Galaxies and Cosmology Seminar

Om Gupta, The University of Texas at Austin

Love Knows No Distance, But FRBs Do: The propagation effects of Fast Radio Bursts

Fast Radio Bursts are millisecond duration, generally extragalactic radio transients, that were only discovered in 2007. Being electromagnetic pulses, they interact with the medium between the source and us, primarily through interactions with plasma and magnetic fields. Their observed morphology and spectrum retains valuable information about these interactions and about conditions at the source. In this seminar, I will connect and highlight the propagation effects suffered by FRBs at two scales: at Galactic ISM scales and in the near-progenitor environment (< 1 pc). Exciting applications in the host galaxy and Milky Way ISM will be emphasized, along with a recent remarkable discovery based on theory proposed at UT. Finally, I will discuss the physics of propagation in extreme environments near the source, whose potentially significant imprint on FRBs remains largely unexplored. The usefulness of laser-plasma interaction theory and kinetic particle-in-cell simulations to determining the near-source propagation will be underscored.

Emily Bregou, The University of Texas at Austin

Chaos at Cosmic Dawn: Modeling Stochasticity and Breaking Degeneracies in Galaxy Formation Theory

Context: JWST data reveals significant gaps in our understanding of galaxy formation at cosmic dawn.

Aims: Investigate whether incorporating stochasticity into galaxy formation models improves agreement with high-redshift galaxy observations compared to deterministic models.

Methods:
• Create a fully analytic, flexible model of galaxy formation including stochasticity as a function of redshift and galaxy properties such as halo mass and UV magnitude.

• Fit model to UV Luminosity Function measurements across cosmic time to uncover how stochasticity shapes galaxy evolution.

Expected Results:
• A fully analytic, flexible (and publicly available) model of galaxy formation, incorporating stochasticity that varies across time and in galaxies of different mass/brightness 

• Insight into the physical drivers of stochasticity

• Recommendations for observational strategies to most effectively constrain galaxy formation models with the James Webb and Roman Space Telescopes.