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 $10^{10}~M_\odot$.
The axion is a well-motivated hypothetical particle that could account for dark matter. In strong magnetic fields, such as those surrounding neutron stars and magnetars, axions can convert into photons, a process that could, in principle, produce detectable electromagnetic signatures. Traditionally, searches have focused on the microwave (centimeter wave regime), corresponding to axion masses...
Blazars are a class of active galactic nuclei, supermassive black holes located at the centres of distant galaxies characterised by strong emission across the entire electromagnetic spectrum, from radio waves to gamma rays. Their relativistic jets, closely aligned to the line of sight from Earth, are a rich and complex environment, characterised by the presence of strong magnetic fields over...
The LUX-ZEPLIN (LZ) experiment features a dual-phase xenon time projection chamber designed to detect weakly interacting massive particles (WIMPs) with unprecedented sensitivity. Among its backgrounds, scintillation-only events are particularly challenging to study due to their small size and consequential poor spatial reconstruction; yet, they play a significant role by contributing to...
Dark photon is one of the candidates for cold dark matter, predicted by specific models of string theories and high-scale inflation models. Dark photons interact with ordinary photons via the coupling constant $\chi$. Owing to this interaction, the dark photons convert into millimeter-wave light at electromagnetic boundaries, such as the surface of a metal plate. The frequency of the...
String theory models generically lead to a large number of axion-like particles (ALPs), known as the string axiverse. I will discuss the possible astrophysical and experimental signatures of the string axiverse, and how the phenomenology of many ALP systems differs from that of a single ALP or axion.
