Past Colloquia
Astrophysical Lessons from LIGO-Virgo-KAGRA’s Black Holes
Cody Hall
Prof. Maya Fishbach
February 15, 2023
3:00pm - 4:00pm
The LIGO-Virgo-KAGRA Collaboration has observed over 70 gravitational-wave sources to date, including mergers between black holes, neutron stars, and mixed neutron star—black holes. Focusing on the black hole mergers, I will describe some recent lessons into how, when, and where black holes are made. These…
Milky Way Stellar Stream Heating
AB107, 50 St. George Street
Raymond Carlberg, University of Toronto
January 25, 2023
3:00pm - 4:00pm
A key prediction of LCDM is that galactic halos are filled with sub-halos orbiting within them, whereas warm dark matter models would have few. Studies of individual Milky Way star streams find evidence of a few sub-halos, but the sub-halo population properties are unclear. Current…
The Landscape of Relativistic Stellar Explosions
Cody Hall
Prof. Anna Ho, Cornell
January 18, 2023
3:00pm - 4:00pm
For the last half-century, relativistic outflows accompanying the final collapse of massive stars have predominantly been detected via high-energy emission, as long-duration gamma-ray bursts (GRBs). Yet, it has long been hypothesized that GRBs are the tip of the iceberg of relativistic stellar explosions, because the…
Direct Detection Searches for Low-Mass Dark Matter Particles
Cody Hall
Miriam Diamond
January 11, 2023
3:00pm - 4:00pm
The quest to unmask the fundamental nature of dark matter has inspired a vast worldwide program of complementary experiments, including direct-detection, indirect-detection, and collider searches.Direct-detection searches over the past few decades, using technologies such as large liquid noble chambers, have been largely focused on Weakly Interacting Massive Particles in…
Discovering the cold extrasolar planets with gravitational microlensing
Online Zoom
Prof. Shude Mao
December 07, 2022
11:00am - 12:00pm
Microlensing has become a powerful method to detect cold extrasolar planets beyond the snowline and free-floating planets. In this talk, I will first introduce the basic concepts of gravitational microlensing, review some of the recent discoveries with ongoing surveys, and then finish with a discussion…
The Far Ultraviolet diffuse background
AB 107, Codyhall
Shrinivas Kulkarni, Caltech
November 23, 2022
3:00pm - 4:00pm
Historically, the search for the inter-galactic medium(IGM) motivated the search for the Far Ultraviolet (FUV) backgroundwhich in turn led to a number of experiments and missions. Decadeslater the focus shifted to FUV as the primary heating and ionizingagent of the atomic phases (warm and cold…
A Golden Age of Asteroseismology with Kepler and TESS
Zoom
Tim Bedding
November 16, 2022
3:00pm - 4:00pm
Asteroseismology uses the natural oscillation modes of stars to study their interiors. The wonderfully precise measurements by NASA’s Kepler and TESS missions are ideal data sources for the technique. These space telescopes have been monitoring the brightness of hundreds of thousands of stars, with the…
Galaxy evolution in and around the circumgalactic bubble: New discoveries with CHaS and beyond
AB 107, Codyhall
David Schiminovich
November 02, 2022
3:00pm - 4:00pm
Despite tremendous progress in the 65 years since a possible interstellar “galactic corona” was first postulated, the study of warm-hot galactic atmospheres—now commonly referred to as the circumgalactic medium (CGM)—remains one of the last great baryonic frontiers in our developing census of the Universe. In…
Observing the hierarchical formation of our Milky Way
AB 107, Codyhall
Alan McConnachie, NRC Herzberg
October 26, 2022
3:00pm - 4:00pm
2024 will be the 30th anniversary of the discovery of the Sagittarius dwarf galaxy, the prototype and nonpareil of a galaxy in the process of being consumed by our Milky Way. It remains the most striking evidence for the ongoing hierarchical formation of galaxies in our…
Black holes and revelations: unseen companions in stellar binaries
AB 107, Codyhall
Kareem El-Badry
October 19, 2022
3:00pm - 4:00pm
The Milky Way contains of order 10^8 stellar-mass black holes (BHs). Yet, fewer than 100 BH candidates are known, and only about 20 are dynamically confirmed. Our view of the BH population has been shaped almost entirely by observations of X-ray binaries and gravitational wave…