Talks & Events
Special Seminars - Other talks that aren't Astronomy Colloquia or KICP Colloquia. Persons with a disability who believe they may need assistance, please call the departmental secretary in advance at 773-702-8203 or email deptsecoddjob.uchicago.edu.
Past Special Seminars
Engines, Lighthouses, and Laboratories: Massive Stars Across the Cosmos
Massive stars are crucial building blocks in the study of star-forming galaxies, stellar evolution, and transient events, and their applications as astrophysical tools span a broad range of subfields. The radiative signatures of young star-forming galaxies are powered by their massive stellar populations. Transient phenomena act as observational beacons, ranging from local non-terminal events signaling the death throes of extreme massive stars to long-duration gamma-ray bursts that can serve as powerful probes of the high-redshift universe. Finally, resolved massive star populations offer a treasure trove of nearby targets, allowing us to closely examine their physical parameters, evolution, and contribution to chemical enrichment. I will present my current research programs focused on developing a comprehensive picture of massive stars across the cosmos: observational surveys and models of star-forming galaxies, progenitor and host environment studies of transient phenomena, and extragalactic stellar observations, including the recent discovery of the first Thorne-Zytkow object candidate. Combined, this work will make substantial progress in our understanding of massive stars over the coming decade. This in turn will equip us with the tools we need to take full advantage of the frontiers opened up by new observational facilities such as the GMT, LSST, and JWST, allowing us to immediately begin probing the new corners of the universe that they reveal.
The End of Reionization: An IGM Perspective
The epoch of reionization was a period of intense interaction between luminous objects and their surroundings. Consequently, along with tracking the cosmic history of baryons, determining when and how the intergalactic medium (IGM) was reionized provides fundamental insights into the first stars and galaxies. I will describe a set of recent projects that examine reionization by using quasar absorption lines to probe the IGM at the highest observable redshifts. The results help to clarify when reionization ended and the role played by galaxies, but also pose significant challenges to current reionization models. I will describe the next steps forward, and some of the potential avenues for IGM science with next-generation observing facilities.
Transient Astronomy: Dark Energy, Supernova Physics & Exotica
We are currently in a golden age of transient astronomy. Repeated imaging of large areas of the sky have revealed celestial objects that change on a human timescale. LSST and WFIRST, the top ground-based and space-based priorities for the entire astronomical community, are inherently transient surveys. Because of these upcoming facilities combined with follow-up capabilities from upcoming facilities such as GMT, this field will continue to grow for the foreseeable future. Scientifically, transient astronomy holds significant potential for major discoveries. Supernovae are connected to almost every aspect of astrophysics from star formation to cosmic ray acceleration to dust formation to chemical enrichment and feedback. Type Ia supernovae remain one of our primary dark energy probes. New classes of exotic transients are revealing rare and extreme endpoints to stellar evolution.
I will discuss recent successes and potential future opportunities in transient astrophysics. These include a factor of 2 improvement in Type Ia supernova distances, a new survey to make the most headway in measuring dark energy, a large on-going Hubble program and the innovative use of light echoes from historical Galactic supernovae to measure the explosion properties of Type Ia supernovae, and a Magellan program to probe Type Ia supernova progenitor environments. I will also briefly discuss the recently identified Type Iax class of supernovae, which are the most common "peculiar" supernovae. I will present observations of the progenitor system of one Type Iax supernova, the first detection of a progenitor system for any thermonuclear supernova.