Institute for Advanced Study/Princeton University Early Universe/Cosmology Lunch Discussion
Topic 1: Is the Stellar Initial Mass Function Truly Universal? Topic 2: A Stimulating Explanation of the Extragalactic Radio Excess
Abstract 1: Current techniques for analyzing large photometric catalogs are generally forced to assume a single, universal stellar initial mass function (IMF), although the IMF should be expected to vary depending upon conditions within a star-forming galaxy. The introduction of an additional parameter into photometric template fitting allows galaxies to be fit with a range of different IMFs. Most galaxies are best fit with a bottom-lighter IMF than the Milky Way, and this change in IMF also modifies inferred properties such as stellar mass and star formation rate. Several surprising new features appear, including significant constraints on the feedback mechanisms responsible for star formation and subsequent quenching. I will also include a brief overview of an unrelated project, a possible reinterpretation of the current Hubble tension based on measurement uncertainties in supernova host redshifts.
Abstract 2: Current measurements of the diffuse radio monopole reveal a surface brightness that is several times higher than what can be explained by known Galactic and extragalactic sources and processes. In this talk I will briefly describe a simple model consisting of Axion-like particles (ALPs) Dark Matter and Dark photons (DPs) which can provide an exquisite solution to the longstanding radio background excess.