UNC-CH Physics and Astronomy Colloquium

Curtis McCully, Las Cumbres Observatory

“Transients in Time Domain Astronomy: Supernovae, Kilonovae, and Gravitational Lensing”

New technology in time-domain astronomy is transforming our understanding of the universe. High-cadence, wide-field time-domain surveys are discovering both rare and rapid transients, but discovery is only the first step: follow-up is key. Las Cumbres Observatory (LCO) operates a network of 21 robotic telescopes around the world which allows us to routinely get rapid, complete coverage of astronomical transients. Using LCO, we were able detect the first electromagnetic counterpart of a gravitational wave event produced by a neutron star merger even though the ensuing explosion, a “kilonova”, rose and faded in less than a week. I will present our observations from LCO and other spectroscopic facilities of the kilonova and discuss their implications for the amount of heavy r-process elements that were produced in this new type of cosmic explosion. We are also using LCO to observe other types of explosive transients. The Global Supernova Project is building a well-sampled spectroscopic and photometric dataset for an unprecedented sample of nearby supernovae. One class in this sample will be type Iax supernovae which are likely produced the “failed” explosion of a white dwarf with an exotic (helium-rich) donor. I will present our observations which led us to this physical picture including our detection in pre-explosion images which marks the first time the progenitor system of a white dwarf supernova has ever been observed. As future surveys like ZTF, LSST, and WFIRST begin, we will begin to be able to build samples of rare, exotic transients like gravitationally lensed supernovae which are poised to become novel, powerful tools for cosmology. Each of these types of transients, kilonovae and (lensed) supernovae, provide complementary constraints that we will use to probe the nature of dark matter and dark energy. I will discuss how we are preparing for future surveys so that we can utilize these cosmological probes to their full potential.