Realisation of the ultra-slow roll phase in Galileon inflation and PBH overproduction
Choudhury S. Karde A. Panda S. Sami M.
1 July 2024Institute of Physics
Journal of Cosmology and Astroparticle Physics
2024#2024Issue 7
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.
cosmological perturbation theory , inflation , physics of the early universe , primordial black holes
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Centre For Cosmology and Science Popularization (CCSP), SGT University, Haryana, Gurugram, 122505, India
School of Physical Sciences, National Institute of Science Education and Research, Odisha, Bhubaneswar, 752050, India
Center for Theoretical Physics, Eurasian National University, Astana, 010008, Kazakhstan
Chinese Academy of Sciences, 52 Sanlihe Rd, Xicheng District, Beijing, China
Centre For Cosmology and Science Popularization (CCSP)
School of Physical Sciences
Center for Theoretical Physics
Chinese Academy of Sciences
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