AAS 204th Meeting, June 2004
Session 63 Exploding Stars
Poster, Wednesday, June 2, 2004, 10:00am-7:00pm, Ballroom

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[63.14] Runaway Merger in a Dense Stellar Cluster as a Progenitor of Gamma-ray Burst

T. Ebisuzaki (RIKEN), J. Makino (Univ. of Tokyo), R. Yamazaki (Kyoto Univ.), H. Baumgardt (RIKEN), T. Matsubayashi (TOkyo Institute Tech.), K. Makishima (Univ. of Tokyo and RIKEN)

Dynamical simulations of dense star clusters in starburst galaxy M82 have revealed that massive stars sunk into the center of the cluster and merged with each other to form a supermassive star with the mass exceeding few thousand solar mass (Portegies Zwart et al 2004). The gravitational core collapse of such supermassive star is a good candidate of gamma-ray bust: GRB030329 is identified to Type Ic supernova SN2003dh (Kawabata et al. 2003), which is believed to be caused by stellar collapse of a massive star. Since the supermassive star is likely to be a rapid rotator due to the angular momentum from the orbital angular momenta of accreted stars, its core collapse proceeds under the rotation dominant condition: A massive rotation supported accretion disk is formed around the black hole. This setup favors the formation of relativistic jets, which produces gamma-ray busts. Such an explosion by the collapse of a very massive star makes an intermediate mass black holes (IMBH) or ultra luminous X-ray source (ULXS), which are found in M82 and other star burst galaxies. This picture is consistent with the observation that some of those are rapidly rotating and show the nature of Kerr black holes.

The author(s) of this abstract have provided an email address for comments about the abstract: ebisu@postman.riken.go.jp

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