17 papers
Higher-Order Analytical Expansion of Thawing Dark Energy with an Exponential Potential
Naoto Maki, Kazunori Kohri
Motivated by recent DESI results suggesting dynamical dark energy, we investigate the thawing scenario in quintessence with an exponential potential, …
X-ray signals converted from high-frequency gravitational waves emitted by spinning light primordial black hole dark matter
Asuka Ito, Kazunori Kohri
We investigate the detectability of high-frequency gravitational waves from the superradiance of light primordial black hole dark matter through photons converted in the Galactic m…
A cross-calibration approach for polarisation-sensitive detectors in CMB experiments: application to LiteBIRD's polarisation angle calibration
A. Novelli, F. Piacentini, S. Micheli +102
One of the current challenges in observational cosmology is obtaining high-precision polarisation maps of the CMB to measure primordial -modes and constrain the tensor-to-scalar…
Graviton Floor
Himeka Matsuo, Asuka Ito, Kazunori Kohri +2
It has been observed that the Universe is permeated by the cosmic photon background, ranging from radio waves to gamma rays. We investigate the conversion of the photon background…
NANOGrav 15-year gravitational-wave signals from binary supermassive black-holes seeded by primordial black holes, and implications for the origins of Little Red Dots
Mikage U. Kobayashi, Kazunori Kohri
In this paper, we explain the recently reported a nHz-band gravitational-wave background from NANOGrav 15-year through the merger of binary super-massive black holes with masses of…
Natural Inflation with a negative cosmological constant
Chia-Min Lin, Naoto Maki, Kazunori Kohri
In this work, we investigate a cosmic inflation model based on a cosine-type potential with a negative cosmological constant. This model originates from a classical solution of the…