The origin of Gamma-Ray Bursts is one of the most interesting puzzles in recent astronomy. During the last decade a consensus formed that long GRBs (LGRBs) arise from the collapse of massive stars and that short GRBs (SGRBs) have a different origin, most likely neutron star mergers. A key ingredient of the Collapsar model that explains how the collapse of massive stars produces a GRB is the emergence of a relativistic jet that penetrates the stellar envelope. The condition that the emerging jet penetrates the envelope poses strong constraints on the system . Using these constraints we show that: (i) Low luminosity GRBs llGRBs, a sub population of GRBs with a very low luminosities (and other peculiar properties: single peaked, smooth and soft) cannot be formed by Collapsars . They have a different origin (most likely a shock breakout). (ii) On the other hand regular LGRBs must be formed by Collapsars . (iii) While for BATSE the dividing duration between Collapsars and non-Collapsar is indeed at ∼ 2 sec, the dividing duration is different for other GRBs detectors . In particular most Swift bursts longer than 0.7 sec are of a Collapsar origin. This last results requires a revision of many conclusions concerning the origin of Swift SGRBs which were based on the classical 2 sec limit.
|Original language||American English|
|Title of host publication||Proceedings of the 10th International conference on Gravitation, Astrophysics and Cosmology, ICGAC 2011|
|Editors||Roland Triay, Jean Tran Thanh Van, Ludwik M. Celnikier|
|Publisher||The Gioi Publishers|
|Number of pages||10|
|ISBN (Electronic)||6047706193, 9786047706198|
|State||Published - 2011|
|Event||10th International conference on Gravitation, Astrophysics and Cosmology, ICGAC 2011 - Quy Nhon, Viet Nam|
Duration: 15 Dec 2011 → 21 Dec 2011
|Name||Proceedings of the 10th International conference on Gravitation, Astrophysics and Cosmology, ICGAC 2011|
|Conference||10th International conference on Gravitation, Astrophysics and Cosmology, ICGAC 2011|
|Period||15/12/11 → 21/12/11|
Bibliographical noteFunding Information:
This research was supported by an Advanced ERC grant and by the Israeli center for Excellent for High Energy AstroPhysics (TP), by an ERC starting grant and an ISF grant (EN) and by Packard, Guggenheim and Radcliffe fellowships (RS).
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