Constraint on ghost-free bigravity from gravitational Cherenkov radiation

Rampei Kimura, Takahiro Tanaka, Kazuhiro Yamamoto, and Yasuho Yamashita
Phys. Rev. D 94, 064059 – Published 21 September 2016

Abstract

We investigate gravitational Cherenkov radiation in a healthy branch of background solutions in the ghost-free bigravity model. In this model, because of the modification of dispersion relations, each polarization mode can possess subluminal phase velocities, and the gravitational Cherenkov radiation could be potentially emitted from a relativistic particle. In the present paper, we derive conditions for the process of the gravitational Cherenkov radiation to occur and estimate the energy emission rate for each polarization mode. We found that the gravitational Cherenkov radiation emitted even from an ultrahigh energy cosmic ray is sufficiently suppressed for the graviton’s effective mass less than 100 eV, and the bigravity model with dark matter coupled to the hidden metric is therefore consistent with observations of high energy cosmic rays.

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  • Received 18 May 2016

DOI:https://doi.org/10.1103/PhysRevD.94.064059

© 2016 American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & Astrophysics

Authors & Affiliations

Rampei Kimura1, Takahiro Tanaka2,3, Kazuhiro Yamamoto4, and Yasuho Yamashita3

  • 1Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
  • 2Department of Physics, Kyoto University, 606-8502 Kyoto, Japan
  • 3Yukawa Institute for Theoretical Physics, Kyoto University, 606-8502 Kyoto, Japan
  • 4Department of Physical Sciences, Hiroshima University, Kagamiyama 1-3-1, Higashi-hiroshima 739-8526, Japan

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Issue

Vol. 94, Iss. 6 — 15 September 2016

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