The Second Fermi-LAT AGN catalogue

摘要

The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The Second LAT AGN Catalog (2LAC) includes 1017 γ-ray sources located at high Galactic latitudes (|b| > 10deg) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. Consequently we define a Clean sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lacs), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars of unknown type (i.e., with broad-band blazar characteristics but with no optical spectral measurement yet), eight misaligned AGNs, four narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types and two starburst galaxies. The full characterization of the newly detected sources will require more broad-band data. Various properties, such as γ-ray fluxes and photon power law spectral indices, redshifts are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.