The Redshift Distribution of Flat-Spectrum Radio Sources

Muñoz, J. A.; Falco, E. E.; Kochanek, C. S.; Lehár, J.; Mediavilla, E.
Bibliographical reference

The Astrophysical Journal, Volume 594, Issue 2, pp. 684-694.

Advertised on:
9
2003
Number of authors
5
IAC number of authors
1
Citations
21
Refereed citations
19
Description
The redshift distribution of flat-spectrum radio sources with 5 GHz flux densities S5>~5 mJy is a key component in using current radio lens surveys to probe the cosmological model. We have constructed the first flat-spectrum radio sample in the flux density range 3-20 mJy. Our new sample has 33 sources; we have determined the redshifts of 14 of these (42% complete). The low mean redshift, ~=0.75, of our faintest sample needs to be confirmed by further observations to improve the sample completeness. We also increased the redshift completeness of several surveys of brighter flat-spectrum sources. While the mean redshift ~=1.1 of flat-spectrum samples fainter than 1 Jy is nearly constant, the fraction of the sources identifiable as quasars steadily drops from ~80% to ~10% as the flux density of the sources decreases.