Rapid variability in TeV blazars: the case of PKS 2155-304

被引：139
作者：
Ghisellini, G. [1 ]
Tavecchio, F. [1 ]
机构：
[1] INAF, Osservatorio Astron Brera, I-23807 Merate, Italy
来源：
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | 2008年 / 386卷 / 01期
关键词：
radiation mechanisms : general; galaxies : active; BL Lacertae objects : individual : PKS 2155-304; galaxies : jets; gamma-rays : observations;
D O I：
10.1111/j.1745-3933.2008.00454.x
中图分类号：
P1 [天文学];
学科分类号：
0704 ;
摘要：
Recent Cherenkov observations of BL Lacertae ( BL Lac) objects showed that the TeV ( teraelectron volt) flux of PKS 2155-304 changed by a factor of 2 in just 3 - 5 min. This fast variability can be accounted for if the emitting region is moving with a bulk Lorentz factor Gamma similar to 50 and a similar relativistic Doppler factor. If this Gamma is adopted, several models can fit the data, but, irrespective of the chosen model, the jet is matter dominated. The Doppler factor requires viewing angles of the order of 1 degrees or less: if the entire jet is as narrow as this, then we have problems with current unification schemes. This suggests that there are small active regions, inside a larger jet, moving faster than the rest of the plasma, occasionally pointing at us. Coordinated X- ray/ TeV variability can discriminate between the different scenarios.
引用
收藏
页码：L28 / L32
页数：5
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