Radio Luminosity Function of Flat-spectrum Radio Quasars

MARCHESINI, E. J.; AJELLO, M.; URRY, C. M.; MASSARO, F.; MAO, P.; LANDONI, M.

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2017

0004-637X

We present the radio luminosity function (LF) of flat-spectrum radioquasars (FSRQ), using the the largest and most complete sample to date.Cross-matching between the FIRST 20 cm and GB6 6 cm radio surveys, wefind 638 flat-spectrum radio sources above 220 mJy at 1.4 GHz of these,327 are are classified and verified using optical spectroscopy data,mainly from Sloan Digital Sky Survey Data Release 12. We also consideredflat-spectrum radio sources that lack both literature references andoptical spectroscopy, and we identified 12 out of the 43 such sources topotentially be FSRQs, using their WISE colors. From the fully identifiedsample of 242 FSRQs, we derived the radio LF and cosmic evolution ofblazars at 1.4 GHz, finding good agreement with previous work at 5 GHz.The number density of FSRQs increases dramatically to a redshift of z∼ 2 and then declines for higher redshifts. Furthermore, theredshift at which the quasar density peaks is clearly dependent onluminosity, with more luminous sources peaking at higher redshifts. Theapproximate best-fit LF for a luminosity-dependent evolutionary model isa broken power-law with slopes ∼0.7 and ∼1.7 below and above thebreak luminosity, {log}{L}1.4∼ 43.8 ergs‑1, respectively.