Gravitational waves and dark radiation from dark phase transition: Connecting NANOGrav pulsar timing data and hubble tension

Yuichiro Nakai, Motoo Suzuki, Fuminobu Takahashi, Masaki Yamada

Research output: Contribution to journalArticlepeer-review

Abstract

Recent pulsar timing data reported by the NANOGrav collaboration may indicate the existence of a stochastic gravitational wave background around f∼10−8 Hz. We explore a possibility to generate such low-frequency gravitational waves from a dark sector phase transition. Assuming that the dark sector is completely decoupled from the visible sector except via the gravitational interaction, we find that some amount of dark radiation should remain until present. The NANOGrav data implies that the amount of dark radiation is close to the current upper bound, which may help mitigate the so-called Hubble tension. If the existence of dark radiation is not confirmed in the future CMB-S4 experiment, it would imply the existence of new particles feebly interacting with the standard model sector at an energy scale of O(1 - 100) MeV.

Original languageEnglish
Article number136238
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume816
DOIs
Publication statusPublished - 2021 May 10

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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