Two BBL Talks On 10/28/2019 (Speakers: Julian Munoz, CFA, Harvard; Benny Tsang, University Of California, Santa Barbara)

Monday October 28, 2019 12:00 pm

Speaker #1 — Julian Munoz

Velocity-induced Acoustic Oscillations: A standard ruler at cosmic dawn
Abstract: I will describe how the 21-cm line acts as a standard ruler during cosmic dawn (z~20). The same acoustic physics that gives rise to the baryon acoustic oscillations produces a relative velocity between dark matter and baryons. These velocities impede the formation of the first stars during cosmic dawn, generating velocity-induced acoustic oscillations (VAOs) in the 21-cm power spectrum. I will show how these VAOs are immune to the unknown astrophysics of this era, and thus provide a robust standard ruler. By using VAOs, the upcoming HERA interferometer should be able to measure the Hubble expansion rate H(z) at z = 15 − 20 to percent-level precision, which can shed light on the H0 tension between supernovae and CMB observations.

Speaker #2 — Benny Tsang

Understanding the life and death of massive stars using numerical radiation hydrodynamics 
Abstract: In the most extreme sites of star formation – the nuclei of the densest and most massive star clusters, the intense radiation field carries significant momentum and has been suggested to control the dynamics of the star-forming gas and the overall efficiency of star formation. Following the detailed transport of radiation in hydrodynamical simulations can reveal multi-dimensional effects that would otherwise be lost in models assuming simple geometries. As massive stars approach the end of their lives and explode as core-collapse supernovae, radiation transport through the stellar ejecta also leaves informative imprints of the progenitor stars on the observed light curves and spectra. Reliably capturing the relevant radiative processes is instrumental to the proper inference of the progenitor’s stellar properties. In this talk, I will discuss how the application of Monte Carlo radiation transport in numerical simulations can help us understand the formation of massive star clusters and improve the interpretation of observed core-collapse supernova events.


  • Julian Munoz, CFA, Harvard University
  • Benny Tsang, University of California, Santa Barbara