Realisation of the ultra-slow roll phase in Galileon inflation and PBH overproduction
Abstract
We demonstrate the explicit realisation of the ultra-slow roll phase in the framework of the effective field theory of single-field Galileon inflation. The pulsar timing array (PTA) collaboration hints at the scalar-induced gravity waves (SIGW) from the early universe as an explanation for the origin of the observed signal, which, however, leads to an enhancement in the amplitude of the scalar power spectrum giving rise to the overproduction of primordial black holes (PBHs). In the setup under consideration, we examine the generation of SIGW consistent with PTA (NANOGrav15 and EPTA) data, in addition to which we also consider the impact from QCD crossover at the nHz frequencies and address the PBH overproduction issue assuming linear approximations for the over-density without incorporating non-Gaussian effects from the comoving curvature perturbation. The framework is shown to give rise to SIGWs well consistent with the PTA signal with comfortable PBH abundance, 10-3 ≲ fPBH < 1, of near solar-mass black holes.
- Publication:
-
Journal of Cosmology and Astroparticle Physics
- Pub Date:
- July 2024
- DOI:
- 10.1088/1475-7516/2024/07/034
- arXiv:
- arXiv:2401.10925
- Bibcode:
- 2024JCAP...07..034C
- Keywords:
-
- cosmological perturbation theory;
- inflation;
- primordial black holes;
- physics of the early universe;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- General Relativity and Quantum Cosmology;
- High Energy Physics - Phenomenology;
- High Energy Physics - Theory
- E-Print:
- 62 pages, 23 figures, Comments are welcome, Revised version accepted for publication in JCAP