Extended emission in short gammaray bursts registered by

Extended emission in short gamma-ray bursts registered by SPI-ACS of INTEGRAL observatory Pavel Minaev 1, 2, Alexei Pozanenko 1, Vladimir Loznikov 1 1 - Space Research Institute (Moscow, Russia) 2 - Moscow State University (Moscow, Russia)

GRB duration classification ≤

Data selection and analyzed groups of events Data selection: We have formed the list of short gamma-ray bursts, registered by SPI-ACS INTEGRAL in 2002 -2007, confirmed by other space-borne experiments (Swift, Konus, HETE etc), which consists of 86 events. Heavy particle triggers have been selected. Analyzed groups of events: Confirmed short GRBs from our catalog (hereafter shown by black color) Unconfirmed short GRBs with T 90<2 s (blue color) Unconfirmed short GRBs with T 90≤ 0. 05 s (green color) Heavy particle triggers (red color).

Data analysis Alignment of time profiles against main peak Approximation of background by a linear law Subtraction of background model from time profile Calculation of averaged time profile for each group of events.

Time profile of GRB 060221

Averaged time profiles of 2 groups of short events, registered by SPI-ACS INTEGRAL

Averaged time profiles of 2 groups of short events, registered by SPI-ACS INTEGRAL ≤

Log N – Log Cmax distribution - 3/2 ≤

Conclusions We have formed the list of short gamma-ray bursts, registered by SPIACS INTEGRAL in 2002 -2007, confirmed by other space-borne experiments (Swift, Konus, HETE etc), which consists of 86 events. The extended emission up to 25 s after main peak has been found in averaged light curves of both confirmed and unconfirmed short GRBs registered by SPI-ACS INTEGRAL in energy band >80 ke. V The extended emission of the GRBs registered by SPI-ACS is in energy range above ~80 ke. V which may evidence against of explanation of extended emission as a rise of the afterglow. The evidence for extended emission in averaged light curve of unconfirmed short duration events of SPI-ACS supports the same origin of unconfirmed events as short duration gamma-ray bursts and increases the rate of INTEGRAL short duration bursts in three times, and the portion of short burst may be up to 45% of all Gamma-Ray bursts detected by SPI-ACS. The extended emission in averaged light curve of unconfirmed short duration events with T 90≤ 0. 05 s of SPI-ACS may evidence against of explanation of these events as evaporations of primordial black holes and supports the assumption, that these events have the same origin as short duration gamma-ray bursts with T 90<2 s.