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Nucleosynthesis in the outflows associated with accretion disks of type II collapsars

Banerjee, Indrani and Mukhopadhyay, Banibrata (2013) Nucleosynthesis in the outflows associated with accretion disks of type II collapsars. In: Astrophysical Journal, 778 (1). 8_1-8_12.

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Official URL: http://dx.doi.org/10.1088/0004-637X/778/1/8


We investigate nucleosynthesis inside the outflows from gamma-ray burst (GRB) accretion disks formed by the Type II collapsars. In these collapsars, massive stars undergo core collapse to form a proto-neutron star initially, and a mild supernova (SN) explosion is driven. The SN ejecta lack momentum, and subsequently this newly formed neutron star gets transformed to a stellar mass black hole via massive fallback. The hydrodynamics and the nucleosynthesis in these accretion disks have been studied extensively in the past. Several heavy elements are synthesized in the disk, and much of these heavy elements are ejected from the disk via winds and outflows. We study nucleosynthesis in the outflows launched from these disks by using an adiabatic, spherically expanding outflow model, to understand which of these elements thus synthesized in the disk survive in the outflow. While studying this, we find that many new elements like isotopes of titanium, copper, zinc, etc., are present in the outflows. Ni-56 is abundantly synthesized in most of the cases in the outflow, which implies that the outflows from these disks in a majority of cases will lead to an observable SN explosion. It is mainly present when outflow is considered from the He-rich, Ni-56/Fe-54-rich zones of the disks. However, outflow from the Si-rich zone of the disk remains rich in silicon. Although emission lines of many of these heavy elements have been observed in the X-ray afterglows of several GRBs by Chandra, BeppoSAX, XMM-Newton, etc., Swift seems to have not yet detected these lines.

Item Type: Journal Article
Publication: Astrophysical Journal
Publisher: IOP Publishing Ltd
Additional Information: Copyright of this journal belongs to IOP Publishing Ltd.
Keywords: Accretion, Accretion Disks; Black Hole Physics; Gamma-Ray Burst: General; Nuclear Reactions, Nucleosynthesis, Abundances; Stars: Black Holes; Supernovae: General
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 30 Dec 2013 12:26
Last Modified: 30 Dec 2013 12:26
URI: http://eprints.iisc.ac.in/id/eprint/48059

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