902 citations · 3.2k across the 78 of their papers we have counts for
80 papers
Revisiting damping of Alfvén waves in partially ionized plasmas
Yutaka Ohira
We investigate the damping rate of Alfvén waves by means of the linear analysis of the two-fluid ten-moments system. To treat effects of viscosity in a wide frequency range, we tak…
Cosmic-ray Acceleration in Core-Collapse Supernova Remnants with the Wind Termination Shock
Shoma F. Kamijima, Yutaka Ohira
We investigate the attainable maximum energy of particles accelerated in the core-collapse supernova remnant (SNR) shock propagating in the free wind region with the Parker-spiral…
Resistive Heating Induced by Streaming Cosmic Rays Around a Galaxy in the Early Universe
Shota L. Yokoyama, Yutaka Ohira
It is expected that cosmic rays (CRs) escape from high-redshift galaxies at redshift because CRs are accelerated by supernova remnants of the first stars. Alt…
Two-component jet model for multiwavelength afterglow emission of the extremely energetic burst GRB 221009A
Yuri Sato, Kohta Murase, Yutaka Ohira +1
Recently gamma-ray bursts (GRBs) have been detected at very high-energy (VHE) gamma-rays by imaging atmospheric Cherenkov telescopes, and a two-component jet model has often been i…
Synchrotron Self-Compton Emission in the Two-Component Jet Model for Gamma-Ray Bursts
Yuri Sato, Kaori Obayashi, B. Theodre Zhang +4
Gamma-ray bursts (GRBs) are intense bursts of high-energy photons (prompt emissions) caused by relativistic jets. After the emissions, multi-wavelength afterglows, from radio to ve…
Probing particle acceleration at trans-relativistic shocks with off-axis gamma-ray burst afterglows
Kazuya Takahashi, Kunihito Ioka, Yutaka Ohira +1
Particle acceleration is expected to be different between relativistic and non-relativistic collisionless shocks. We show that electromagnetic counterparts to gravitational waves (…
Escape of cosmic rays from perpendicular shocks in the circumstellar magnetic field
Shoma F. Kamijima, Yutaka Ohira
We investigate the escape process of cosmic rays (CRs) from perpendicular shock regions of a spherical shock propagating to a circumstellar medium with the Parker-spiral magnetic f…
The Gamma-Ray Emission from the Supernova Remnant RX J1713.7-3946 Interacting with Two-phase Medium
Yutaka Fujita, Ryo Yamazaki, Yutaka Ohira
We study the origin of gamma rays from the supernova remnant (SNR) RX J1713.7-3946. Using an analytical model, we calculate the distribution of cosmic rays (CRs) around the SNRs. M…
Interaction of a Relativistic Magnetized Collisionless Shock with a Dense Clump
Sara Tomita, Yutaka Ohira, Shigeo S. Kimura +2
The interactions between a relativistic magnetized collisionless shock and dense clumps have been expected to play a crucial role on the magnetic field amplification and cosmic-ray…
Biermann Battery Powered by Resistive Heating Induced by Cosmic Ray Streaming
Shota L. Yokoyama, Yutaka Ohira
It is recently proposed that cosmic rays generate a seed magnetic field in the early universe. In this paper, we propose another generation mechanism of magnetic fields by cosmic r…
X-ray Line Diagnostics of Ion Temperature at Cosmic-Ray Accelerating Collisionless Shocks
Jiro Shimoda, Yutaka Ohira, Aya Bamba +4
A novel collisionless shock jump condition is suggested by modeling the entropy production at the shock transition region. We also calculate downstream developments of the atomic i…
Self-discharge by streaming cosmic rays
Yutaka Ohira
A new nonthermal phenomenon caused by streaming cosmic rays (CRs) in the universe is proposed. The streaming CRs drive the return current of thermal electrons to compensate for the…
Observational constraints on the maximum energies of accelerated particles in supernova remnants: low maximum energies and a large variety
Hiromasa Suzuki, Aya Bamba, Ryo Yamazaki +1
Supernova remnants (SNRs) are thought to be the most promising sources of Galactic cosmic rays. One of the principal questions is whether they are accelerating particles up to the…
Identification of electrostatic two-stream instabilities associated with a laser-driven collisionless shock in a multicomponent plasma
Youichi Sakawa, Yutaka Ohira, Rajesh Kumar +3
Electrostatic two-stream instabilities play essential roles in an electrostatic collisionless shock formation. They are a key dissipation mechanism and result in ion heating and ac…
Escape of cosmic rays from perpendicular shocks in the interstellar magnetic field
Shoma F. Kamijima, Yutaka Ohira
We investigate the escape process from a perpendicular shock region of a spherical shock in the interstellar medium (ISM). The diffusive shock acceleration in the perpendicular sho…
Magnetic field generation by charge exchange in a supernova remnant in the early universe
Shuhei Kashiwamura, Yutaka Ohira
We present new generation mechanisms of magnetic fields in supernova remnant shocks propagating to partially ionized plasmas in the early universe. Upstream plasmas are dissipated…
The Biermann battery driven by a streaming plasma
Yutaka Ohira
The Biermann battery is a promising generation mechanism of a seed magnetic field in the universe. We propose a new driving mechanism for the Biermann battery in an inhomogeneous p…
Off-axis jet scenario for early afterglow emission of low-luminosity gamma-ray burst GRB 190829A
Yuri Sato, Kaori Obayashi, Ryo Yamazaki +2
Recently, ground-based Imaging Atmospheric Cherenkov Telescopes have reported the detection of very-high-energy (VHE) gamma-rays from some gamma-ray bursts (GRBs). One of them, GRB…
Sensitivity of the Cherenkov Telescope Array for probing cosmology and fundamental physics with gamma-ray propagation
The Cherenkov Telescope Array Consortium, :, H. Abdalla +496
The Cherenkov Telescope Array (CTA), the new-generation ground-based observatory for -ray astronomy, provides unique capabilities to address significant open questions in astrop…
Sensitivity of the Cherenkov Telescope Array to a dark matter signal from the Galactic centre
The Cherenkov Telescope Array Consortium, :, A. Acharyya +449
We provide an updated assessment of the power of the Cherenkov Telescope Array (CTA) to search for thermally produced dark matter at the TeV scale, via the associated gamma-ray sig…
Study on the escape timescale of high-energy particles from supernova remnants through thermal X-ray properties
Hiromasa Suzuki, Aya Bamba, Ryo Yamazaki +1
In this decade, GeV/TeV gamma-ray observations of several supernova remnants (SNRs) have implied that accelerated particles are escaping from their acceleration sites. However, whe…
Magnetic field generation by an inhomogeneous return current
Yutaka Ohira
A new generation mechanism of the magnetic field in an inhomogeneous collisionless plasma with a beam component is proposed. We show that even though the current and charge neutral…
Fast Particle Acceleration at Perpendicular Shocks with Uniform Upstream Magnetic Field and Strong Downstream Turbulence
Shoma F. Kamijima, Yutaka Ohira, Ryo Yamazaki
The shock waves produce relativistic particles via the diffusive shock acceleration (DSA) mechanism. Among various circumstances, fast acceleration has been expected for perpendicu…
Particle acceleration in a shock wave propagating to an inhomogeneous medium
Shota L. Yokoyama, Yutaka Ohira
We investigate effects of upstream density fluctuations on the diffusive shock acceleration by Monte Carlo simulations. The simulations show that particles are reaccelerated in the…