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We use synthetic sightlines drawn through snapshots of the Technicolor Dawn simulations to explore how the statistics of neutral oxygen OI absorbers respond to hydrogen reionization. The ionization state of the circumgalactic medium (CGM)…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-26 Caitlin Doughty , Kristian Finlator

Moment methods are classical approaches that approximate the mesoscopic radiative transfer equation by a system of macroscopic moment equations. An expansion in the angular variables transforms the original equation into a system of…

Mathematical Physics · Physics 2023-08-17 Martin Frank , Benjamin Seibold

Several algorithms have been used for mass transfer between particles undergoing advective and macro-dispersive random walks. The mass transfer between particles is required for general reactions on, and among, particles. The mass transfer…

Computational Physics · Physics 2018-05-10 Michael J. Schmidt , Stephen D. Pankavich , David A. Benson

We describe a numerical algorithm to integrate the equations of radiation magnetohydrodynamics in multidimensions using Godunov methods. This algorithm solves the radiation moment equations in the mixed frame, without invoking any…

High Energy Astrophysical Phenomena · Physics 2012-03-05 Yan-Fei Jiang , James M. Stone , Shane W. Davis

We use a set of semi-numerical simulations based on Zel'dovich approximation, friends-of-friends algorithm and excursion set formalism to generate reionization maps of high dynamic range with a range of assumptions regarding the…

Astrophysics · Physics 2009-11-13 T. Roy Choudhury , M. G. Haehnelt , J. Regan

Coupled radiative-hydrodynamics simulations of the epoch of reionization aim to reproduce the propagation of ionization fronts during the transition before the overlap of HII regions. Many of these simulations use moment-based methods to…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-13 Nicolas Deparis , Dominique Aubert , Pierre Ocvirk , Jonathan Chardin , Joseph Lewis

Computer simulations of photon transport through an absorbing and/or scattering medium form an important research tool in astrophysics. Nearly all software codes performing such simulations for three-dimensional geometries employ the Monte…

Instrumentation and Methods for Astrophysics · Physics 2018-07-25 Peter Camps , Maarten Baes

We formulate a computationally efficient time-independent method based on the multi-electron molecular R-matrix formalism. This method is used to calculate transition matrix elements for the multi-photon ionization of atoms and molecules…

Atomic Physics · Physics 2022-05-10 Jakub Benda , Zdeněk Mašín

Early photoionization of the intergalactic medium is discussed in a nearly model-independent way, in order to investigate whether early structures corresponding to rare Gaussian peaks in a CDM model can photoionize the intergalactic medium…

Astrophysics · Physics 2009-10-07 Max Tegmark , Joseph Silk , Alain Blanchard

Full radiative transfer in 3D space has been solved to pursue the reionization history in an inhomogeneous universe. It has been shown that the reionization of an inhomogeneous universe is not a prompt event, but a fairly slow process.…

Astrophysics · Physics 2007-05-23 M. Umemura , T. Nakamoto , H. Susa

We present new calculations of the inhomogeneous process of cosmological reionization by carefully following the radiative transfer in pre-computed hydrodynamical simulations of galaxy formation. These new computations represent an…

Astrophysics · Physics 2009-11-07 Alexei O. Razoumov , Michael L. Norman , Tom Abel , Douglas Scott

Recent JWST observations have allowed for the first time to obtain comprehensive measurements of the ionizing photon production efficiency $\xi_\text{ion} $ for a wide range of reionization-epoch galaxies. We explore implications for the…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-04 Shikhar Asthana , Girish Kulkarni , Martin G. Haehnelt , James S. Bolton , Laura C. Keating , Charlotte Simmonds

High-redshift QSO spectra show large spatial fluctuations in the Ly-alpha opacity of the intergalactic medium on surprisingly large scales at z>~5.5. We present a radiative transfer simulation of cosmic reionization driven by galaxies that…

Cosmology and Nongalactic Astrophysics · Physics 2019-03-06 Girish Kulkarni , Laura C. Keating , Martin G. Haehnelt , Sarah E. I. Bosman , Ewald Puchwein , Jonathan Chardin , Dominique Aubert

The history of reionization reflects the cumulative injection of ionizing photons by sources and the absorption of ionizing photons by sinks. The latter process is traditionally described in terms of a "clumping factor" which encodes the…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-12 Frederick B. Davies , Sarah E. I. Bosman , Steven R. Furlanetto

Photomultiplier tubes (PMTs) are widely employed in particle and nuclear physics experiments. The accuracy of PMT waveform reconstruction directly impacts the detector's spatial and energy resolution. A key challenge arises when multiple…

High Energy Physics - Experiment · Physics 2026-02-06 Kainan Liu , Jingyu Huang , Guihong Huang , Jianyi Luo

The reionization epoch concludes when ionizing photons reach every corner of the Universe. Reionization has generally been assumed to be limited primarily by the rate at which galaxies produce ionizing photons, but the recent measurement of…

Cosmology and Nongalactic Astrophysics · Physics 2021-09-22 Frederick B. Davies , Sarah E. I. Bosman , Steven R. Furlanetto , George D. Becker , Anson D'Aloisio

Computationally expensive Radiative Transfer Models (RTMs) are widely used} to realistically reproduce the light interaction with the Earth surface and atmosphere. Because these models take long processing time, the common practice is to…

An additional channel opens for photoionization of atom $A$ by an electromagnetic field if it traverses a gas of atoms $B$ resonantly coupled to this field. We show that this channel, in which $A$ is ionized via resonant photoexcitation of…

Atomic Physics · Physics 2018-09-19 A. B. Voitkiv , C. Müller , S. F. Zhang , X. Ma

We present a new algorithm to solve the equations of radiation hydrodynamics (RHD) in a frequency-integrated, two-moment formulation. Novel features of the algorithm include i) the adoption of a non-local Variable Eddington Tensor (VET)…

Instrumentation and Methods for Astrophysics · Physics 2023-01-25 Shyam H. Menon , Christoph Federrath , Mark R. Krumholz , Rolf Kuiper , Benjamin D. Wibking , Manuel Jung

In this paper we study theoretically the process of electron capture between one-optical-electron atoms (e.g. hydrogenlike or alkali atoms) and ions at low-to-medium impact velocities ($v/v_e \approx 1$) working on a modification of an…

Atomic Physics · Physics 2009-11-07 F. Sattin