Astronomy and Astrophysics – Astronomy
Scientific paper
Jan 1977
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1977a%26a....54..475g&link_type=abstract
Astronomy and Astrophysics, vol. 54, no. 2, Jan. 1977, p. 475-484.
Astronomy and Astrophysics
Astronomy
28
Cosmology, Extragalactic Radio Sources, Galactic Evolution, Quasars, Radio Galaxies, Astronomical Models, Elliptical Galaxies, Luminous Intensity, Radio Astronomy
Scientific paper
The paper introduces the problem of radio source counts (log N-log S) and its relation to the problem of optical identification of radio sources. Two samples of radio sources complete to 10 and 0.9 Jy at 408 MHz, respectively, are presented for which optical identifications have been carried out as far as possible. An evolutionary model for radio sources is examined in which quasars and radio galaxies are linked in a single evolutionary sequence. A very good fit to the data is obtained by assuming that: (1) at z = 2.5 all the radio sources are born as quasars, with a quasar essentially a superactive nucleus of a giant elliptical galaxy; (2) the number of quasars per unit volume goes down exponentially with cosmological time; and (3) when a quasar goes off, it does so only optically, leaving behind a radio galaxy which continues to live as a radio source for a time roughly proportional to the inverse of absolute radio power.
Grueff Gavril
Vigotti Mario
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