Institute for Fundamental Science

2024-25 Academic Year

Seminars, Colloquia, and Workshops

Organizer and host: Pouya Asadi

Unless otherwise noted, IFS seminars are Mondays at 4:00 p.m. in the IFS Seminar Room, 472 Willamette Hall.

A seminar announcement is distributed via email prior to each one. To add your name to the notification list, please email your request to Claire Staley, cnstaley@uoregon.edu.

To see prior years’ seminars, click here.

RECURRING ZOOM LINK

Spring Term 2025

Monday, April 14  4:00 – 5:00 pm   

The Power of the Dark Sink*

Speaker: Robert McGehee (University of Minnesota)

Abstract: I will describe a simple dark sector structure which, if present, has implications for the direct detection of dark matter (DM): the Dark Sink. A Dark Sink transports energy density from the DM into light dark-sector states that do not appreciably contribute to the DM density. As an example, I will consider a light, neutral fermion which interacts solely with DM via the exchange of a heavy scalar. I will illustrate the impact of a Dark Sink by adding one to a DM freeze-in model in which DM couples to a light dark photon which kinetically mixes with the Standard Model (SM) photon. I will check the contribution of the Dark Sink to dark radiation; consistency with existing data limits the maximum attainable cross section. For DM with a mass between 30 keV – 30 GeV, adding the Dark Sink can increase predictions for the direct detection cross section all the way up to the current limits.

*Time and interest permitting, I will shift gears for the last third of the talk to discuss an entirely different DM scenario in which WIMP-type DM has additional interactions that break baryon number. This leads to induced nucleon decays which are subject to direct experimental constraints from proton decay experiments. I will analyze the possibility of continuous baryon destruction, deriving strong limits from the dark matter accumulating inside old neutron stars, as such a process leads to excess heat generation.

Host: Ben Lillard

Monday, April 21  4:00 – 5:00 pm    

Expanding the diversity of tidal disruption events

Speaker: Jean Somalwar (Caltech)

Abstract: Tidal disruption events (TDEs) occur when a star is tidally shredded by a supermassive black hole (SMBH). They are a key probe of SMBH demographics and accretion physics. Optical surveys have been key for identifying TDEs, but searches have, until recently, relied on the properties of known TDEs to develop selection criteria, leading to TDE samples that likely suffer from significant selection effects. This talk will summarize efforts to expand the landsca  pe of TDEs using both radio and optical surveys. I will first discuss highlights from radio TDE searches – in particular, a sample of radio+optical TDEs that suggest that expanding our TDE searches may illuminate fundamentally different (lower mass, gas-rich) systems. I’ll then discuss ongoing efforts to expand our optical TDE selection, and highlight a newly discovered, offset, flaring IMBH candidate.

Host: Yvette Cendes

Monday, April 29  4:00 – 5:00 pm  **SPECIAL LOCATION: OMQ Conference Room WIL240D**

The Star Formation and Chemical Enrichment Histories of Galaxies in the Early Universe

Speaker: Charity Woodrum (NASA, Goddard Space Flight Center)

Abstract: One of the most active fields in modern astrophysics is galaxy evolution, with the goal to understand how the first galaxies formed and subsequently evolved across cosmic time. The launch of the James Webb Space Telescope (JWST) has enabled the study of the infant universe in unprecedented detail. In this talk, I will discuss the star formation and chemical enrichment properties of galaxies in the early universe using JWST observations. I will discuss the stellar mass assembly of galaxies and show that changing star formation parameters to reflect the higher temperatures in the infant universe is necessary to interpret JWST observations. As a byproduct of star formation, dust is one of the fundamental components of a galaxy. I will discuss the evolution of the dust content of galaxies and show some new findings that are one of the current challenges to explain.

Host: Yvette Cendes

Monday, May 5  4:00 – 5:00 pm

Phase Separation in Flocks, Herds and Swarms (Polar Active Fluids)

Speaker: Maxx Miller (UO)

Abstract: “Flocking” is the collective coherent motion of a large number of self-propelled entities (e.g., flocking of birds, schooling of fish, swarming of bees). Just as simple equilibrium fluids are described at large length and time scales by the Navier-Stokes equations, flocks also have a hydrodynamic description, known as the Toner-Tu equations.  Recently, we have extended these equations to account for strong attractive interactions between Flockers (which can arise from, e.g., autochemotaxis). We find that sufficiently strong attractive interactions cause the flock to phase separate into high- and low-density bands oriented parallel to the direction of mean-flock motion. This banding is reminiscent of ant trails, and the phase separation of the flock is in many ways analogous to equilibrium phase separation of simple fluids (i.e., the liquid-gas transition). However,  we have shown using the dynamical renormalization group that phase separation in flocks belong to a novel universality class, different from that of phase separation in simple equilibrium fluids.

Host: Jayson Paulose

Monday, May 12  4:00 – 5:00 pm    

Demographics of the Dynamic Radio Sky

Speaker: Dillon Dong (NRAO)

Abstract: The upcoming VLA Sky Survey (VLASS) transient catalog features ~4,000 radio point sources that appeared (or disappeared) across 3 all-sky epochs spanning ~7 years. When published, this catalog will ~triple the number of known radio transients evolving on timescales from minutes to decades. These transients originate from a diverse range of astrophysical phenomena, including flares from highly-magnetized stars in the Milky Way, terminal explosions of massive stars in local-universe galaxies, and newly-launched jets from supermassive black holes at cosmological distances. In this talk, I will discuss our methods for identifying ~3 million sources among ~1 trillion pixels in VLASS, which we then distilled to find the ~4,000 transients. Additionally, I’ll present some simple techniques that can be used to identify and characterize radio transients using archival data instead of follow-up campaigns. These methods are scalable, and generalizable to a wide range of current and upcoming time-domain radio surveys. When applied to VLASS, they are enabling us, for the first time, to systematically characterize the demographics of the dynamic radio sky.

Host: Yvette Cendes

Tuesday, May 13  4:00 – 5:00 pm  **SPECIAL DAY**    

CLEW: towards a truly global SMEFT analysis

Speaker: Tom Tong (University of Siegen) 

Abstract:

Host: Graham Kribs

Monday, June 2 4:00 – 5:00 pm    

Real-time Anomaly Detection at the CMS Experiment

Speaker: Isobel Ojalvo (Princeton)

Abstract: During Run-3 at the LHC, the search for new physics has significantly expanded. Development of advanced algorithms for the Level-1 trigger, encompassing techniques such as Long-Lived Particles, Data Scouting, and Muon showers to ensure broad data selection at the CMS experiment. Here, we introduce CICADA (Calorimeter Image Convolutional Anomaly Detection Algorithm), a state-of-the-art, fully autonomous AI algorithm engineered to process LHC event data in real-time and trigger on anomalous topologies. Operating directly on the rawest recorded data – the calorimeter energy deposits – CICADA demonstrates sensitivity to Standard Model processes. It unveils potential for Beyond the Standard Model Physics, including the exploration of previously untapped phase space at the LHC. 

Host: Laura Jeanty