Axion-like-particle (ALP) is a well-motivated candidate for dark matter, and it has been subject to extensive theoretical and experimental research in recent years. The most popular ALP production mechanism studied in the literature is the misalignment mechanism, where the ALP field has negligible kinetic energy initially, and it starts oscillating when its mass becomes comparable to the Hubble scale. In most of these studies, the ALP field has been assumed to be a homogeneous classical field, and its quantum fluctuations have been ignored. However a non-zero initial velocity can cause exponential growth in the amplitude of fluctuations, and most of the energy density in the homogeneous mode can be converted to axion particles, known as fragmentation. In this talk I will present a semi-analytical study of this process, and describe the necessary ingredients for an efficient fragmentation. I will also mention some observational prospects such as the halo spectrum.
|Collaboration / Activity||Quantum Universe|
|First author||Cem Eröncel|