Past Events


A&A Colloquium: Kate Alexander (Northwestern University)

3:30–4:30 pm Zoom

“Cosmic Extremes: Time-Domain Astrophysics in a Multi-Messenger World”

Time-domain astrophysics provides a unique opportunity to study the most extreme physical processes in the Universe, including the deaths of massive stars, the destruction and creation of compact objects like neutron stars and black holes, and the tidal disruption of stars by supermassive black holes. I will discuss my recent and ongoing work to reveal the formation and structure of relativistic jets and outflows in the most extreme astrophysical transients, including gamma-ray bursts (GRBs) and tidal disruption events (TDEs). I will further show that radio data provide the best constraints on the immediate environments of these transients, probing models of black hole growth and accretion (TDEs) and stellar evolution models (GRBs). Finally, I will discuss the bright future of time-domain astrophysics. With the pioneering detections of gravitational waves, astronomers and physicists have gained a new, complementary tool to study compact object mergers, with implications for fields as wide-ranging as general relativity, nuclear physics, cosmology, and shock physics. Collaboration with LIGO and its successor gravitational wave observatories will enable precision constraints on merger physics, while wide-field surveys like DES and Rubin Observatory’s LSST will provide the first large samples of rare, relativistic events and move transient science into the statistical realm. Simultaneously, new radio interferometers like the ngVLA and the Square Kilometer Array together with high-cadence survey experiments like CMB-S4 are poised to transform radio astronomy, revealing the radio sky in unprecedented depth and leading to the discovery of relativistic transient populations in the radio band.

Feb 24

KICP Seminar: Djuna Croon (TRIUMF)

12:00–1:00 pm Zoom

Djuna Croon, TRIUMF, “New Physics and the Black Hole Mass Gap”

Feb 18

A&A Colloquium: Diana Powell (University of California, Santa Cruz)

3:30–4:30 pm Zoom

Connecting Planet Formation & Characterization

A fundamental understanding of planetary histories and characteristics requires an empirical connection between planet formation and evolved planets—a long-sought goal of astrophysics. This connection is now increasingly possible due to simultaneous revolutions in the observations of protoplanetary disks and exoplanet atmospheres. A key step towards relating these observations of different evolutionary stages is to characterize the composition of material in protoplanetary disks and relate these properties to the atmospheric composition of planets. In this talk, I will discuss initial steps that I have taken towards this goal. I will provide evidence that protoplanetary disks are more than an order of magnitude more massive than previously appreciated, that the detailed properties of clouds shape observations of substellar atmospheres, and that the physics of modeling clouds gives a new understanding of the compositional distribution in protoplanetary disks. I will conclude by discussing avenues for relating planetary properties to the compositional mass inventory in protoplanetary disks as a function of time in order to develop the observationally validated framework required to compositionally relate evolved planets to planet formation.

Feb 17

Outreach event: Mapping the Origins of the Universe

3:30–4:30 pm Zoom

Join C2ST as we connect with researchers LIVE from the NSF-funded telescope projects in the South Pole and Chile to unlock some great mysteries to the origin of the cosmos.

Feb 16

KICP Seminar: Anna-Christina Eilers (MIT)

12:00–1:00 pm Zoom

Anna-Christina Eilers, MIT, “The Formation and Growth of Supermassive Black Holes”

Feb 11

A&A Colloquium: Kareem El-Badry (University of California, Berkeley)

3:30–4:30 pm Zoom

“Better together: binary stars as probes of stellar evolution and fundamental physics”

Binary stars are foundational to modern astrophysics. They underpin precision measurements of stellar structure, age, and composition; they provide the most stringent tests of general relativity, they make possible the study of faint and rare objects such as black holes and neutron stars, and they are the progenitors of gravitational wave sources. The components of binaries often interact, dramatically changing their evolution and giving rise to a spectacular zoo of astrophysical phenomenology. To understand stars—particularly massive stars—it is necessary to understand binaries. Large-scale stellar surveys such as Gaia, TESS, and SDSS-V are transforming the binary field, making possible both comprehensive population demographics and the discovery of rare objects. I will discuss new insights gleaned from surveys in recent years, including the creation of stripped-envelope stars following binary mass transfer, the formation of equal-mass “twin” binaries in circumbinary disks, the metallicity-dependence of the binary fraction, and the discovery of planets in binaries. I will focus in particular on the search for dormant stellar-mass black holes in binaries, discussing recent candidates and the path forward to characterizing the detached black hole population.

Feb 10

Tuesday Lunch Seminar: Vikram Dwarkadas (UChicago)

12:00–1:00 pm Zoom

Triggered Star Formation Inside the Shell of a Wolf–Rayet Bubble as the Origin of the Solar System

Vikram Dwarkadas, UChicago

Feb 9

KICP Seminar: Suhail Dhawan (Stockholm/KICC, Cambridge)

12:00–1:00 pm Zoom

Suhail Dhawan, Stockholm/KICC, Cambridge, “Cosmology with Type Ia Supernovae: A View from the Zwicky Transient Facility”

Feb 4

A&A Colloquium: Anna Rosen (Harvard)

3:30–4:30 pm Zoom

The Destructive Birth of Massive Stars and Massive Star Clusters

Massive stars play an essential role in the Universe. They are rare, yet the energy and momentum they inject into the interstellar medium (ISM) with their intense radiation fields and fast, isotropic radiatively driven winds dwarfs the contribution by their vastly more numerous low-mass cousins. This stellar feedback dominates the energy and momentum budget in star-forming regions and galaxies leading to gas ejection, which has important implications for star and galaxy formation. Massive stars form from the gravitational collapse of magnetized, dense, and turbulent molecular gas in massive pre-stellar cores, which are located in highly embedded environments. During their formation, feedback from their intense radiation fields, collimated protostellar outflows, and stellar winds can limit their growth by accretion. In this talk, I will show a series of radiation-magnetohydrodynamic (RMHD) simulations of the collapse of massive pre-stellar cores into massive stellar systems that include these feedback processes to demonstrate how stellar feedback can limit accretion onto massive stars and disrupt their natal environments. In addition, I will also discuss how stellar feedback from massive stars, which are born in clustered environments, affects the dynamics of HII regions that surround these clusters and can drive ISM turbulence in young, star clusters. Finally, I will talk about the future of state-of-the-art RMHD simulations with the new “Star Formation in Gaseous Environments” (STARFORGE) framework that will study the formation of star clusters from the gravitational collapse of giant molecular clouds by including all of the relevant stellar feedback processes and are capable of resolving the formation of individual stars. Such simulations will facilitate unprecedented strides in our understanding of the importance of stellar feedback in star formation and to determine how the interaction of stars in gaseous environments affects stellar dynamics, clustering, and ejection of stars.

Feb 3

KICP Seminar: Giuseppe Puglisi, (University of California, Berkeley)

12:00–1:00 pm Zoom

Giuseppe Puglisi, University of California (Berkeley), “Extending Galactic Foreground Mmodels for CMB with Adversarial Networks”

Jan 28