Are Lyman clouds non-spherical?
Open Access
- 1 February 1987
- journal article
- research article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 224 (3) , 675-684
- https://doi.org/10.1093/mnras/224.3.675
Abstract
A model for the clouds responsible for Lyman α absorption against distant quasars is presented in which the shape of the clouds is highly spheroidal instead of spherical. This gives a simple interpretation for the observed distribution of column densities at a given redshift found by Carswell, Webb, Baldwin & Atwood. Pressure equilibrium of the clouds with a hot intergalactic medium dense enough to account for the X-ray background is only possible if the clouds are either (i) maintained at around 105 K, (ii) only observed as they cool through 105 K or (iii) physically small, with a transverse size of a few pc.Keywords
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