110 citations · 638 across the 27 of their papers we have counts for
27 papers
Monte Carlo simulations of relativistic shock breakout from a stellar wind
Hirotaka Ito, Amir Levinson, Ehud Nakar +1
We present Monte Carlo simulations of relativistic radiation-mediated shocks (RRMS) in the photon-starved regime, incorporating photon escape from the upstream region--characterize…
Numerical simulation of photospheric emission in long gamma-ray bursts: prompt correlations, spectral shapes, and polarizations
Hirotaka Ito, Jin Matsumoto, Shigehiro Nagataki +3
We explore the properties of photospheric emission in the context of long gamma-ray bursts (LGRBs) using three numerical models that combine relativistic hydrodynamical simulations…
GRB Prompt Emission: Observed Correlations and Their Interpretations
Tyler Parsotan, Hirotaka Ito
The prompt emission of Gamma Ray Bursts (GRBs) is still an outstanding question in the study of these cataclysmic events. Part of what makes GRBs difficult to study is how unique e…
A semi-analytic afterglow with thermal electrons and synchrotron self-Compton emission
Donald C. Warren, Maria Dainotti, Maxim V. Barkov +3
We extend previous work on gamma-ray burst (GRB) afterglows involving hot thermal electrons at the base of a shock-accelerated tail. Using a physically-motivated electron distribut…
A global numerical model of the prompt emission in short gamma-ray bursts
Hirotaka Ito, Oliver Just, Yuki Takei +1
We present the first global model of prompt emission from a short gamma-ray burst that consistently describes the evolution of the central black-hole (BH) torus system, the propaga…
Monte-Carlo simulations of fast Newtonian and mildly relativistic shock breakout from a stellar wind
Hirotaka Ito, Amir Levinson, Ehud Nakar
Strong explosion of a compact star surrounded by a thick stellar wind drives a fast () radiation mediated shock (RMS) that propagates in the wind, and ultimately breaks out…
Monte-Carlo simulations of relativistic radiation mediated shocks: II. photon starved regime
Hirotaka Ito, Amir Levinson, Shigehiro Nagataki
Radiation mediated shocks (RMS) play a key role in shaping the early emission observed in many transients. In most cases, e.g., shock breakout in supernovae, llGRBs and neutron sta…
The photospheric origin of the Yonetoku relation in gamma-ray bursts
Hirotaka Ito, Jin Matsumoto, Shigehiro Nagataki +3
Long duration gamma-ray bursts (GRBs), the brightest events since the Big Bang itself, are believed to originate in an ultra-relativistic jet breaking out from a massive stellar en…
Synchrotron self-absorption in GRB afterglows: the effects of a thermal electron population
Donald C. Warren, Maxim V. Barkov, Hirotaka Ito +2
In the standard synchrotron afterglow model, a power law of electrons is responsible for all aspects of photon production and absorption. Recent numerical work has shown that the v…
Monte-Carlo simulations of relativistic radiation mediated shocks: I. photon rich regime
Hirotaka Ito, Amir Levinson, Boris E. Stern +1
We explore the physics of relativistic radiation mediated shocks (RRMSs) in the regime where photon advection dominates over photon generation. For this purpose, a novel iterative…
Validation of Radiative Transfer Computation with Monte Carlo Method for Ultra-Relativistic Background Flow
Ayako Ishii, Naofumi Ohnishi, Hiroki Nagakura +2
We developed a three-dimensional radiative transfer code for an ultra-relativistic background flow-field by using the Monte Carlo (MC) method in the context of gamma-ray burst (GRB…
Fossil shell in 3C 84 as TeV -ray emitter and cosmic-ray accelerator
M. Kino, H. Ito, K. Wajima +3
We explore physical properties of the shocked external medium (i.e., a shell) in 3C 84 associated with the recurrent radio lobe born around 1960. In the previous work of Ito et al.…
The young radio lobe of 3C 84: inferred gas properties in the central 10 parsec
Yutaka Fujita, Nozomu Kawakatu, Isaac Shlosman +1
We analyse the environment of the supermassive black hole (SMBH) in the centre of a massive elliptical galaxy NGC 1275 in the Perseus cluster, hosting the radio source 3C 84. We fo…
Photospheric Emission from Collapsar Jets in 3D Relativistic Hydrodynamics
Hirotaka Ito, Jin Matsumoto, Shigehiro Nagataki +2
We explore the photospheric emission from a relativistic jet breaking out from a massive stellar envelope based on relativistic hydrodynamical simulations and post-process radiatio…
Fossil shell emission in dying radio loud AGNs
M. Kino, H. Ito, N. Kawakatu +4
We investigate shell emission associated with dying radio loud AGNs. First, based on our recent work by Ito et al. (2015), we describe the dynamical and spectral evolutions of shel…
Matter Mixing in Core-collapse Supernova Ejecta: Large Density Perturbations in the Progenitor Star?
J. Mao, M. Ono, S. Nagataki +5
Matter mixing is one important topic in the study of core-collapse supernova (CCSN) explosions. In this paper, we perform two-dimensional hydrodynamic simulations to reproduce the…
Particle acceleration in superluminal strong waves
Yuto Teraki, Hirotaka Ito, Shigehiro Nagataki
We calculate the electron acceleration in random superluminal strong waves (SLSWs) and radiation from them by using numerical methods in the context of the termination shock of the…
The Fate of Dead Radio-loud Active Galactic Nuclei: A New Prediction of Long-lived Shell Emission
Hirotaka Ito, Motoki Kino, Nozomu Kawakatu +1
We examine the fate of a dead radio source in which jet injection from the central engine has stopped at an early stage of its evolution ( yr). To this aim,…
Spectral and Polarization Properties of Photospheric Emission From Stratified Jets
Hirotaka Ito, Shigehiro Nagataki, Jin Matsumoto +5
We explore the spectral and polarization properties of photospheric emissions from stratified jets in which multiple components, separated by a sharp velocity shear regions, are di…
Matter mixing in aspherical core-collapse supernovae: a search for possible conditions for conveying Ni into high velocity regions
Masaomi Ono, Shigehiro Nagataki, Hirotaka Ito +4
We perform two-dimensional axisymmetric hydrodynamic simulations of matter mixing in aspherical core-collapse supernova explosions of a 16.3 star with a compact hydroge…
Photospheric emission from stratified jets
Hirotaka Ito, Shigehiro Nagataki, Masaomi Ono +6
We explore photospheric emissions from stratified two-component jets, wherein a highly relativistic spine outflow is surrounded by a wider and less relativistic sheath outflow. The…
New class of Very High Energy gamma-ray emitter: radio-dark mini-shells surrounding AGN jets
Motoki Kino, Hirotaka Ito, Nozomu Kawakatu +1
We explore non-thermal emission from a shocked interstellar medium, which is identified as an expanding shell, driven by a relativistic jet in active galactic nuclei (AGNs). In thi…
Jet propagations, breakouts and photospheric emissions in collapsing massive progenitors of long duration gamma ray bursts
Hiroki Nagakura, Hirotaka Ito, Kenta Kiuchi +1
We investigate by two-dimensional axisymmetric relativistic hydrodynamical simulations (1) jet propagations through an envelope of a rapidly rotating and collapsing massive star, w…
Non-Thermal emissions from shocked shells driven by powerful AGN jets
H. Ito, M. Kino, N. Kawakatu +1
We explore the emissions by accelerated electrons in shocked shells driven by jets in active galactic nuclei (AGNs). Focusing on powerful sources which host luminous quasars, the s…