TY - JOUR
T1 - Gravitational waves and dark radiation from dark phase transition
T2 - Connecting NANOGrav pulsar timing data and hubble tension
AU - Nakai, Yuichiro
AU - Suzuki, Motoo
AU - Takahashi, Fuminobu
AU - Yamada, Masaki
N1 - Funding Information:
We thank Kohei Fujikura, Marek Lewicki, and Graham White for pointing out the suppression factor for the sound-wave period. Y.N. would like to thank Kohei Fujikura and Keisuke Harigaya for discussions. Y.N. is grateful to Kavli IPMU for their hospitality during the COVID-19 pandemic. M.S. would like to thank Ryo Namba for discussions. This work was supported by JSPS KAKENHI Grant Numbers 17H02878 (F.T.), 20H01894 (F.T.), 20H05850 (F.T.), 20H05851 (F.T. and M.Y.) and JP20K22344 (M.Y.). F.T. was supported by World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan. M.Y. was supported by Leading Initiative for Excellent Young Researchers, MEXT, Japan.
Funding Information:
We thank Kohei Fujikura, Marek Lewicki, and Graham White for pointing out the suppression factor for the sound-wave period. Y.N. would like to thank Kohei Fujikura and Keisuke Harigaya for discussions. Y.N. is grateful to Kavli IPMU for their hospitality during the COVID-19 pandemic. M.S. would like to thank Ryo Namba for discussions. This work was supported by JSPS KAKENHI Grant Numbers 17H02878 (F.T.), 20H01894 (F.T.), 20H05850 (F.T.), 20H05851 (F.T. and M.Y.) and JP20K22344 (M.Y.). F.T. was supported by World Premier International Research Center Initiative (WPI Initiative), MEXT , Japan. M.Y. was supported by Leading Initiative for Excellent Young Researchers, MEXT , Japan.
Publisher Copyright:
© 2021 The Author(s)
PY - 2021/5/10
Y1 - 2021/5/10
N2 - 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.
AB - 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.
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U2 - 10.1016/j.physletb.2021.136238
DO - 10.1016/j.physletb.2021.136238
M3 - Article
AN - SCOPUS:85103096370
SN - 0370-2693
VL - 816
JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
M1 - 136238
ER -