高能天体物理研究组知识库

近期探测到Mrk 421和3C 454.3这两个耀变体(Blazar)在γ波段有强烈而显著的爆发,利用γ波段(GeV)和射电(15GHz)的流量数据对这两个源进行了详细分析,结果表明γ波段的光变与射电波段具有较强的相关性,且γ波段辐射光变超前于射电波段;我们讨论了可能的解释。另外,3C 454.3的射电辐射在2010年后的将近1 a时间内持续处于爆发状态,之后又出现一个较长时间的持续下降过程;在此期间,γ波段流量极低,表明其间喷流的活动性很弱,基本上不存在粒子的加速过程。因此,此持续下降过程可能表征辐射区的膨胀过程。

In this paper, the variabilities of Mrk 421 and 3C 454.3 are analyzed in detail. We collect the data in γ-ray (100MeV300 GeV) and radio (15 GHz) bands, and construct their light curves. Through analysis, we find that there is a strong correlation between γ-ray and radio fluxes, in which the variation in the γ-ray band leads that in radio band for two sources. The most likely explanation of the observed time lag is synchrotron opacity in the radiation region which could be optically thick to radio emission when the flares occur. Caused by the same perturbation, the radio and γ-ray flares at their peaks are not observed simultaneously due to the opacity effect. The radio flare is observed only when the emission region becomes optically thin. We also find a long time fall in the light curve of 3C 454.3 in radio band after a big outburst. In the same time, the γ-ray flux is very faint, indicating the weakness of the activity of the jet. We consider that the fall could correspond to an expanding process of the radiation region.