Nonequilibrium carbon ionization states and the extragalactic far-UV background with HeII absorption
Source: Astrophysics and Space Science, Volume 335, Number 1, September 2011 , pp. 211-215(5)
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.
Document Type: Research Article
Affiliations: 1: Institute of Physics, Southern Federal University, Stachki Ave. 194, Rostov-on-Don, 344090, Russia, Email: firstname.lastname@example.org 2: Raman Research Institute, Sadashiva Nagar, Bangalore, 560080, India
Publication date: 2011-09-01