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The many facets of cosmic explosions

Citation

Soderberg, Alicia Margarita (2007) The many facets of cosmic explosions. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-05252007-140338

Abstract

Over the past few years, long-duration gamma-ray bursts (GRBs) including the subclass of X-ray flashes (XRFs) have been revealed to be a rare variety of Type Ibc supernova (SN Ibc). While all these events result from the death of massive stars, the electromagnetic luminosities of GRBs and XRFs exceed those of ordinary Type Ibc SNe by many orders of magnitude. The observed diversity of stellar death corresponds to large variations in the energy, velocity and geometry of the explosion ejecta. Using multi-wavelength (radio, optical, X-ray) observations of the nearest GRBs, XRFs, and SNe Ibc, I show that GRBs and XRFs couple at least 10^48 erg to relativistic material while SNe Ibc typically couple less than 10^48 erg to their fastest (albeit non-relativistic) outflows. Specifically, I find that less than 3% of local SNe Ibc show any evidence for association with a GRB or XRF. Interestingly, this dichotomy is not echoed by the properties of their optical SN emission, dominated by the radioactive decay of Nickel-56; I find that GRBs, XRFs, and SNe Ibc show significant overlap in their optical peak luminosity and photospheric velocities. Recently, I identified a new class of GRBs and XRFs that are under-luminous in comparison with the statistical sample of GRBs. Owing to their faint high energy emission, these sub-energetic bursts are only detectable nearby (z < 0.1) and are likely 10 times more common than cosmological GRBs. In comparison with local SNe Ibc and typical GRBs/XRFs, these explosions are intermediate in terms of both volumetric rate and energetics. Yet the essential physical process that causes a dying star to produce a GRB, XRF, or sub-energetic burst, and not just a SN, remains a crucial open question. Progress requires a detailed understanding of ordinary SNe Ibc which will be facilitated with the launch of wide-field optical surveys in the near future.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:gamma-ray bursts; supernovae
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Astronomy
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Kulkarni, Shrinivas R.
Thesis Committee:
  • Phinney, E. Sterl (chair)
  • Harrison, Fiona A.
  • Ellis, Richard S.
  • Kulkarni, Shrinivas R.
  • Sargent, Wallace L. W.
Defense Date:18 May 2007
Author Email:ams (AT) astro.caltech.edu
Record Number:CaltechETD:etd-05252007-140338
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-05252007-140338
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2071
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:31 May 2007
Last Modified:26 Dec 2012 02:46

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