Issue |
A&A
Volume 508, Number 1, December II 2009
|
|
---|---|---|
Page(s) | 107 - 115 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/20078905 | |
Published online | 15 October 2009 |
The number counts, luminosity functions, and evolution of microwave-selected (WMAP) blazars and radio galaxies*,**
1
ASI Science Data Center, ASDC c/o ESRIN, via G. Galilei, 00044 Frascati, Italy e-mail: cola@mporzio.astro.it
2
Agenzia Spaziale Italiana, Unità Osservazione dell'Universo, viale Liegi 26, 00198 Roma, Italy
3
on leave from: INAF – Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio, Italy
4
European Organisation for Astronomical Research in the Southern Hemisphere (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
5
Department of Physics, University of Perugia, via A. Pascoli, 06123 Perugia, Italy
Received:
23
October
2007
Accepted:
28
July
2009
We present an extensive search to identify the
counterparts of all the microwave foreground sources listed in the
WMAP 3-year catalogue using literature and archival data. Our work
has led to the identification of 309 WMAP sources, 98% of which
are blazars, radio quasars, or radio galaxies. Only 7 WMAP
detections were identified with other types of cosmic sources (3 starburst galaxies and 4 planetary/LBN nebulae). At present, 15 objects (<5%) still remain without identification because of
the unavailability of optical spectroscopic data or a clear radio
counterpart. Our results allow us to define a flux-limited sample
of 203 high Galactic latitude microwave sources ( Jy,
) that is virtually completely
identified (99%). The microwave band is ideally suited to blazar
statistical studies since this part of the electromagnetic
spectrum is least affected by the superposition of spectral
components of different origins, and therefore by selection
effects. Using this data-set, we derived number counts, luminosity
functions, and cosmological evolution of blazars and radio
galaxies at microwave frequencies. Our results are in good
agreement with those found at radio (cm) frequencies. The 5 GHz
bivariate blazar luminosity functions are similar to those derived
from the DXRBS survey, which shows that this sample is
representative of the blazar population at 41 GHz. Microwave selected broad-lined quasars are about six times more
abundant than BL Lacs, a ratio that is similar to, or larger than,
that seen at radio and gamma-ray frequencies, once spectral
selection effects are taken into account. This strongly suggests
that the mechanism responsible for the generation of gamma-rays
is, to first order, the same in all blazar types, leaving little
room for models (such as external Compton radiation) that predict
very different gamma-ray emission in broad-lined and lineless
blazars. Our results confirm, and strengthen on a more solid
statistical base, that blazars and radio galaxies are the largest contaminants of CMB anisotropy maps. We predict that these sources are also bright gamma-ray sources, most of which will be detected by the AGILE and
GLAST satellites.
Key words: galaxies: active / BL Lacertae objects: general / submillimeter / radio continuum: galaxies / surveys
© ESO, 2009
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