Type Ia Supernovae

Diagram of the production of a Type Ia Supernova

Type Ia Supernovae occur when a white dwarf (or merging pair of white dwarfs) undergoes a runaway nuclear reaction and produces a brilliant stellar explosion. They are very important for a number of area of astrophysics, and I am particularly interested in their effects on nearby star formation and their use in cosmology. 


Pan-Starrs Telescope

Foundation Supernova Survey

Type Ia supernovae are important tools for measuring cosmological parameters. They serve as “standard candles” (and the small degree to which they fail to be can be quantified), giving us reference points throughout cosmic time that allow us to characterize the expansion history of the universe. This was first done by the High-z Supernova Search Team and the Supernova Cosmology Project in the 1990s, and they shared the Nobel Prize in Physics in 2011 for their work. As advances in astronomical instrumentation have been made, more low-z (z means redshift, so low-z means supernovae that are closer to us) supernovae have been discovered. Our constraints on dark energy are derived from comparisons between high-z and low-z samples (supernovae that are farther away and, consequently, occurred longer ago vs closer ones), so these low-z samples play an important role in cosmology. However, the existing low-z collection that is used in most analyses is collected from a variety of sources on a variety of telescopes. This heterogeneity leads to large systematic errors, and this proves to be the largest barrier to improvements in precision in the constraints on dark energy.

This is where the Foundation Supernova Survey comes in. Led by Ryan Foley (UCSC), Dan Scolnic (Chicago), and Armin Rest (STScI), this is a follow-up survey (meaning it follows already discovered supernovae instead of looking for new ones) on the Pan-STARRS telescope in Hawaii. Foundation has already acquired data for more low-z supernovae than the entire existing low-z sample, and it aims to compile a sample of 800 over the next few years to satisfy the cosmology goals of WFIRST. I worked with Ryan and Dan on this for the latter half of my undergraduate career, and the first data release has been published (Foley et al. 2018; see also Jones et al. 2018)


NIR Second Maximum

I also am working on better understanding the nature of the second maximum in NIR bands of supernova light curves. This feature complicates light curve template fitting, and, consequently, NIR bands are weighted against in light curve fitting suites. In order to gain a better understanding of this feature and allow for NIR bands to contribute more information to these fits, I am using the Open Supernova Catalog to quantify this particular feature using a number of statistical techniques in conjunction with spectral data. Results will be published shortly.