Issue |
A&A
Volume 468, Number 2, June III 2007
The XMM-Newton extended survey of the Taurus molecular cloud
|
|
---|---|---|
Page(s) | 571 - 579 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20054160 | |
Published online | 13 March 2007 |
Swift detection of all previously undetected blazars in a micro-wave flux-limited sample of WMAP foreground sources
1
ASI Science Data Center, ASDC c/o ESRIN, via G. Galilei 00044 Frascati, Italy e-mail: paolo.giommi@asi.it
2
Agenzia Spaziale Italiana, Unitá Osservazione dell'Universo, via le Liegi, 26 00198 Roma, Italy
3
INAF - Osservatorio Astronomico di Roma via Frascati 33, 00040 Monteporzio, Italy
4
Department of Astronomy and Astrophysics, Pennsylvania State University, USA
5
Universitá di Roma “La Sapienza” Dipartimento di Fisica P.le A. Moro, 2 00185, Roma, Italy
6
INAF - Osservatorio Astronomico di Brera via Bianchi 46, 23807 Merate, Italy
7
Dipartimento di Fisica, Universitá di Perugia, via A. Pascoli, Perugia, Italy
8
UCL, Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
9
University of Southampton, Highfield, S017 1BJ Southampton, UK
10
NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
11
Department of Physics, University of Nevada, Las Vegas, NV 89154-4002, USA
Received:
6
September
2006
Accepted:
25
January
2007
Almost the totality of the bright foreground sources in the WMAP Cosmic
Microwave Background (CMB) maps are blazars, a class of sources that show usually also
X-ray emission. However, 23 objects in a flux-limited sample of 140 blazars of the WMAP catalog (first year) were never reported before as X-ray sources. We present here the
results of 41 Swift observations which led to the detection of all these 23 blazars in
the 0.3–10 keV band. We conclude that all micro-wave selected blazars are X-ray
emitters and that the distribution of the micro-wave to X-ray spectral slope () of
LBL blazars is very narrow, confirming that the X-ray flux of most blazars is a very good
estimator of their micro-wave emission. The X-ray spectral shape of all the objects that
were observed long enough to allow spectral analysis is flat and consistent with inverse
Compton emission within the commonly accepted view where the radiation from blazars is
emitted in a Sychrotron-Inverse-Compton scenario. We predict that all blazars and most
radio galaxies above the sensitivity limit of the WMAP and of the Planck CMB missions are
X-ray sources detectable by the present generation of X-ray satellites. An hypothetical
all-sky soft X-ray survey with sensitivity of approximately 10-15 erg cm-2 s-1 would be
crucial to locate and remove over 100 000 blazars from CMB temperature and polarization
maps and therefore accurately clean the primordial CMB signal from the largest population
of extragalactic foreground contaminants.
Key words: quasars: general / cosmology: cosmic microwave background / radiation mechanisms: non-thermal
© ESO, 2007
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