出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Blazars show intense and variable g -ray emission, and their properties have been investigated since the COS–B and CGRO era. Nevertheless, the AGILE and Fermi satellites are detecting recurrent flaring gamma-ray events from objects such as 3C 454.3 (the “Crazy Diamond”), 4C +21.35, 3C 273, and PKS 1510−089 which, for both their intensity and durations, are absolutely unique. This remarkable g -ray activity is a powerful tool to investigate the central regions of those sources, especially when combined with optical and X-ray data. On the other hand, such an unprecedented level of activity challenges the current theoretical models. We present the g -ray and multi-wavelength data collected so far, review the physical interpretations proposed for these extraordinary activity, and discuss the open points raised by these findings.
