APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: Kin-Wang Ng (Academia Sinica)
Title: 1. Production of high stellar-mass primordial black holes in trapped inflation / 2. Axion Dark Matter Induced Cosmic Microwave Background B-modes
Date (JST): Fri, Jan 27, 2017, 13:30 - 14:30
Place: Seminar Room B
Abstract: 1. Trapped inflation has been proposed to provide a successful inflation with a steep potential. We discuss the formation of primordial black holes in the trapped inflationary scenario. We show that primordial black holes are naturally produced during inflation with a steep trapping potential. In particular, we have given a recipe for an inflaton potential with which particle production can induce large non-Gaussian curvature perturbation that leads to the formation of high stellar-mass primordial black holes. These primordial black holes could be dark matter observed by the LIGO detectors through a binary black-hole merger. At the end, we have given an attempt to realize the required inflaton potential in the axion monodromy inflation, and discussed the gravitational waves sourced by the particle production.(based on arXiv:1606.00206)

2. We propose a new source of cosmic microwave background (CMB) B-mode polarization on sub-degree angular scales induced by dark matter density perturbation. If dark matter is ultra-light axion coupled to photon, its density fluctuations will induce cosmic birefringence fluctuations that would lead to a conversion of E-mode polarization of the CMB into B-mode polarization. We show that an allowed range of the coupling strength can produce B-mode polarization at sub-degree scales that can be observable in current and future CMB polarization experiments. These birefringence B modes may manifest as an excess power at high l in CMB lensing B-mode searches. (based on arXiv:1612.02104)