Astrophysics and Space Science

, Volume 335, Issue 1, pp 211–215

Nonequilibrium carbon ionization states and the extragalactic far-UV background with HeII absorption

  • Evgenii O. Vasiliev
  • Shiv K. Sethi
  • Biman B. Nath
Original Article

DOI: 10.1007/s10509-010-0585-6

Cite this article as:
Vasiliev, E.O., Sethi, S.K. & Nath, B.B. Astrophys Space Sci (2011) 335: 211. doi:10.1007/s10509-010-0585-6
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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.

Keywords

Cosmology: Theory Diffuse radiation Intergalactic medium Quasars: General 

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Evgenii O. Vasiliev
    • 1
  • Shiv K. Sethi
    • 2
  • Biman B. Nath
    • 2
  1. 1.Institute of PhysicsSouthern Federal UniversityRostov-on-DonRussia
  2. 2.Raman Research InstituteBangaloreIndia