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2011MNRAS.410.2193M - Mon. Not. R. Astron. Soc., 410, 2193-2202 (2011/February-1)
Revisiting the He II to H I ratio in the intergalactic medium.
MUZAHID S., SRIANAND R. and PETITJEAN P.
Abstract (from CDS):
We show that, if we constrain the fit of the H I and/or He II absorption profiles with the presence of metal components, we can accommodate η values in the range 15-100 in these systems, assuming that broadening is intermediate between pure thermal and pure turbulent.
While simple photoionization models reproduce the observed N(O VI)/N(C IV) ratio, they fail to produce low η values, in contrast to models with high temperatures (i.e T ≥ 105 K). The Doppler parameters measured for different species suggest a multiphase nature of the absorbing regions. Therefore, if low η values were to be confirmed, we would favour a multiphase model in which most of the gas is at a high temperature (>105 K) but the metals, and in particular C IV, are due to a lower-temperature ( ∼ few 104 K) photoionized gas.
Abstract Copyright: 2010 The Authors. Journal compilation2010 RAS
Journal keyword(s): intergalactic medium - quasars: absorption lines - quasars: individual: HE 2347-4342
Simbad objects: 2
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