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Toward an Understanding of the Progenitors of Gamma-Ray Bursts

Citation

Bloom, Joshua Simon (2002) Toward an Understanding of the Progenitors of Gamma-Ray Bursts. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/GKHP-2K61. https://resolver.caltech.edu/CaltechETD:etd-01062003-061357

Abstract

The various possibilities for the origin ("progenitors") of gamma-ray bursts (GRBs) manifest in differing observable properties. Through deep spectroscopic and high-resolution imaging observations of some GRB hosts, I demonstrate that well-localized long-duration GRBs are connected with otherwise normal star-forming galaxies at moderate redshifts of order unity. Using high-mass binary stellar population synthesis models, I quantify the expected spatial extent around galaxies of coalescing neutron stars, one of the leading contenders for GRB progenitors. I then test this scenario by examining the offset distribution of GRBs about their apparent hosts making extensive use of ground-based optical data from Keck and Palomar and space-based imaging from the Hubble Space Telescope. The offset distribution appears to be inconsistent with the coalescing neutron star binary hypothesis (and, similarly, black-hole-neutron star coalescences); instead, the distribution is statistically consistent with a population of progenitors that closely traces the ultra-violet light of galaxies. This is naturally explained by bursts which originate from the collapse of massive stars ("collapsars"). This claim is further supported by the unambiguous detections of intermediate-time (approximately three weeks after the bursts) emission "bumps" which appear substantially more red than the afterglows themselves. I claim that these bumps could originate from supernovae that occur at approximately the same time as the associated GRB; if true, GRB 980326 and GRB 011121 provide strong observational evidence connecting cosmological GRBs to high-redshift supernovae and implicate massive stars as the progenitors of at least some long-duration GRBs. Regardless of the true physical origin of these bumps, it appears that all viable alternative models of these bumps (such as dust scattering of the afterglow light) require a substantial amount of circumburst matter that is distributed as a wind-stratified medium; this too, implicates massive stars. Also suggested herein are some future observations which could further solidify or refute the supernova claim. In addition to the observational and modeling work, I also constructed the Jacobs Camera (JCAM), a dual-beam optical camera for the Palomar 200-inch Telescope designed to follow-up rapid GRB localizations.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:black hole; cosmology; gravitational waves; neutrinos; neutron stars; novae; population III; stars; Type Ic supernova
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Astronomy
Awards:Everhart Distinguished Graduate Student Lecturer Award, 2002
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Kulkarni, Shrinivas R.
Group:Astronomy Department
Thesis Committee:
  • Harrison, Fiona A. (chair)
  • Djorgovski, George
  • Kamionkowski, Marc P.
  • Scoville, Nicholas Zabriskie
  • Kulkarni, Shrinivas R.
Defense Date:1 April 2002
Non-Caltech Author Email:jbloom (AT) cfa.harvard.edu
Funders:
Funding AgencyGrant Number
Fannie and John Hertz FoundationUNSPECIFIED
Record Number:CaltechETD:etd-01062003-061357
Persistent URL:https://resolver.caltech.edu/CaltechETD:etd-01062003-061357
DOI:10.7907/GKHP-2K61
Related URLs:
URLURL TypeDescription
https://doi.org/10.1046/j.1365-8711.1999.02437.xDOIArticle adapted for Chapter 2.
https://doi.org/10.1086/311682DOIArticle adapted for Chapter 3.
https://doi.org/10.1086/312059DOIArticle adapted for Chapter 4.
https://doi.org/10.1086/321398DOIArticle adapted for Chapter 5.
https://doi.org/10.1086/338893DOIArticle adapted for Chapter 6.
https://doi.org/10.1038/46744DOIArticle adapted for Chapter 7.
https://doi.org/10.1086/341551DOIArticle adapted for Chapter 8.
https://doi.org/10.1086/311655DOIArticle adapted for Chapter 9.
ORCID:
AuthorORCID
Bloom, Joshua Simon0000-0002-7777-216X
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:06 Jan 2003
Last Modified:21 Dec 2019 02:21

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