Radiative Transfer in a Clumpy Universe. III. The Nature of Cosmological Ionizing Sources

  title={Radiative Transfer in a Clumpy Universe. III. The Nature of Cosmological Ionizing Sources},
  author={Piero Madau and Francesco Haardt and Martin J. Rees},
  journal={The Astrophysical Journal},
  pages={648 - 659}
The history of the transition from a neutral intergalactic medium (IGM) to one that is almost fully ionized can reveal the character of cosmological ionizing sources. We study the evolution of the volume filling factors of H II and He III regions in a clumpy IGM and discuss the implications for rival reionization scenarios of the rapid decline observed at z≳3 in the space density of optical and radio-loud quasars and of the large population of star-forming galaxies recently discovered at the… 
The redshift evolution of escape fraction of hydrogen ionizing photons from galaxies
Using our cosmological radiative transfer code, we study the implications of the updated QSO emissivity and star formation history for the escape fraction (f_esc) of hydrogen ionizing photons from
Non-uniform reionization by galaxies and its effect on the cosmic microwave background
We present predictions for the reionization of the intergalactic medium (IGM) by stars in high-redshift galaxies, based on a semi-analytic model of galaxy formation. We calculate ionizing
Effect of primordial non-Gaussianities on the far-UV luminosity function of high-redshift galaxies: implications for cosmic reionization
Understanding how the intergalactic medium (IGM) was reionized at z & 6 is one of the big challenges of current high redshift astronomy. It re quires modelling the collapse of the first astrophysical
An Ionizing Ultraviolet Background Dominated by Massive Stars
We discuss the implications of a stellar-dominated UV background at high redshifts for the star formation history of Lyman break galaxies (LBGs) and the thermal and ionization state of the
I present a simple calculation of the expected mean CO brightness temperature from the large-scale distribution of galaxies during cosmic reionization. The calculation is based on the cosmic star
The physics of the intergalactic medium
Intergalactic space is filled with a pervasive medium of ionized gas, the Intergalactic Medium (IGM). A residual neutral fraction is detected in the spectra of Quasi-Stellar Objects at both low and
Reionization of the Inhomogeneous Universe
A model of the density distribution in the intergalactic medium (IGM), motivated by that found in numerical simulations, is used to demonstrate the effect of a clumpy IGM and discrete sources on the
Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity
We investigate the implications of the intergalactic opacity for the evolution of the cosmic UV luminosity density and its sources. Our main constraint is our measurement of the Lyα forest opacity at
The effect of stellar feedback and quasar winds on the active galactic nucleus population
In order to constrain the physical processes that regulate and downsize the active galactic nucleus (AGN) population, the predictions of the model for the rise of galaxies and active nuclei (MORGANA)
Reionization of Hydrogen and Helium by Early Stars and Quasars
We compute the reionization histories of hydrogen and helium caused by the ionizing radiation fields produced by stars and quasars. For the quasars we use a model based on halo-merger rates that


Signatures of Stellar Reionization of the Universe
The high ionization level and nonzero metallicity (~1% Z☉) of the intergalactic gas at redshifts z ≲ 5 implies that nonlinear structure had started to form in the universe at earlier times than we
Measurement of the opacity of ionized helium in the intergalactic medium
DETERMINATION of the density and ionization state of diffuse primordial gas in the intergalactic medium (IGM) is an important step towards understanding the nature of dark matter and the formation of
Radiative Transfer in a Clumpy Universe. II. The Ultraviolet Extragalactic Background
We present a detailed calculation of the propagation of AGN-like ionizing radiation through the intergalactic space. We model the ionization state of absorbing clouds, and show that the universe will
Radiative transfer in a clumpy universe: The colors of high-redshift galaxies
We assess the effects of the stochastic attenuation produced by intervening QSO absorption systems on the broadband colors of galaxies at cosmological distances. We compute the H I opacity of a
The generalization of the classical H II region problem to the case of a point source of ionizing radiation in a cosmologically expanding gas in a Friedmann-Robertson-Walker universe is summarized.
Synthetic properties of starburst galaxies
We present the results of an extensive grid of evolutionary synthesis models for populations of massive stars. The parameter space has been chosen to correspond to conditions typically found in
High-redshift galaxies, their active nuclei and central black holes
We demonstrate that the luminosity function of the recently detected population of actively star-forming galaxies at redshift z = 3 and the B-band luminosity function of quasi-stellar objects (QSOs)
21 Centimeter Tomography of the Intergalactic Medium at High Redshift
We investigate the 21 cm signature that may arise from the intergalactic medium (IGM) prior to the epoch of full reionization (z > 5). In scenarios in which the IGM is reionized by discrete sources
The Redshift Evolution of the Metagalactic Ionizing Flux Inferred from Metal Line Ratios in the Lyman Forest
Metal line ratios in a sample of 13 quasar spectra obtained with the HIRES spectrograph on the Keck I Telescope have been analyzed to characterize the evolution of the metagalactic ionizing flux near
The Star Formation History of Field Galaxies
We develop a method for interpreting faint galaxy data which focuses on the integrated light radiated from the galaxy population as a whole. The emission history of the universe at ultraviolet,