CGCA Seminars

Low-Frequency Radio Transients
Reshma Anna Thomas
Netherlands Institute for Radio Astronomy, University of Amsterdam

The low-frequency radio sky (<300 MHz) remains comparatively underexplored for fast and slow transients (~ microseconds to minutes), primarily due to strong propagation effects as well as instrumental challenges. However, this regime provides unique leverage on plasma environments and emission physics that are inaccessible at GHz frequencies. Fast radio bursts (FRBs) are extragalactic coherent transients with millisecond durations, often exhibiting sub-millisecond temporal structure. I will present detections of two FRBs at 150 MHz using beamformed searches with LOFAR, which place some of the most stringent constraints to date on free–free absorption in their local environments. In parallel, a new class of Galactic sources, long-period transients (LPTs), has recently emerged, characterized by emission on second-to-minute durations and periodicities spanning minutes to hours.

Title and abstract to be determined
Janeth Valverde
Marquette University

The abstract for this talk will be added as soon as it is made available.

Galaxy-Scale Gravitational Wave Detection: The MPTA and the Road Ahead
Dr. Matt Miles
Vanderbilt University

Gravitational waves are emitted across a vast spectrum of frequencies. Ground-based detectors such as LIGO/Virgo/KAGRA observe relatively high-frequency waves from compact object mergers, while at the other end of the spectrum, the inspirals of supermassive black hole binaries produce a low-frequency rumble detectable only with a galaxy-scale instrument. By monitoring the pulses emitted by millisecond pulsars distributed across the Milky Way, pulsar timing arrays construct such a detector, spanning thousands of light-years.

Title and abstract to be determined
Shanika Galaudage
Northwestern University

The abstract for this talk will be added as soon as it is made available.

Spin Signatures in Horizon-Resolved Images of LLAGN
Dr. Daniel Palumbo, Smithsonian Astrophysical Observatory
Harvard University

With the advent of the Event Horizon Telescope (EHT), near-horizon black hole imaging with sub-mm very-long-baseline interferometry (VLBI) is now routine for the two sources for which terrestrial VLBI is sufficient to resolve the black hole shadow: Messier 87* and Sagittarius A*. Since the first images of M87*, the theoretical analysis of these images has advanced a broad class of black hole spin tracers in horizon-resolving observations, all of which have complex interplay with the astrophysical conditions near the horizon. Meanwhile, space VLBI mission concepts such as the Black Hole Explorer aim to drastically improve the angular resolution available via sub-mm VLBI, resolving out the primary accretion disk image to isolate the strongly lensed "photon ring," which more robustly exposes black hole mass, spin, and viewing inclination to distant observers.

Title and abstract to be determined
Joaquin Duran
UTSA

The abstract for this talk will be added as soon as it is made available.

Title and abstract to be determined
Nick Conroy
IAA/CfA

The abstract for this talk will be added as soon as it is made available.

Title and abstract to be determined
Patrick Brady
Professor, University of Wisconsin-Milwaukee

The abstract for this talk will be added as soon as it is made available.

Title and abstract to be determined
Alexander W. Criswell
Vanderbilt University

The abstract for this talk will be added as soon as it is made available.

Title and abstract to be determined
Pratyasha Gitika
Postdoctoral Scholar, University of Wisconsin-Milwaukee

The abstract for this talk will be added as soon as it is made available.