University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Tuesday, December 3rd 2019
11:15 am:
Nuclear Physics Seminar in Tate 301-20
Speaker: Rafid Mahbub, UMN
Subject: Primordial black holes and second order gravitational waves from ultra slow-roll inflation models

The study of primordial black hole (PBH) formation has steadily gained
attraction ever since the first LIGO discovery of gravitational waves.
Although they are hypothetical objects, PBHs are relevant in the field
of cosmology because they are rather good candidates for cold dark
matter. I will talk about PBH formation through the perspective of
ultra slow-roll (USR) inflation models- particularly focusing on
inflationary α - attractors. An inflaton potential is created,
exhibiting a quasi-inflection point, where curvature perturbations are
enhanced. These give rise to high density fluctuations during the
radiation epoch, which can gravitationally collapse to form PBHs in
the mass range 10^16 – 10^18 g. It is around this mass range that PBHs
can comprise over 10% of the current cold dark matter energy density,
although recent analyses have somewhat relaxed observational
constraints there. I will also talk about second order gravitational
waves that can be generated and amplified around the 0.1 – 10 Hz
interval due to the influence of high curvature perturbations. The
energy density of such gravitational waves should lie within the
sensitivities of future detectors. I will end the talk with a
discussion on my future work on PBH formation, relying on the
stochastic inflation formalism.

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