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Title:
Nonequilibrium carbon ionization states and the extragalactic far-UV background with HeII absorption
Authors:
Vasiliev, Evgenii O.; Sethi, Shiv K.; Nath, Biman B.
Affiliation:
AA(Institute of Physics, Southern Federal University), AB(Raman Research Institute), AC(Raman Research Institute)
Publication:
Astrophysics and Space Science, Vol. 335, No. 1, p. 211-215 (Ap&SS Homepage)
Publication Date:
09/2011
Origin:
SPRINGER
Keywords:
Cosmology: Theory, Diffuse radiation, Intergalactic medium, Quasars: General
Abstract Copyright:
(c) 2011: Springer Science+Business Media B.V.
DOI:
10.1007/s10509-010-0585-6
Bibliographic Code:
2011Ap&SS.335..211V

Abstract

Using nonequilibrium calculations of the ionic states and the recently calculated extragalactic ultraviolet background radiation with absorption by intergalactic HeII we determine the ratios of CIII to CIV expected at z˜2-3, as functions of metallicity, gas density and temperature. We constrain the spectrum of the extragalactic ultraviolet background radiation by fitting the observed abundance ratios carbon ions at these redshifts with those expected from different models of the background radiation. Our analysis of the observed ratios shows that `delayed reionization' models, which assume a large fraction of HeII at z˜3, is not favored by data. Our results suggest that HeII reionization was inhomogeneous, consistent with the predictions from recent simulations.
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Database: Astronomy
Physics
arXiv e-prints