The number counts, luminosity functions, and evolution?of microwave-selected (WMAP) blazars and radio galaxies

摘要

We present an extensive search to identify thecounterparts of all the microwave foreground sources listed in theWMAP 3-year catalogue using literature and archival data. Our workhas led to the identification of 309WMAP sources, 98% of whichare blazars, radio quasars, or radio galaxies. Only 7WMAPdetections were identified with other types of cosmic sources(3starburst galaxies and 4planetary/LBN nebulae). Atpresent, 15objects (<5%) still remain without identificationbecause ofthe unavailability of optical spectroscopic data or a clear radiocounterpart. Our results allow us to define a flux-limited sampleof 203high Galactic latitude microwave sources (Jy, 15^circ$ -->)that is virtually completelyidentified(99%). The microwave band is ideally suited to blazarstatistical studies since this part of the electromagneticspectrum is least affected by the superposition of spectralcomponents of different origins, and therefore by selectioneffects. Using this data-set, we derived number counts, luminosityfunctions, and cosmological evolution of blazars and radiogalaxies at microwave frequencies. Our results are in goodagreement with those found at radio(cm) frequencies. The5GHzbivariate blazar luminosity functions are similar to those derivedfrom the DXRBS survey, which shows that this sample isrepresentative of the blazar population at 41GHz. Microwaveselected broad-lined quasars are about six times moreabundant than BL Lacs, a ratio that is similar to, or larger than,that seen at radio and gamma-ray frequencies, once spectralselection effects are taken into account. This strongly suggeststhat the mechanism responsible for the generation of gamma-raysis, to first order, the same in all blazar types, leaving littleroom for models (such as external Compton radiation) that predictvery different gamma-ray emission in broad-lined and linelessblazars. Our results confirm, and strengthen on a more solidstatistical base, that blazars and radio galaxies are the largestcontaminants of CMB anisotropy maps. We predict that these sources arealso bright gamma-ray sources, most of which will be detected by theAGILE andGLAST satellites.Key words: galaxies: active - BL Lacertae objects: general - submillimeter - radio continuum: galaxies - surveys