ASD Colloquium Series - Fall 2026
ASD Colloquium Series - Fall 2026
The Astrophysics Science Division colloquia occur on Tuesdays at 3:45 pm in a Hybrid format. For in person attendees, the colloquia will be held in building 34, room W150 (unless otherwise noted), with an opportunity to meet the speaker at 3:30 pm. Virtual attendees should use connection information in the calendar invites.
Below is the list of scheduled talks for this period. Confirmed speakers are shown in bold face, while tentatively scheduled speakers are listed in normal face.
Schedules from past colloquium seasons are available.
Contact: Scott C. Noble
| September | |
|---|---|
| Sep 22 | Special Location: B34, W120B Probing the gamma-ray sky on longer timescales Akash Anumarlapudi (UNC Chapel Hill) |
| Sep 29 | Special Location: B34, W120A/B The Resonant Structure of Galaxy Disks John Beckman (Instituto de Astrofísica de Canarias) |
| October | |
| Oct 6 | TBD Cole Miller (UMD) |
| Oct 20 | TBD Spencer Hulsey (UIUC) |
| November | |
| Nov 3 | TBD Patricia Fofie (UC Irvine) |
| Nov 10 | TBD Riccardo Arcodia (Harvard) |
| December | |
| Dec 15 | TBD Keigo Fukumura (James Madison University) |
| March | |
| Mar 9 | TBD David Coulter (STScI) |
Abstract
Gamma-ray bursts (GRBs) are usually observed to have active emission timescales of a few milliseconds to a few seconds. In addition, there are sources in which the emission lasts for multiple minutes to a few hours, the ultra-long GRBs (UL-GRBs), which currently push the stable timescale of the central engine powering the GRBs. GRB search pipelines exploit the short timescale (milliseconds to seconds) increase in the photon flux to discover GRBs. But this can decrease their detection sensitivity to slowly varying, long-lived (upwards of a few hours) emission from gamma-ray sources. In this talk, I will introduce our detection method that utilizes time-integrated images from the Swift Burst Alert Telescope to discover gamma-ray transients. This complements the current searches on high time-resolution data by expanding the detection timescales from a few minutes to multiple days. Using the archival data from the Swift observatory, I will introduce initial results from our search. In the remaining limited lifetime of Swift, I will also highlight the prospect of near-real-time discoveries.
Abstract
Disk galaxies such as the Milky Way represent more than half of the population of galaxies in the local universe. Among their most recognizable properties are their spiral arms and some two thirds of them have characteristic barred concentrations of their stellar populations. It is now classical astrophysics that the presence of stable long-lived arms can only be explained by the presence of a spiral density wave in the disk, strongly stimulated by the bar. But theorists showed, around the turn of the millenium, that they could use the angular rotation speed of the bars in local galaxies to determine the predicted braking effect of dark matter halos on them, and when they did this they found that bars in general are rotating too fast. No evidence of the dark matter braking. Was there a basic flaw in the CDM cosmological scenario? In the talk I will explain how, in my group, we aimed to verify this, using a new technique to relate the internal kinematics of bars and arms to the dynamics of the rotating galaxies. We found a compex, but surprisingly elegant resonant structure in disks, and resolved the problem of the bars spinning too quickly. I will end by showing how our technique has probed the history of the dynamical interaction of M51 with its satellite galaxy NGC 5195.