Refinements and improvements to a phenomenological model for the jet opening angles of gamma-ray bursts

Long duration gamma-ray bursts (GRBs) are thought to originate from the core collapse of massive, rapidly rotating stars - events called "hypernovae." In this thesis, we improve upon a phenomenological model to determine [theta], the jet opening angle of GRBs. We assume that hypernova progenitors are massive stars in binary systems. We calculate [theta] by equating two expressions for the probability of a given GRB being detected - one based on the geometry of the beaming model and the other based on the observed and expected rates of long duration GRBs. These expressions give [theta] as a function of several key physical parameters. We estimate these parameters, perform a Monte Carlo simulation, and obtain the most probable value of [theta] for both single and double jet GRB models. In contrast to previous work, we allow the minimum mass of star-forming galaxies to vary between 10⁶Mo and 10⁷Mo, and we calculate the galactic number density separately for three subtypes of spiral galaxies. For single jet and double jet models, we find that [theta] = 2.8+³.²-¹.². deg and [theta] = 1.9+².²-⁰.⁸. deg respectively. These results are somewhat lower than the results obtained in the earlier stages of this project [15, 16], but are in agreement with values inferred from the observed properties of GRBs [4]. Our results therefore support the assumption that massive binary stars are the progenitors of hypernovae that produce long-duration GRBs.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Tsitkin, Yelena

Advisor dc:contributor.advisor

• Paul C. Joss.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/114327

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/114327