EVOLUTION OF THE Lya HALOS AROUND HIGH-REDSHIFT RADIO GALAXIES

We have obtained the first constraints on extended Lya emission at z ~ 1 in a sample of five radio galaxies. We detect Lya emission from four of the five galaxies. The Lya luminosities range from 0.1-4 X 1043 erg s-1 and are much smaller than those observed for halos around higher redshift radio gal...

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Bibliographic Details
Published in:The Astrophysical journal 2009-03, Vol.694 (1), p.L31-L35
Main Authors: Zirm, Andrew W, Dey, Arjun, Dickinson, Mark, Norman, Colin J
Format: Article
Language:English
Online Access:Get full text
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Summary:We have obtained the first constraints on extended Lya emission at z ~ 1 in a sample of five radio galaxies. We detect Lya emission from four of the five galaxies. The Lya luminosities range from 0.1-4 X 1043 erg s-1 and are much smaller than those observed for halos around higher redshift radio galaxies. If the z 1 radio galaxies are the descendents of the z 2 radio galaxies, then their Lya luminosities evolve strongly with redshift as ~(1 + z)5. There do not appear to be strong correlations between other parameters, such as radio power, suggesting that this observed evolution is real and not an observational artifact or secondary correlation. We speculate that this evolution of luminous halos may be due to gas depletion (as gas cools, settles, and forms stars) accompanied by an overall rise in the mean gas temperature and a decrease in specific star formation rate in and around these massive galaxies.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/694/1/L31