THE METAGALACTIC IONIZING BACKGROUND: A CRISIS IN UV PHOTON PRODUCTION OR INCORRECT GALAXY ESCAPE FRACTIONS?

@article{Shull2015THEMI,
  title={THE METAGALACTIC IONIZING BACKGROUND: A CRISIS IN UV PHOTON PRODUCTION OR INCORRECT GALAXY ESCAPE FRACTIONS?},
  author={J. Michael Shull and Joshua Moloney and Charles W. Danforth and Evan M. Tilton},
  journal={The Astrophysical Journal},
  year={2015},
  volume={811}
}
Recent suggestions of a “photon underproduction crisis” have generated concern over the intensity and spectrum of ionizing photons in the metagalactic ultraviolet background (UVB). The balance of hydrogen photoionization and recombination determines the opacity of the low-redshift intergalactic medium (IGM). We calibrate the hydrogen photoionization rate ( Γ H ?> ) by comparing Hubble Space Telescope spectroscopic surveys of the low-redshift column density distribution of H i absorbers and the… 

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References

SHOWING 1-10 OF 56 REFERENCES

The Metagalactic Ionizing Radiation Field at Low Redshift

We compute the ionizing radiation field at low redshift, arising from Seyferts, QSOs, and starburst galaxies. This calculation combines recent Seyfert luminosity functions, extrapolated ultraviolet

RADIATIVE TRANSFER IN A CLUMPY UNIVERSE. IV. NEW SYNTHESIS MODELS OF THE COSMIC UV/X-RAY BACKGROUND

We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. Five new main components are added to our radiative

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

A NEW CALCULATION OF THE IONIZING BACKGROUND SPECTRUM AND THE EFFECTS OF He ii REIONIZATION

The ionizing background determines the ionization balance and the thermodynamics of the cosmic gas. It is therefore a fundamental ingredient to theoretical and empirical studies of both the

Extreme feedback and the epoch of reionization: clues in the local universe

The source responsible for reionizing the universe at z>6 remains uncertain. While an energetically adequate population of star-forming galaxies may be in place, it is unknown whether a large enough

AN HST/COS SURVEY OF THE LOW-REDSHIFT INTERGALACTIC MEDIUM. I. SURVEY, METHODOLOGY, AND OVERALL RESULTS

We use high-quality, medium-resolution Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) observations of 82 UV-bright active galactic nuclei (AGNs) at redshifts zAGN < 0.85 to construct

The intergalactic medium over the last 10 billion years – I. Lyα absorption and physical conditions

The intergalactic medium (IGM) is the dominant reservoir of baryons at all cosmic epochs. In this paper, we investigate the evolution of the IGM from z = 2 → 0i n (48h −1 Mpc) 3 , 110million particle

THE COS-HALOS SURVEY: PHYSICAL CONDITIONS AND BARYONIC MASS IN THE LOW-REDSHIFT CIRCUMGALACTIC MEDIUM

We analyze the physical conditions of the cool, photoionized (T ∼104 K) circumgalactic medium (CGM) using the COS-Halos suite of gas column density measurements for 44 gaseous halos within 160 kpc of

HST-COS OBSERVATIONS OF AGNs. II. EXTENDED SURVEY OF ULTRAVIOLET COMPOSITE SPECTRA FROM 159 ACTIVE GALACTIC NUCLEI

The ionizing fluxes from quasars and other active galactic nuclei (AGNs) are critical for interpreting their emission-line spectra and for photoionizing and heating the intergalactic medium. Using

The Direct Detection of Lyman Continuum Emission from Star-forming Galaxies at z~3

We present the results of rest-frame UV spectroscopic observations of a sample of 14 z ~ 3 star-forming galaxies in the SSA 22a field. These spectra are characterized by unprecedented depth in the
...