Particle Physics Seminar: Probing Cosmic Dawn: From First Stars to New Physics

Abstract:

Recent and upcoming observations of the Cosmic Dawn and the Epoch of Reionization are opening new opportunities to study the earliest stars and galaxies, as well as physics beyond the Standard Model. In this talk, I will combine observations of high-redshift UV luminosity functions, the CMB optical depth to reionization, hydrogen absorption in quasar spectra, and the soft cosmic X-ray background to constrain the formation history and radiative properties of the earliest stellar populations. I will then show how these astrophysical constraints sharpen predictions for the global 21-cm signal during Cosmic Dawn and reveal the conditions under which Population III stars may produce a distinctive signature. By reducing astrophysical uncertainties, this framework also strengthens the role of the 21-cm signal as a probe of new physics, enabling potential beyond-the-Standard-Model signatures to be distinguished from otherwise degenerate astrophysical processes. As a concrete example we apply this framework to investigate a scenario in which non-gravitational interactions between the dark and visible sectors lead to additional cooling of the baryonic gas during Cosmic Dawn.

Seminar Organizer: Dr. Igor Korover