Sep 8 – 14, 2019
Toyama International Conference Center
Japan timezone

Enhancement of Gravitational Waves Induced by Scalar Perturbations due to a Sudden Transition from an Early Matter Era to the Radiation Era

Sep 12, 2019, 3:20 PM
20m
206 (Toyama International Conference Center)

206

Toyama International Conference Center

taup2019-sec@km.icrr.u-tokyo.ac.jp
Oral presentation in parallel session Cosmology Cosmology #3

Speaker

Dr Takahiro Terada (KEK)

Description

We study gravitational waves induced from the primordial scalar perturbations at second order around the reheating of the Universe. We consider reheating scenarios in which a transition from an early matter dominated era to the radiation dominated era completes within a timescale much shorter than the Hubble time at that time. We find that an enhanced production of induced gravitational waves occurs just after the reheating transition because of fast oscillations of scalar modes well inside the Hubble horizon. This enhancement mechanism just after an early matter-dominated era is much more efficient than a previously known enhancement mechanism during an early matter era, and we show that the induced gravitational waves could be detectable by future observations if the reheating temperature $T_{\text{R}}$ is in the range $T_\text{R}$ \lesssim $7\times 10^{-2} \, \text{GeV}$ or $20 \, \text{GeV}$ \lesssim $T_\text{R}$ \lesssim 2 $\times 10^7 \, \text{GeV}$. This is the case even if the scalar perturbations on small scales are not enhanced relative to those on large scales, probed by the observations of the cosmic microwave background. This talk will be based on our paper, arXiv:1904.12879.

Primary author

Dr Takahiro Terada (KEK)

Co-authors

Prof. Kazunori Kohri (KEK) Mr Keisuke Inomata (ICRR, The University of Tokyo) Dr Tomohiro Nakama (Hong Kong University of Science and Technology)

Presentation materials