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Title: The rate of cosmic thermonuclear explosions in the Local Universe
Author: Frohmaier, Christopher M.
ISNI:       0000 0004 6497 4584
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2017
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This thesis investigates the volumetric rates of thermonuclear supernovae (SNe) in the Palomar Transient Factory (PTF). SN rates are a measure of how frequently stellar explosions occur as a function of cosmological volumes, or host galaxy properties. SNe are powerful cosmological probes; understanding their rates offers insight into the progenitors to the explosion and the astrophysics of galactic chemical evolution. The Palomar Transient Factory was an automated optical sky survey designed for transient discovery. It spectroscopically confirmed ~1900 SNe during the period of 2009-2012. PTF operated with a 3-5 day cadence, and scanned more than 8,000 square degrees of the sky. I quantified the performance of PTF through large scale simulations of transient events. Firstly, ~7 x 106 fake transient events were inserted into real observational images. These 'fakes' were designed to test the real-time transient discovery pipeline. The images were treated identically to a new PTF observation, where the fakes were either recovered or not. Multidimensional grids were created to describe how a transient would be recovered as a function of the fake's brightness and observing conditions. I found that bright fakes (mR < 18:5) were recovered with ~97% efficiency. PTF was 50% complete at mR = 20.3. The recovery efficiency was also strongly dependent on: the limiting magnitude, the image quality, the sky background, and the immediate environment brightness. The second stage of quantifying the performance of PTF was transient specific. Hundreds of millions of SNe Ia light curves were simulated on an artificial night sky. The simulations shared the statistical properties of the single epoch efficiencies. Through aMonte-Carlo simulation of the SNe Ia populations, I derived recovery efficiencies as a function of SNe Ia light curve parameters. A sample of 90 SNe Ia (z<0.09), were compared to the simulation recovery efficiencies. This provided the probability of the SNe passing rigorous quality cuts, and was used as a weighting factor.
Supervisor: Sullivan, Mark Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available