
TY  - JOUR
A1  - Francis, Paul J. 
A1  - Wilson, Greg M. 
A1  - Woodgate, Bruce E. 
T1  - On the Gas Surrounding High-Redshift Galaxy Clusters
JF  - Publications of the Astronomical Society of Australia
JO  - Publ. Astron. Soc.  Aust.
Y1  - 2001
VL  - 18
IS  - 1
SP  - 64
EP  - 75
KW  - galaxies: clusters: individual (2142&#8211; 4420) &#8212; galaxies: distances and redshifts &#8212;quasars: absorption lines
UR  - https://doi.org/10.1071/AS01005 
N2  - Francis &amp; Hewett (1993) identified two 10 Mpc-scale regions of the high-redshift universe that were seemingly very overdense in neutral hydrogen. Subsequent observations showed that at least one of these gas-rich regions enveloped a cluster of galaxies at redshift 2 &#183;38. We present improved observations of the three background QSOs with sightlines passing within a few Mpc of this cluster of galaxies. All three QSOs show strong neutral hydrogen absorption at the cluster redshift, suggesting that this cluster (and perhaps all high-redshift clusters) may be surrounded by a &#126;5 Mpc-scale region containing &#126;10 12 M&ocir; of neutral gas. We show that if most high-redshift clusters are surrounded by such regions, the gas must be in the form of many small (&#60;1 kpc), dense (&#62; 0&#183;03 cm -3 ) clouds, each of mass &#60;10 6 M &ocir;. These clouds are themselves probably gathered into &#62;20 kpc-sized clumps, which may be galaxy halos or protogalaxies. If this gas exists, it will be partially photoionised by the UV background. We predict the diffuse Ly&#945; flux from this photoionisation, and place observational limits on its intensity. 
ER  -

