242 citations · 2.3k across the 31 of their papers we have counts for
31 papers
Axion Curvaton Model for the Gravitational Waves Observed by Pulsar Timing Arrays
Keisuke Inomata, Masahiro Kawasaki, Kyohei Mukaida +1
The stochastic gravitational wave background (SGWB) recently detected by the PTA collaborations could be the gravitational waves (GWs) induced by curvature perturbations. However,…
The Detected Stochastic Gravitational Waves and Subsolar-Mass Primordial Black Holes
Keisuke Inomata, Kazunori Kohri, Takahiro Terada
Multiple pulsar timing array (PTA) collaborations recently announced the evidence of common-spectral processes caused by gravitational waves (GWs). These can be the stochastic GW b…
Axion Poltergeist
Keisuke Harigaya, Keisuke Inomata, Takahiro Terada
Rotations of axion fields in the early universe can produce dark matter and the matter-antimatter asymmetry of the universe. We point out that the rotation can generate an observab…
Synchronizing the Consistency Relation
Keisuke Inomata, Hayden Lee, Wayne Hu
We study the -point function of the density contrast to quadratic order in the squeezed limit during the matter-dominated (MD) and radiation-dominated (RD) eras in synchronous g…
Questions on calculation of primordial power spectrum with large spikes: the resonance model case
Keisuke Inomata, Matteo Braglia, Xingang Chen +1
Inflationary models predicting a scale-dependent large amplification of the density perturbations have recently attracted a lot of attention because the amplified perturbations can…
Snowmass2021 Cosmic Frontier White Paper:Primordial Black Hole Dark Matter
Simeon Bird, Andrea Albert, Will Dawson +13
Primordial Black Holes (PBHs) are a viable candidate to comprise some or all of the dark matter and provide a unique window into the high-energy physics of the early universe. This…
Traces of a Heavy Field in Gravitational Waves
Keisuke Inomata
We discuss gravitational waves (GWs) induced by a heavy spectator field that starts to oscillate during inflation. During the oscillation of the spectator field, its effective mass…
Spectral Distortion Anisotropy from Inflation for Primordial Black Holes
David Zegeye, Keisuke Inomata, Wayne Hu
Single field inflationary models that seek to greatly enhance small scale power in order to form primordial black holes predict both a squeezed bispectrum that is enhanced by this…
Amplification of Primordial Perturbations from the Rise or Fall of the Inflaton
Keisuke Inomata, Evan McDonough, Wayne Hu
The next generation of cosmic microwave background, gravitational wave, and large scale structure, experiments will provide an unprecedented opportunity to probe the primordial pow…
Bound on Induced Gravitational Waves during Inflation Era
Keisuke Inomata
We put the upper bound on the gravitational waves (GWs) induced by the scalar-field fluctuations during the inflation. In particular, we focus on the case where the scalar fluctuat…
Primordial Black Holes Arise When The Inflaton Falls
Keisuke Inomata, Evan McDonough, Wayne Hu
Primordial Black Holes (PBHs) have entered the forefront of theoretical cosmology, due their potential role in phenomena ranging from gravitational waves, to dark matter, to galaxy…
NANOGrav results and LIGO-Virgo primordial black holes in axion-like curvaton model
Keisuke Inomata, Masahiro Kawasaki, Kyohei Mukaida +1
We discuss a possible connection between the recent NANOGrav results and the primordial black holes (PBHs) for the LIGO-Virgo events. In particular, we focus on the axion-like curv…
Analytic solutions of scalar perturbations induced by scalar perturbations
Keisuke Inomata
We study scalar perturbations induced by scalar perturbations through the non-linear interaction appearing at second order in perturbations. We derive analytic solutions of the ind…
Standard Model Prediction for Cosmological 21cm Circular Polarization
Lingyuan Ji, Marc Kamionkowski, Keisuke Inomata
Before cosmic reionization, hydrogen atoms acquire a spin polarization quadrupole through interaction with the anisotropic 21-cm radiation field. The interaction of this quadrupole…
Window function dependence of the novel mass function of primordial black holes
Koki Tokeshi, Keisuke Inomata, Jun'ichi Yokoyama
We investigate the ambiguity of the novel mass function of primordial black holes, which has succeeded in identifying the black hole mass in a given configuration of fluctuations,…
Gravitational Wave Production right after a Primordial Black Hole Evaporation
Keisuke Inomata, Masahiro Kawasaki, Kyohei Mukaida +2
We discuss the footprint of evaporation of primordial black holes (PBHs) on stochastic gravitational waves (GWs) induced by scalar perturbations. We consider the case where PBHs on…
Gauge Independence of Induced Gravitational Waves
Keisuke Inomata, Takahiro Terada
We study gauge (in)dependence of the gravitational waves (GWs) induced from curvature perturbations. For the GWs produced in a radiation-dominated era, we find that the observable…
Enhancement of Gravitational Waves Induced by Scalar Perturbations due to a Sudden Transition from an Early Matter Era to the Radiation Era
Keisuke Inomata, Kazunori Kohri, Tomohiro Nakama +1
We study gravitational waves induced from the primordial scalar perturbations at second order around the reheating of the Universe. We consider reheating scenarios in which a trans…
Gravitational Waves Induced by Scalar Perturbations during a Gradual Transition from an Early Matter Era to the Radiation Era
Keisuke Inomata, Kazunori Kohri, Tomohiro Nakama +1
We revisit the effects of an early matter-dominated era on gravitational waves induced by scalar perturbations. We carefully take into account the evolution of the gravitational po…
Gravitational waves induced by scalar perturbations as probes of the small-scale primordial spectrum
Keisuke Inomata, Tomohiro Nakama
Compared to primordial perturbations on large scales, roughly larger than megaparsec, those on smaller scales are not severely constrained. We revisit the issue of probing smal…
Chiral photons from chiral gravitational waves
Keisuke Inomata, Marc Kamionkowski
We show that a parity-breaking uniform (averaged over all directions on the sky) circular polarization of amplitude can be induced…
Circular polarization of the cosmic microwave background from vector and tensor perturbations
Keisuke Inomata, Marc Kamionkowski
Circular polarization of the cosmic microwave background (CMB) can be induced by Faraday conversion of the primordial linearly polarized radiation as it propagates through a birefr…
Big Bang Nucleosynthesis Constraint on Baryonic Isocurvature Perturbations
Keisuke Inomata, Masahiro Kawasaki, Alexander Kusenko +1
We study the effect of large baryonic isocurvature perturbations on the abundance of deuterium (D) synthesized in big bang nucleosynthesis (BBN). We found that large baryonic isocu…
Exploring compensated isocurvature perturbations with CMB spectral distortion anisotropies
Taku Haga, Keisuke Inomata, Atsuhisa Ota +1
We develop a linear perturbation theory for the spectral -distortions of the cosmic microwave background (CMB). The -distortions generated during the recombination epoch are…