5 papers
Riesz--Laurent representation of black-hole scattering and sourced response at exceptional points
Okuto Morikawa, Shoya Ogawa, Takuya Hirose
At a black-hole exceptional point (EP), two quasinormal modes coalesce and their separate residues become ill-conditioned. Rather than postulating a near-degenerate modal fit, we d…
Quasinormal modes and continuum response of de Sitter black holes via complex scaling method
Shoya Ogawa, Okuto Morikawa, Takuya Hirose
We apply the complex scaling method to black-hole perturbations in four-dimensional Schwarzschild--de~Sitter (dS) spacetimes. The method converts the outgoing-wave boundary-value p…
Complex scaling approach to quasinormal modes of Schwarzschild and Reissner--Nordström black holes
Shoya Ogawa, Takuya Hirose, Okuto Morikawa
We study black-hole quasinormal modes by applying the complex scaling method (CSM) to the perturbation equations of Schwarzschild and Reissner--Nordström black holes. The method co…
Cosmological Bounds on Scotogenic Model with Asymmetric Mediator
Kento Asai, Seishi Enomoto, Takuya Hirose +1
We study cosmological constraints on the asymmetric mediator scenario, a variant of the scotogenic model that addresses the origins of neutrino masses, dark matter (DM), and the ba…
Analysis of inflationary models in higher-dimensional uniform inflation
Takuya Hirose
We consider higher-dimensional uniform inflation, in which the extra dimensions expand at the same rate as three-dimensional non-compact space during inflation. We compute the cosm…