射电噪活动星系核的γ射线探测

Research on the γ-ray Detection of Active Galactic Nuclei( AGNs)

本文通过交叉分析542个河外射电源样本,利用最新的费米LAT目录(3FGL)收集了80个相应的γ射线源,并调研了其多个参量之间的关系;所有的参数是直接观测所得或者是来源于相关文献。与非费米源相比,费米源的核主导参数平均值更大,红移反而更小。对于AGNs和星系来说,在固定的红移之下,费米源比非费米源有更高的本征的射电核流量。结果表明,费米源比非费米源有更加致密的结构;γ射线发射要受到喷流集束效应强有力的影响,核主导参数与多普勒因子是γ射线探测的重要指标。非费米源可能是由于更低的本征的射电核流量,或者是更低的本征的γ射线流量,这使得非费米源很难被费米LAT观测到。

80 radio sources with corresponding γ-ray emissions were identified by cross-correlating an archive of542 extragalactic radio sources with the latest data release（ Third Source Catalog 3FGL） by the Fermi LAT,and the correlations between multiple parameters were investigated; all the parameters were collected from available literature. Compared with non-Fermi sources,the Fermi sources have larger mean R values and smaller redshifts.For AGNs and galaxies,the Fermi sources have systematically larger radio flux than the non-Fermi counterparts at a given redshift. The results indicate that Fermi sources should be more compact and the strong beaming effect is vital for γ-ray emission,and that the core dominance parameter and Doppler factor are important probes for γ-ray detections. The non-Fermi sources are likely due to low intrinsic radio flux or the low intrinsic γ-ray flux or both,making them very difficult to be observed by Fermi LAT.