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: http://xray.sai.msu.ru/sciwork/archive/111/eannot2.html
Дата изменения: Fri Jun 3 15:15:11 2005 Дата индексирования: Tue Oct 2 13:01:33 2012 Кодировка: Поисковые слова: massive stars |
We propose that the best sites to search for SGRs outside the Local group are galaxies with active massive star formation. Different possibilities to observe SGR activity from these sites are discussed. In particular we searched for giant flares from nearby galaxies (~2--4 Mpc) M82, M83, NGC 253, and NGC 4945 in the BATSE data. No candidates alike giant SGR flares were found. The absence of such detections implies that the rate of giant flares with energy release in the initial spike above 0.5x1044erg is less then 1/25 yr-1 in our Galaxy. However, hyperflares similar to the one of 27 December 2004 can be observed from larger distances. Nevertheless, we do not see any significant excess of short GRBs from the Virgo galaxy cluster and from galaxies Arp 299 and NGC 3256 with extremely high star formation rate. This implies that the galactic ra of hyperflares with energy release ~1046erg is less than ~10-3 yr-1. With this constraint the fraction of possible extragalactic SGR hyperflares among BATSE short GRBs should not exceed few percents. We present a list of short GRBs coincident with galaxies mentioned above, and discuss the possibility that some of them a hyperflares.