Properties of Unusually Luminous Supernovae

• Main Author: Pan, Tony Shih Arng
• Other Authors: Loeb, Abraham
• Language: en_US
• Published: Harvard University 2013
• Subjects: Astrophysics; Astronomy; Physics; supernova
• Online Access: http://dissertations.umi.com/gsas.harvard:10856; http://nrs.harvard.edu/urn-3:HUL.InstRepos:10947430

This thesis is a theoretical study of the progenitors, event rates, and observational properties of unusually luminous supernova (SN), and aims to identify promising directions for future observations. In Chapter 2, we present model light curves and spectra of pair-instability supernovae (PISNe) over a range of progenitor masses and envelope structures for Pop III stars. We calculate the rates and detectability of PISNe, core-collapse supernovae (CCSNe), and Type Ia SNe at the Epoch of Reionization with the James Webb Space Telescope (JWST), which can be used to determine the contribution of Pop III versus Pop II stars toward ionizing the universe. Although CCSNe are the least intrinsically luminous supernovae, Chapter 5 shows that a JWST survey targeting known galaxy clusters with Einstein radii > 35'' should discover gravitationally lensed CCSNe at redshifts exceeding z = 7–8. In Chapter 3, we explain the Pop II/I progenitors of observed PISNe in the local universe can be created via mergers in runaway collisions in young, dense star clusters, despite copious mass loss via line-driven winds. The PISN rate from this mechanism is consistent with the observed volumetric rate, and the Large Synoptic Survey Telescope could discover \(\sim10^2\) such PISNe per year. In Chapter 4, we identify 10 star clusters which may host PISN progenitors with masses up to 600M⊙ formed via runaway collisions. We estimate the probabilities of these very massive stars being in eclipsing binaries to be \(\gtrsim 30%\), and find that their transits can be detected even under the contamination of the background cluster light, due to mean transit depths of\(\sim10^6L\)⊙. In Chapter 6, we show that there could be X-ray analogues of optically superluminous SNe that are powered by the conversion of the kinetic energy of SN ejecta into radiation upon its collision with a dense but optically-thin circumstellar shell. We find shell configurations that can convert a large fraction of the SN explosion energies into X-ray emission, producing unabsorbed X-ray luminosities of \(10^{44}\) erg/s in events lasting a few months, or even \(10^{45}\) erg/s flashes lasting days. === Physics