New type of long GRBs with additional maxima on the temporal profiles in the high energy gamma-band

Abstract

In the presented work the results of GRBs temporal profiles analysis in the high energy gamma-band are discussed. Now GRBs high energy gamma-emission was observed both during short and long bursts mostly by detectors onboard Fermi and Agile satellites. The duration of such emission is more than some hundreds seconds and sufficiently longer than t90 in the low energy band. But usually the maximum of high energy emission is in the t90 intervals. However the investigation of GRBs temporal profiles in the region E>100 MeV have shown the opportunity of new burst type separation. In the difference of usual GRBs, temporal profiles of new type of bursts in the high energy gamma-band have several characteristic features. For example, GRB090323, GRB090328 and GRB090626 temporal profiles have additional maxima after low energy t90 intervals finished. These bursts temporal profile analysis have shown that faint peaks in low energy bands close to the ends of low energy t90 intervals preceded these additional maxima. The analogues features were separated during some other GRBs by the results of preliminary data analysis, for example, GRB110721A and GRB100724B. We suppose that these GRBs could be considered as different GRB type. The temporal profiles and spectra characteristic properties of new type of bursts are discussed in this article.