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Production of High Energy Neutrinos in the Coronae of Ultraluminous X-ray Sources
Norita Kawanaka, Shigeo S. Kimura
We investigate the possibility of high-energy neutrino production in coronae associated with ultraluminous X-ray sources (ULXs) as super-Eddington accreting black holes. Adopting t…
Diffusive or Ballistic? Distributions and Spectra of PeV Cosmic Rays around Microquasars
Yutaka Fujita, Rohta Takahashi, Norita Kawanaka
In the standard Galactic cosmic-ray (CR) paradigm, protons are accelerated up to ~1 PeV by Galactic sources. While supernova remnants (SNRs) have been traditionally considered as t…
Precision spectral measurements of Chromium and Titanium from 10 to 250 GeV and sub-Iron to Iron ratio with the Calorimetric Electron Telescope on the ISS
O. Adriani, Y. Akaike, K. Asano +77
The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray (CR) iron and sub-iron events over a…
Hadronic origin of the very high-energy gamma-ray emission from the low-luminosity AGN in NGC 4278
Asahi Shoji, Yutaka Fujita, Norita Kawanaka +2
The Large High Altitude Air Shower Observatory has detected very high-energy (VHE) gamma rays from NGC 4278, which is known to host a low-luminosity active galactic nucleus (AGN).…
ALMA observations of the gamma-ray binary system PSR B1259-63/LS 2883 during the 2024 periastron passage
Yutaka Fujita, Akiko Kawachi, Atsuo T. Okazaki +3
We present observations of the gamma-ray binary PSR B1259-63/LS 2883 with the Atacama Large Millimeter/submillimeter Array (ALMA) at Bands 3 (97 GHz), 6 (233 GHz), and 7 (343 GHz).…
Beyond Diffusion: A Causality-Preserving Model for Cosmic Ray Propagation
Norita Kawanaka, Rohta Takahashi
We propose a brand-new formalism for the propagation of relativistic cosmic ray (CR) particles. The propagation of CRs has often been described using the diffusion approximation, w…
A Relativistic Formula for the Multiple Scattering of Photons
Rohta Takahashi, Masayuki Umemura, Ken Ohsuga +6
We have discovered analytical expressions for the probability density function (PDF) of photons that are multiply scattered in relativistic flows, under the assumption of isotropic…
Direct Measurement of the Spectral Structure of Cosmic-Ray Electrons+Positrons in the TeV Region with CALET on the International Space Station
O. Adriani, Y. Akaike, K. Asano +77
Detailed measurements of the spectral structure of cosmic-ray electrons and positrons from 10.6 GeV to 7.5 TeV are presented from over 7 years of observations with the CALorimetric…
Broadband non-thermal emission of odd radio circles induced by explosive galactic outflow remnants and their evolution
Yutaka Fujita, Norita Kawanaka, Susumu Inoue
Odd radio circles (ORCs) are mysterious rings of faint, diffuse emission recently discovered in radio surveys, some of which may be associated with galaxies in relatively dense env…
The relationships between AGN power and molecular gas mass within 500 pc of the center of elliptical galaxies
Yutaka Fujita, Takuma Izumi, Hiroshi Nagai +2
The physical quantity that directly controls the feedback of active galactic nuclei (AGNs) in elliptical galaxies remains to be determined. The discovery of molecular gas around th…
Charge-Sign Dependent Cosmic-Ray Modulation Observed with the Calorimetric Electron Telescope on the International Space Station
O. Adriani, Y. Akaike, K. Asano +77
We present the observation of a charge-sign dependent solar modulation of galactic cosmic rays (GCRs) with the CALorimetric Electron Telescope onboard the International Space Stati…
Direct Measurement of the Cosmic-Ray Helium Spectrum from 40 GeV to 250 TeV with the Calorimetric Electron Telescope on the International Space Station
O. Adriani, Y. Akaike, K. Asano +77
We present the results of a direct measurement of the cosmic-ray helium spectrum with the CALET instrument in operation on the International Space Station since 2015. The observati…
Model of a `Warm Corona' as the Origin of the Soft X-ray Excess of Active Galactic Nuclei
Norita Kawanaka, Shin Mineshige
The soft X-ray excess in the spectra of active galactic nuclei is characterized by similar electron temperatures of 0.1 -- 0.3 keV and similar photon indices around 2.2 -- 3, if fi…
Cosmic-ray Boron Flux Measured from 8.4 GeV to 3.8 TeV with the Calorimetric Electron Telescope on the International Space Station
O. Adriani, Y. Akaike, K. Asano +77
We present the measurement of the energy dependence of the boron flux in cosmic rays and its ratio to the carbon flux \textcolor{black}{in an energy interval from 8.4 GeV to 3.…
Observation of Spectral Structures in the Flux of Cosmic-Ray Protons from 50 GeV to 60 TeV with the Calorimetric Electron Telescope on the International Space Station
O. Adriani, Y. Akaike, K. Asano +77
A precise measurement of the cosmic-ray proton spectrum with the Calorimetric Electron Telescope (CALET) is presented in the energy interval from 50 GeV to 60 TeV, and the observat…
CALET Search for electromagnetic counterparts of gravitational waves during the LIGO/Virgo O3 run
O. Adriani, Y. Akaike, K. Asano +78
The CALorimetric Electron Telescope (CALET) on the International Space Station (ISS) consists of a high-energy cosmic ray CALorimeter (CAL) and a lower-energy CALET Gamma ray Burst…
Direct Measurement of the Nickel Spectrum in Cosmic Rays in the Energy Range from 8.8 GeV/n to 240 GeV/n with CALET on the International Space Station
O. Adriani, Y. Akaike, K. Asano +78
The relative abundance of cosmic ray nickel nuclei with respect to iron is by far larger than for all other trans-iron elements, therefore it provides a favorable opportunity for a…
Detectablity of Black Hole Binaries with Gaia: Dependence on Binary Evolution Models
Minori Shikauchi, Ataru Tanikawa, Norita Kawanaka
Astrometric satellite Gaia is expected to observe non-interacting black hole (BH) binaries with luminous companions (LCs) (hereafter BH-LC binaries), a different population from BH…
Monte Carlo Study of Electron and Positron Cosmic-Ray Propagation with the CALET Spectrum
Katsuaki Asano, Yoichi Asaoka, Yosui Akaike +4
Focusing on the electron and positron spectrum measured with CALET, which shows characteristic structures, we calculate flux contributions of cosmic rays escaped from supernova rem…
Measurement of the Iron Spectrum in Cosmic Rays from 10 GeV to 2.0 TeV with the Calorimetric Electron Telescope on the International Space Station
O. Adriani, Y. Akaike, K. Asano +77
The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray iron over a wide energy interval. In…
Magnetically Arrested Disks in Quiescent Black-Hole Binaries: Formation Scenario, Observable Signatures, and Potential PeVatrons
Shigeo S. Kimura, Takahiro Sudoh, Kazumi Kashiyama +1
We propose magnetically arrested disks (MADs) in quiescent black-hole (BH) binaries as the origin of the multiwavelength emission, and argue that this class of sources can dominate…
Origin of Spectral Hardening of Secondary Cosmic-Ray Nuclei
Norita Kawanaka, Shiu-Hang Lee
We discuss the acceleration and escape of secondary cosmic-ray (CR) nuclei, such as lithium, beryllium and boron, produced by spallation of primary CR nuclei like carbon, nitrogen,…
Direct Measurement of the Cosmic-Ray Carbon and Oxygen Spectra from 10 GeV to 2.2 TeV with the Calorimetric Electron Telescope on the International Space Station
O. Adriani, Y. Akaike, K. Asano +81
In this paper, we present the measurement of the energy spectra of carbon and oxygen in cosmic rays based on observations with the Calorimetric Electron Telescope (CALET) on the In…
What Determines Unique Spectra of Super-Eddington Accretors?: Origin of Optically Thick and Low Temperature Coronae in Super-Eddington Accretion Flows
Norita Kawanaka, Shin Mineshige
Existence of relatively cool () and optically thick () coronae are inferred above super-Eddington accretion flow such as ultraluminous X-ra…