1. Primordial Black Holes and Second-order Gravitational Waves in Axion-like Hybrid Inflation
- Author
-
Ahmed, Waqas, Ghoshal, Anish, and Zubair, Umer
- Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics ,General Relativity and Quantum Cosmology ,High Energy Physics - Phenomenology ,High Energy Physics - Theory - Abstract
We investigate the possibility that primordial black holes (PBHs) can be formed from large curvature perturbations generated during the waterfall phase transition in a hybrid inflation model driven by an axion-like particle (ALP) $\phi$. The model predicts a spectral index $n_s \simeq 0.964$ and a tensor-to-scalar ratio $r \simeq 0.003$, in agreement with Planck data and potentially testable by next generation cosmic microwave background (CMB) experiments such as CMB-S4 and LiteBIRD. We find that the PBH mass and the peak of the associated scalar-induced gravitational wave (SIGW) spectrum are correlated with the ALP mass. In particular, PBHs in the mass range $10^{-13}\, M_\odot$ can constitute either the entire dark matter (DM) content of the universe or a significant fraction of it. The predicted second-order GWs from this mechanism are within the sensitivity reach of future observatories like LISA and ET. The typical reheating temperature in the model is around $10^6 - 10^7$ GeV is consistent with Big Bang Nucleosynthesis (BBN) constraints., Comment: 18 pages, 5 figures + Refs
- Published
- 2024