We study the possibility of producing axion dark matter (DM) via misalignment mechanisms in a non-standard cosmological era dominated by ultra-light primordial black holes (PBH). While the effect of PBH domination on the production of axion via vacuum misalignment is known assuming the PBH evaporation to proceed according to Hawking's semi-classical (SC) approximation, we go beyond these simplest possibilities to include kinetic misalignment of axion and backreaction effect of emitted particles on the PBH themselves, referred to as the memory-burden (MB) effect. We show that, depending upon the type of misalignment mechanism and PBH evaporation regime, the axion as well as PBH parameter space consistent with the observed DM relic changes significantly having interesting implications for axion detection experiments. PBH also offer complementary detection prospects via gravitational wave due to PBH density fluctuations and excess radiation due to emission of hot axions within reach of future cosmic microwave background experiments.
Non-Cold Dark Matter from Memory-Burdened Primordial Black Holes
Universitäts-Sternwarte, Ludwig-Maximilians-Universität München（慕尼黑大学天文台）；Max-Planck-Institut für Extraterrestrische Physik（马克斯·普朗克地外物理研究所）；Excellence Cluster ORIGINS（ORIGINS卓越集群）；Theoretische Natuurkunde & The International Solvay Institutes, Vrije Universiteit Brussel（布鲁塞尔自由大学理论物理与国际索尔维研究所）；Max-Planck-Institut für Physik（马克斯·普朗克物理研究所）；Arnold Sommerfeld Center, Ludwig-Maximilians-Universität（慕尼黑大学阿诺德·索末菲中心）；Fakultät Physik, Technische Universität Dortmund（多特蒙德工业大学物理学院）
Exploring memory-burdened primordial black holes with ultra-high-energy cosmic-rays
Gran Sasso Science Institute (GSSI)（格兰萨索科学研究所）；INFN-Laboratori Nazionali del Gran Sasso (LNGS)（意大利国家核物理研究院大萨索国家实验室）；Scuola Superiore Meridionale（南方高等学院）；INFN - Sezione di Napoli（意大利国家核物理研究院那不勒斯分部）
We investigate the production of QCD axion dark matter in a nonstandard cosmological era triggered by primordial black holes (PBHs) that fully evaporate before the onset of BBN. Even if PBHs cannot emit the whole axion cold dark matter abundance through Hawking radiation, they can have a strong impact on the dark matter produced via the misalignment mechanism. First, the oscillation temperature of axions reduces if there is a PBH dominated era, and second, PBH evaporation injects entropy to the standard model, diluting the axion relic abundance originally produced. The axion window is therefor…
The entropy production prior to BBN era is one of ways to prevent QCD axion with the decay constant $F_{a}\in[10^{12}{\rm GeV},10^{16}{\rm GeV}]$ from overclosing the universe when the misalignment angle is $θ_{\rm i}=\mathcal{O}(1)$. As such, it is necessarily accompanied by an early matter-dominated era (EMD) provided the entropy production is achieved via the decay of a heavy particle. In this work, we consider the possibility of formation of primordial black holes during the EMD era with the assumption of the enhanced primordial scalar perturbation on small scales ($k>10^{4}{\rm Mpc}^{-1}$…
