Probing White-Dwarf Explosions

Curtis McCully, PhD; Las Cumbres Observatory

Abstract:  The thermonuclear explosion of a white dwarf marks the death of a star, producing a type Ia supernova. The brightness of these supernovae can fortuitously be calibrated, allowing us to infer their distances, the technique that led to the Nobel Prize-winning discovery of the universe's accelerating expansion driven by “Dark Energy.” Despite this success, the explosion mechanism of type Ia supernovae is not fully understood. I will present several methods we employ to study these objects. With the advent of large time-domain surveys, we are discovering that there is a wide variety of ways that white dwarfs can explode. I will present the discovery of the first progenitor of a white-dwarf supernova in pre-explosion imaging and the bound remnant left over from the explosion. I will also present how early-time observations of type Ia supernovae can be used to search for signatures of the companion star in the explosion. This and other time-sensitive phenomena led us to develop the fully robotic network of telescopes, Las Cumbres Observatory. The next phase of this idea is UVIa, a proposed cubesat project in partnership with the University of Iowa that will be a dedicated mission to observe type Ia supernovae in the UV, searching for signatures of non-degenerate companion stars and characterizing the Far-UV, a previously unexplored regime. Understanding the details of white dwarf explosion physics has the potential to reduce the systematic uncertainties in type Ia supernova distances, which are the current limit on supernova cosmology.
 

Bio:  Curtis McCully is a Senior Astrodata Scientist at Las Cumbres Observatory. He finished his PhD at Rutgers, the State University of New Jersey in 2014 on observations of peculiar thermonuclear supernovae and gravitational lensing theory. He took a postdoc fellowship at Las Cumbres Observatory, working on a variety of explosive transients, including type Ia supernovae. He is a leader in the gravitational-wave follow-up group, which co-discovered the first confirmed kilonova in 2017. In his current position, McCully bridges the gap between scientists and software engineers, opening new capabilities in time-domain astronomy by developing data reduction pipelines and building interfaces for scientists and their data. He is also the Project Scientist for the proposed cubesat mission, UVIa.