaye , Alireza Rahmati

We introduce new methods for the numerical solution of general Hamiltonian boundary value problems. The main feature of the new formulae is to produce numerical solutions along which the energy is precisely conserved, as is the case with…

Numerical Analysis · Mathematics 2014-11-26 P. Amodio , L. Brugnano , F. Iavernaro

Cosmic rays are an important source of heating in the interstellar medium, in particular in dense molecular cloud cores shielded from the external ultraviolet radiation field. The limits placed on the cosmic-ray ionization rate from…

Solar and Stellar Astrophysics · Physics 2015-02-12 Daniele Galli , Marco Padovani

To facilitate the study of black hole fueling, star formation, and feedback in galaxies, we outline a method for treating the radial forces on interstellar gas due to absorption of photons by dust grains. The method gives the correct…

Astrophysics of Galaxies · Physics 2015-06-04 G. S. Novak , J. P. Ostriker , L. Ciotti

We propose use of the thickness of the ionisation front as a discriminant between alternative modes of reionisation in the early universe, by stars or by miniquasars. Assuming a photoionisation-recombination balance, we find that for…

Astrophysics · Physics 2007-05-23 Saleem Zaroubi , Joseph Silk

A nonsingular analytical solution for the transfer equation in a pure absorber is obtained in central symmetry and in a monochromatic radiation field. The native regular singularity of the equation is removed by applying a linear…

Astrophysics · Physics 2007-05-23 C. H. Aboughantous

Reversible and coherent storage of light in atomic medium is a key-stone of future quantum information applications. In this work, arbitrary two-dimensional images are slowed and stored in warm atomic vapor for up to 30 $\mu$s, utilizing…

Quantum Physics · Physics 2008-06-17 M. Shuker , O. Firstenberg , R. Pugatch , A. Ron , N. Davidson

A new two-dimensional axi-symmetric ultraviolet radiative transfer code is presented, which is used to calculate photodissociation and ionization rates for use in chemistry models of flaring circumstellar disks. Scattering and absorption of…

A new set of discrete ordinates is proposed for one-dimensional radiative transfer in spheres with central symmetry. The set is structured with un-normalized circular functions. This resulted in a conservative and closed set of discrete…

Astrophysics · Physics 2007-05-23 Charles H. Aboughantous

Here we formulate and solve the 3D radiative transfer problem of the polarization of the solar continuous radiation. Our approach takes into account not only the anisotropy of the continuum radiation, but also the symmetry-breaking effects…

Astrophysics · Physics 2011-02-11 J. Trujillo Bueno , N. Shchukina

A major goal in solar physics has during the last five decades been to find how energy flux generated in the solar convection zone is transported and dissipated in the outer solar layers. Progress in this field has been slow and…

Astrophysics · Physics 2007-05-23 Viggo H. Hansteen , Mats Carlsson , Boris Gudiksen

Accurate accounting of particle number and 4-momentum in radiative transfer may be facilitated by the use of transport equations that allow transparent conversion between volume and surface integrals in both spacetime and momentum space.…

Astrophysics · Physics 2016-11-09 Christian Y. Cardall

Astrophysical plasmas are subject to a tight connection between magnetic fields and the diffusion of particles, which leads to an anisotropic transport of energy. Under the fluid assumption, this effect can be reduced to an…

Astrophysics of Galaxies · Physics 2016-01-13 Yohan Dubois , Benoît Commerçon

Geometric details of a nuclear reaction zone, at the time of particle emission, can be restored from low relative-velocity particle-correlations, following imaging. Some of the source details get erased and are a potential cause of problems…

Nuclear Theory · Physics 2009-11-10 P. Danielewicz , D. A. Brown , M. Heffner , S. Pratt , R. Soltz

A radiative transfer scheme is presented, based on a moment description of the equation of radiative transfer and the so-called ``M1 closure model'' for the Eddington tensor. This model features a strictly hyperbolic transport step for…

Astrophysics · Physics 2009-11-13 Dominique Aubert , Romain Teyssier

We investigate the 21 cm signals from the UV ionizing sources in the reionization epoch. The formation and evolution of 21 cm emission and absorption regions depend essentially on the kinetics of photons in the physical and frequency…

Astrophysics · Physics 2011-02-11 Jiren Liu , Jing-Mei Qiu , Long-Long Feng , Chi-Wang Shu , Li-Zhi Fang