256 citations · 2.5k across the 78 of their papers we have counts for
79 papers
Constraining the FRB Central Engine from Flux Variations of Persistent Radio Sources: FRB 20240114A as the First Attempt
Hirotaka Matsumiya, Kazumi Kashiyama, Tomonori Totani
Some repeating fast radio bursts (FRBs) are associated with persistent radio sources (PRSs), likely driven by the long-term activity of a central engine. We investigate FRB 2024011…
A Diagnostic Method for Proto-Neutron Star Magnetic Fields by Supernova Fallback Neutrinos
Akihiro Inoue, Yudai Suwa, Ryuichiro Akaho +3
Young isolated neutron stars exhibit a wide range of magnetic field strengths. To understand the origin of this diversity, it is important to observationally constrain magnetic fie…
The Ultrafast Line-Driven Wind from the Double-Degenerate Merger Remnant WD J005311
Kazuma Kato, Kazumi Kashiyama
We systematically construct steady-state wind solutions for double-degenerate merger remnants consisting of a degenerate oxygen-neon core and an optically thick expanding envelope…
A Type Ia Supernova Candidate at : A Transient Interloper in the Search for Galaxies
Seiji Toshikage, Takahiro Morishita, Masaomi Tanaka +9
The James Webb Space Telescope (JWST) is opening a new window into the distant Universe by discovering galaxies and transients in the early Universe. We investigate a high-redshift…
Blowouts of Nascent Wind Bubbles in Pulsar-Driven Supernovae
Mingxi Chen, Kazumi Kashiyama, Masato Sato
Formation of a rapidly spinning, strongly magnetized neutron star (NS) may occur in various classes of core-collapse events. If the NS injects an amount of energy comparable to the…
Super-knee cosmic rays from interacting supernovae
Nick Ekanger, Shigeo S. Kimura, Kazumi Kashiyama
There is increasing evidence that, in the very late phase of stellar evolution before core collapse, massive stars have winds with large mass loss rates that give rise to a dense c…
Successive Partial Disruptions with Orbital Precession in a White Dwarf-Black Hole System for Repeating GRB 250702B
Yuri Sato, Rin Oikawa, Kazuma Kato +2
The peculiar gamma-ray burst GRB 250702B is the longest event ever observed, lasting about one day and exhibiting four prompt-emission flares of s with irregular recurren…
Relaxation of time-variable neutron-loaded relativistic jets across the photosphere and their GeV-TeV neutrino counterparts
Kanako Nakama, Kazumi Kashiyama, Nobuhiro Shimizu
Both observational and theoretical studies indicate that the central engine of a gamma-ray burst (GRB) is intrinsically time-variable, implying jet inhomogeneity. A jet with an inh…
Spectral Uniformity of Little Red Dots: A Natural Outcome of Coevolving Seed Black Holes and Nascent Starbursts
Kohei Inayoshi, Kohta Murase, Kazumi Kashiyama
The birth of seeds of massive black holes (BHs) and nascent galaxies at cosmic dawn takes place in dense gaseous environments, which play a crucial role in shaping their coevolutio…
A Necessary Condition for the Submergence of Proto-Neutron Star Magnetic Fields by Supernova Fallback
Akihiro Inoue, Shinsuke Takasao, Kazumi Kashiyama +2
Central compact objects (CCOs) are a subclass of neutron stars with a dipole magnetic field strength considerably weaker than those of radio pulsars and magnetars. One possible exp…
EP240414a: A Gamma-Ray Burst Jet Weakened by an Extended Circumstellar Material
Hamid Hamidani, Yuri Sato, Kazumi Kashiyama +3
The recent Einstein Probe (EP) event EP240414a exhibits several unusual observational features. Its prompt and afterglow emissions place it between long gamma-ray bursts (LGRBs) an…
Gamma-Ray Burst Jets in Circumstellar Material: Dynamics, Breakout, and Diversity of Transients
Hamid Hamidani, Kunihito Ioka, Kazumi Kashiyama +1
Recent observations indicate that stripped-envelope core-collapse supernovae are often surrounded by dense circumstellar material (CSM). Motivated by this, we develop an analytic m…
Quasi-steady emission from repeating fast radio bursts can be explained by magnetar wind nebulae
Mukul Bhattacharya, Kohta Murase, Kazumi Kashiyama
Among more than 1000 known fast radio bursts (FRBs), only five sources - FRBs 20121102A, 20190520B, 20201124A, 20240114A and 20190417A - have confirmed associations with persistent…
On the X-ray efficiency of the white dwarf pulsar candidate ZTF J190132.9+145808.7
Aya Bamba, Yukikatsu Terada, Kazumi Kashiyama +3
Strongly magnetized, rapidly rotating massive white dwarfs (WDs) emerge as potential outcomes of double degenerate mergers. These WDs can act as sources of non-thermal emission and…
Exploring faint white dwarfs and the luminosity function with Subaru HSC and SDSS in Stripe 82
Tian Qiu, Masahiro Takada, Naoki Yasuda +4
We present 5,080 white dwarf (WD) candidates selected from stars matching between the multi-band imaging datasets of the Subaru Hyper Suprime-Cam (HSC) Survey and the Sloan Digital…
Exploring Low-Mass Black Holes through Tidal Disruption Events in the Early Universe: Perspectives in the Era of JWST, RST, and LSST Surveys
Kohei Inayoshi, Kazumi Kashiyama, Wenxiu Li +3
The James Webb Space Telescope (JWST) has recently uncovered the presence of low-luminosity active galactic nuclei (AGNs) at . Spectroscopic observations have provided esti…
The optically thick rotating magnetic wind from a massive white dwarf merger product -- II. axisymmetric magnetohydrodynamic simulations
Yici Zhong, Kazumi Kashiyama, Shinsuke Takasao +2
We numerically construct a series of axisymmetric rotating magnetic wind solutions, aiming at exploring the observation properties of massive white dwarf (WD) merger remnants with…
Testing a stochastic acceleration model of pulsar wind nebulae: Early evolution of a wind nebula associated with SN 1986J
Shuta J. Tanaka, Kazumi Kashiyama
Over three thousand pulsars have been discovered, but none have been confirmed to be younger than a few hundred years. Observing a pulsar after a supernova explosion will help us u…
Gravitational Collapse of White Dwarfs to Neutron Stars. I. From Initial Conditions to Explosions with Neutrino-radiation Hydrodynamics Simulations
Masamitsu Mori, Ryo Sawada, Yudai Suwa +3
This paper provides collapses of massive, fully convective, and non-rotating white dwarfs (WDs) formed by accretion-induced collapse or merger-induced collapse and the subsequent e…
MASTER OT J030227.28+191754.5: a dwarf nova at a massive oxygen-neon white-dwarf system ?
Mariko Kimura, Kazumi Kashiyama, Toshikazu Shigeyama +3
We present timing and spectral analysis results of the {\it NICER} and {\it NuSTAR} observations of the dwarf nova MASTER OT J030227.28191754.5 during the 2021--2022 outburst. T…
A dynamical model for IRAS 00500+6713: the remnant of a type Iax supernova SN 1181 hosting a double degenerate merger product WD J005311
Takatoshi Ko, Hiromasa Suzuki, Kazumi Kashiyama +6
IRAS 00500+6713 is a hypothesized remnant of a type Iax supernova SN 1181. Multi-wavelength observations have revealed its complicated morphology; a dusty infrared ring is sandwich…
Modeling photometric variations due to a global inhomogeneity on an obliquely rotating star: application to lightcurves of white dwarfs
Yasushi Suto, Shin Sasaki, Masataka Aizawa +2
We develop a general framework to compute photometric variations induced by the oblique rotation of a star with an axisymmetric inhomogeneous surface. We apply the framework to com…
Fast optical flares from M dwarfs detected by a one-second-cadence survey with Tomo-e Gozen
Masataka Aizawa, Kojiro Kawana, Kazumi Kashiyama +18
We report a one-second-cadence wide-field survey for M-dwarf flares using the Tomo-e Gozen camera mounted on the Kiso Schmidt telescope. We detect 22 flares from M3-M5 dwarfs with…
X-raying the Birth of Binary Neutron Stars and Neutron Star-Black Hole Binaries
Kazumi Kashiyama, Ryo Sawada, Yudai Suwa
We consider fallback accretion after an ultra-stripped supernova (USSN) that accompanies formation of a binary neutron star (BNS) or a neutron star-black hole binary (NS-BH). The f…