7 papers
Lattice study of primordial black hole formation in bumpy axion inflation
Masahiro Kawasaki, Kai Murai, Shunsuke Tsuchida
We study primordial black hole (PBH) formation in axion inflation using lattice simulations. In axion inflation with a bumpy potential, the curvature perturbations ca…
Merger rate of initially clustered primordial black holes for the two-body channel
Kentaro Kasai, Masahiro Kawasaki, Kai Murai +1
Primordial black holes (PBHs) may form an initially clustered population depending on their production mechanism. Motivated by binary black-hole merger events observed by gravitati…
EMPRESS. XV. A New Determination of the Primordial Helium Abundance Suggesting a Moderately Low Value
Hiroto Yanagisawa, Masami Ouchi, Akinori Matsumoto +18
We present a new constraint on the primordial helium abundance, , based on Subaru observations. A major source of uncertainty in previous determination…
Microlensing events and primordial black holes in the axionlike curvaton model
Kentaro Kasai, Masahiro Kawasaki, Kai Murai +1
Recently, Subaru Hyper Suprime-Cam (HSC) observations found 12 candidates for microlensing events. These events can be explained by primordial black holes (PBHs) with masses of $10…
Resonant production of sterile neutrino dark matter with a refined numerical scheme
Kentaro Kasai, Masahiro Kawasaki, Kai Murai
The existence of a large primordial neutrino asymmetry is an intriguing possibility, both observationally and theoretically. Such an asymmetry can lead to the resonant production o…
Clustering of Primordial Black Holes from QCD Axion Bubbles
Kentaro Kasai, Masahiro Kawasaki, Naoya Kitajima +3
We study the clustering of primordial black holes (PBHs) and axion miniclusters produced in the model proposed to explain the LIGO/Virgo events or the seeds of the supermassive bla…