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We model gas cooling in high-resolution N-body simulations in order to investigate the formation of the first generation of stars. We follow a region of a LCDM universe especially selected to contain a rich cluster by the present day. The…

The first sources of ionizing radiation to condense out of the dark and neutral IGM sent ionization fronts sweeping outward through their surroundings, overtaking other condensed objects and photoevaporating them. This feedback of universal…

Astrophysics · Physics 2007-05-23 Paul R. Shapiro , Alejandro C. Raga

Observations of the Epoch of Reionization (EoR) have the potential to answer long-standing questions of astrophysical interest regarding the nature of the first luminous sources and their effects on the intergalactic medium (IGM). We…

Large-scale reionization simulations are described which combine the results of cosmological N-body simulations that model the evolving density and velocity fields and identify the galactic halo sources, with ray-tracing radiative transfer…

We investigate self-shielding of intergalactic hydrogen against ionizing radiation in radiative transfer simulations of cosmic reionization carefully calibrated with Lyman alpha forest data. While self-shielded regions manifest as…

Cosmology and Nongalactic Astrophysics · Physics 2018-06-13 Jonathan Chardin , Girish Kulkarni , Martin G. Haehnelt

The temporal evolution of the ionizing UV background radiation field at high redshift provides a probe of the evolution of the early star formation rate. By comparing the observed levels of absorption in the highest redshift quasar spectra…

Astrophysics · Physics 2009-11-07 Renyue Cen , Patrick McDonald

The supermassive black holes (SMBHs) that power active galactic nuclei found at $z > 6$ were formed during the epoch of reionization. Because reionization is an inhomogeneous process, the physical properties of SMBH host galaxy environments…

Astrophysics of Galaxies · Physics 2024-08-21 Phoebe R. Upton Sanderbeck , Jarrett L. Johnson , Madeline A. Marshall

Semi-numeric methods have made it possible to efficiently model the epoch of reionisation (EoR). While most implementations involve a reduction to a simple three-parameter model, we introduce a new mass-dependent ionising efficiency…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-12 Daegene Koh , John H. Wise

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

Small galaxies are thought to be the main contributors to the ionising budget of the Universe before reionisation was complete. There have been a number of numerical studies trying to quantify their ionising efficiency through the escape…

Astrophysics of Galaxies · Physics 2015-10-26 M. Trebitsch , J. Blaizot , J. Rosdahl

Galactic stellar halos have long been considered to contain fossil information on early dynamical and chemical evolution of galaxies. We propose that the surface brightness distributions of old stellar halos contain the influence of…

Astrophysics · Physics 2009-11-11 Kenji Bekki , Masashi Chiba

Theoretical studies and current observations of the high-redshift intergalactic medium (IGM) indicate that at least two cosmic transitions occur by the time the universe reaches gas metallicities of about $10^{-3}$ of solar values. These…

Astrophysics · Physics 2009-11-11 Aparna Venkatesan

Early in the reionization process, the intergalactic medium (IGM) would have been quite inhomogeneous on small scales, due to the low Jeans mass in the neutral IGM and the hierarchical growth of structure in a cold dark matter Universe.…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-21 J. D. Emberson , Rajat M. Thomas , Marcelo A. Alvarez

A model of the density distribution in the intergalactic medium, motivated by that found in numerical simulations, is used to demonstrate the effect of a clumpy IGM and discrete sources on the reionization of the universe. In an…

Astrophysics · Physics 2009-10-31 Jordi Miralda-Escude , Martin Haehnelt , Martin J. Rees

We examine the reionization history of present-day galaxies by explicitly tracing the building blocks of halos from the Cosmic Reionization On Computers project. We track dark matter particles that belong to $z=0$ halos to trace the neutral…

Cosmology and Nongalactic Astrophysics · Physics 2019-12-02 Hanjue Zhu , Camille Avestruz , Nickolay Y. Gnedin

We explore the impacts of ultraviolet (UV) radiation feedback on galaxies during the epoch of reionisation by cosmological simulations in which hydrodynamics and the transfer of the H and He ionising photons are consistently coupled.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Kenji Hasegawa , Benoit Semelin

It has been argued that low-luminosity dwarf galaxies are the dominant source of ionizing radiation during cosmological reionization. The fraction of ionizing radiation that escapes into the intergalactic medium from dwarf galaxies with…

Astrophysics · Physics 2011-02-11 John H. Wise , Renyue Cen

Known populations of QSOs appear to fall short of producing the ionizing flux required for re-ionizing the universe. The alternative, galaxies as sources of ionizing photons, suffers from the problem that known types of galaxies are almost…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Michael Rauch

Cosmic reionization was driven by the imbalance between early sources and sinks of ionizing radiation, both of which were dominated by small-scale structure and are thus usually treated in cosmological reionization simulations by subgrid…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-05 Yi Mao , Jun Koda , Paul R. Shapiro , Ilian T. Iliev , Garrelt Mellema , Hyunbae Park , Kyungjin Ahn , Michele Bianco

The first sources of ionizing radiation to condense out of the dark and neutral IGM sent ionization fronts sweeping outward through their surroundings, overtaking other condensed objects and photoevaporating them. This feedback of universal…

Astrophysics · Physics 2007-05-23 Paul R. Shapiro , Alejandro C. Raga
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