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|Title:||Carbon ionization states and the cosmic far-UV background with He II absorption|
|Authors:||Vasiliev, Evgenii O.|
Nath, Biman B.
|Publisher:||IOP Publishing Ltd.|
|Citation:||Astrophysical Journal, 2010, Vol. 719, p1343|
|Abstract:||We constrain the spectrum of the cosmic ultraviolet background radiation by fitting the observed abundance ratios of carbon ions at z ~ 2-3 with those expected from different models of the background radiation. We use the recently calculated modulation of the background radiation between 3 and 4 Ryd due to resonant line absorption by intergalactic He II and determine the ratios of C III to C IV expected at these redshifts, as functions of metallicity, gas density, and temperature. Our analysis of the observed ratios shows that "delayed reionization" models, which assume a large fraction of He II at z ~ 3, are not favored by data. Our results suggest that He II reionization was inhomogeneous, consistent with the predictions from recent simulations.|
|Description:||Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)|
|Copyright:||2010 IOP Publishing for the American Astronomical Society|
|Appears in Collections:||Research Papers (A&A)|
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