Published in "Extragalactic Background Radiation", Space
Telescope Science Institute Symposium Series 7, 1995, eds. D. Calzetti,
M. Livio and P. Madau
THE RADIO BACKGROUND: RADIO-LOUD GALAXIES
AT HIGH AND LOW REDSHIFTS
J. A. Peacock
Royal Observatory,
Blackford Hill, Edinburgh EH9 3HJ, UK
Abstract. This paper is in two unequal halves. After dealing with
the possibility of a
genuine continuum background at
λ
1 cm, and showing that
it is unlikely to arise in
interesting circumstances, the remainder of the discussion is devoted to
discrete radio
sources, and their consequences for cosmology. Three main issues are
considered: (i)
what makes a galaxy radio loud?; (ii) what do we know about how the
population of
radio-loud galaxies has changed with epoch?; and (iii) what can
observations of
high-redshift radio galaxies tell us about general questions of galaxy
formation and evolution?
The main conclusion is that radio galaxies are remarkably ordinary
massive ellipticals.
The high-redshift examples are generally old and red and do not make
good candidates for primeval galaxies.
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