Events Daily

Monday, December 4, 2023

Is the Milky Way disk two-dimensional?
David Hogg, New York University
Event Type: CCPP Brown Bag
Time: 12:30 PM - 1:30 PM
Location: 726 Broadway, 940, CCPP Seminar
Abstract: I discuss the empirical distribution of the elements as we see them represented in the surfaces of stars (in the SDSS-V data, which delivers a measurement of 15 element abundances in millions of stars). We want to use these measurements to learn about nucleosynthesis and nuclear physics. But the gastrophysics of the Milky Way plays a huge role too. I discuss all this, plus many near-term scientific opportunities.

Event Type: HEP Discussion Sessions
Time: 2:00 PM - 4:00 PM
Location: 726 Broadway, 902, Lg Conf

Analytic Model of Shock Cooling Emission Fitting In Core-collapse SNe
Jonathan Morag, Ben-Gurion University
Event Type: Informal Astro Talk
Time: 2:00 PM - 2:45 PM
Location: 726 Broadway, 940, CCPP Seminar
Abstract: We model shock-cooling emission in the first hours and days of core-collapse supernovae (SNe). A decade of fitting the observed emission to analytic models has shed light on the properties of the progenitor star, but despite its potential, fitting has also led to some inconsistent results, at times in disagreement with other measurement methods. We provide a frequency-dependent analytic formula for the spectral energy distribution (SED), derived from first principles, and carefully calibrated to multigroup numerical simulations with realistic opacity. We choose a simplified system with few free parameters. We span a large parameter space and show insensitivity to deviations from idealized ‘polytropic’ stellar structure. Recently in a systematic analysis of dozens of SNe, our model was used to show that ~70% of type II SNe are well described by simple shock-cooling, with progenitor radii consistent with observed RSG’s in the field. Apart from being a new scientific claim about the state of the progenitors, this result provides confidence in early-time emission fitting and in our method.