High-frequency predictions for number counts and spectral properties of extragalactic radio sources. New evidence of a break at mm wavelengths in spectra of bright blazar sources

Abstract

We present models to predict high-frequency counts of extragalactic radio sources using physically grounded recipes to describe the complex spectral behaviour of blazars that dominate the mm-wave counts at bright flux densities. We show that simple power-law spectra are ruled out by high-frequency (ν ≥ 100 GHz) data. These data also strongly constrain models featuring the spectral breaks predicted by classical physical models for the synchrotron emission produced in jets of blazars. A model dealing with blazars as a single population is, at best, only marginally consistent with data coming from current surveys at high radio frequencies. Our most successful model assumes different distributions of break frequencies, ν M , for BL Lacs and flat-spectrum radio quasars (FSRQs). The former objects have substantially higher values of ν M , implying that the synchrotron emission comes from more compact regions; therefore, a substantial increase of the BL Lac fraction at high radio frequencies and at bright flux densities is predicted. Remarkably, our best model is able to give a very good fit to all the observed data on number counts and on distributions of spectral indices of extragalactic radio sources at frequencies above 5 and up to 220 GHz. Predictions for the forthcoming sub-mm blazar counts from Planck, at the highest HFI frequencies, and from Herschel surveys are also presented.

Long-term variability of extragalactic radio sources in thePlanckEarly Release Compact Source Catalogue

“…The ERCSC data points displayed here are again the ERCSC 30 GHz flux densities extrapolated to the Ka-band central frequency. Although they vary from year to year, our source counts are largely consistent with the prediction of extragalactic radio source evolutionary models from de Zotti et al (2005) and Tucci et al (2011). The departure of the data from the models suggests that our sample is incomplete below 2 Jy.…”

Planck2013 results. XXI. Power spectrum and high-order statistics of thePlanckall-sky Compton parameter map

“…7.1 as a solid red line. Tucci et al (2011) model, fitted to the Planck ERCSC (Planck Collaboration Int. VII 2013), for extragalactic radio sources.…”

Cosmology with the cosmic microwave background temperature-polarization correlation

“…We computed the expectation at each cross-frequency for the point source amplitudes (a radio ν i ,ν j for the radio sources and a IR ν i ,ν j for the infrared sources) based on the flux-cut considered for our own point sources masks (see Sect. 2.1) using the model from Tucci et al (2011) for the radio sources and from Béthermin et al (2012) for dusty galaxies (see Table 4). We note that we found different prediction numbers for radio galaxies than those reported in Table 17 of Planck Collaboration XI (2016).…”

“…Poisson amplitudes for radio galaxies (model from Tucci et al 2011) and dusty galaxies (model from Béthermin et al 2012) compared to HiLLiPOP results. Units: Jy 2 sr −1 (νI ν = const.).…”