4 papers
Imprints of Dark Photons on Gravitational Wave Polarizations
Kimihiro Nomura, Jiro Soda, Kazushige Ueda +1
We study conversion processes between gravitons and dark photons and reveal the effects of dark photons on the polarization of gravitational waves. Considering cosmological dark ma…
Past extendibility and initial singularity in Friedmann-Lemaître-Robertson-Walker and Bianchi I spacetimes
Kimihiro Nomura, Daisuke Yoshida
We study past-directed extendibility of Friedmann-Lemaître-Robertson-Walker (FLRW) and Bianchi type I spacetimes with a scale factor vanishing in the past. We give criteria for det…
Stability of magnetic black holes in general nonlinear electrodynamics
Kimihiro Nomura, Daisuke Yoshida, Jiro Soda
We study the perturbative stability of magnetic black holes in a general class of nonlinear electrodynamics, where the Lagrangian is given by a general function of the field streng…
Pulsar timing residual induced by ultralight vector dark matter
Kimihiro Nomura, Asuka Ito, Jiro Soda
We study the ultralight vector dark matter with a mass around . The vector field oscillating coherently on galactic scales induces oscillations of the spacet…