UCLA Dark Matter 2025

Session

SESSION 8: Dark Matter Theory

25 Mar 2025, 13:30

UCLA Physics and Astronomy Building 1-425

49. Cosmic Millicharge Background and Reheating Probes

Yu-Dai Tsai (University of California, Irvine)

25/03/2025, 13:30

Talk

We demonstrate that the searches for dark sector particles can provide probes of reheating scenarios, focusing on the cosmic millicharge background produced in the early universe. We discuss two types of millicharge particles (mCPs): either with, or without, an accompanying dark photon. These two types of mCPs have distinct theoretical motivations and cosmological signatures. We discuss...

45. Axions and the formation of supermassive black holes at cosmic dawn

Pierre Sikivie

25/03/2025, 13:45

Talk

Axion dark matter thermalizes by gravitational self-interactions and forms a Bose-Einstein condensate. It is shown that the rethermalization of the axion fluid during the initial collapse of large scale overdensities at cosmic dawn transports angular momentum outward sufficiently fast that black holes form with masses ranging from approximately $10^5$ to a few times $10^{10}~M_\odot$.

207. Dark matter halos at z > 6 through gas kinematics

John Silverman

25/03/2025, 14:00

Talk

NA

145. Macroscopic dark matter: fermi balls and black holes

zachary picker (UCLA)

25/03/2025, 14:45

Talk

I will discuss the formation of macroscopic dark matter from interacting dark sectors. Specifically,Fermi balls can form in dark sectors with a heavy fermion and a light scalar mediated Yukawa force. I'll discuss the behavior of these Fermi balls and the conditions under which they will collapse to form primordial black holes. Based on arXiv:2411.17074.

208. Gravitational Waves from Black Hole formation

Chris Kouvaris

25/03/2025, 15:00

Talk

In an early matter phase of the Universe, perturbations can
grow and lead to the formation of primordial black holes that can account
fully or partially for the observed dark matter abundance. During
formation, such primordial black holes can produce gravitational waves
that can be detected in interferometers or in Pulsar Timing Arrays. I'll
present results from numerical simulations...

155. Probing Gravothermal Collapse of Dark Matter Halos: Observational Insights

Hai-Bo Yu (University of California Riverside)

25/03/2025, 15:30

I will discuss the probing of gravothermal collapse of dark matter halos through stellar streams and strong lensing systems.

31. Q-balls with an Attractive Force

Philip Lu (KIAS)

25/03/2025, 15:45

Talk

We consider the Friedberg-Lee-Sirlin Q-ball with a renormalizable cubic interaction. This attractive Yukawa interaction balances the quartic interaction and results in more compact Q-balls with a maximum stable charge. We show that our numerical simulations match our analytic calculations of the maximum charge. Additionally, we consider the fate of these unstable Q-balls with excess charge,...