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Origin of the complex iron line structure and spectral variation in Mrk 766
Yuto Mochizuki, Misaki Mizumoto, Ken Ebisawa
Complex Fe-K emission/absorption line features are commonly observed in the 6--11 keV band from Active Galactic Nuclei (AGN). These features are formed in various physical componen…
Radiatively-driven clumpy X-ray absorbers in the NLS1 galaxy IRAS 13224-3809
Takuya Midooka, Misaki Mizumoto, Ken Ebisawa
Recent radiation-magnetohydrodynamic simulations of active galactic nuclei predict the presence of the disk winds, which may get unstable and turn into fragmented clumps far from t…
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…
X-ray time lag evaluation of MAXI J1820+070 with a differential cross-correlation analysis
Tomoki Omama, Masahiro Tsujimoto, Ken Ebisawa +1
MAXI J1820070 is a transient black hole binary (BHB) discovered on 2018 March 11. The unprecedented rich statistics brought by the NICER X-ray telescope allows detailed timing a…
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.…
A novel "spectral-ratio model fitting" to resolve complicated AGN X-ray spectral variations
Takuya Midooka, Misaki Mizumoto, Ken Ebisawa
Contemporary radiation-magnetohydrodynamic simulation of the AGNs predicts presence of the hot and strong accretion disk wind, which gets unstable far from the central region and t…
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…
Simple interpretation of the seemingly complicated X-ray spectral variation of NGC 5548
Takuya Midooka, Ken Ebisawa, Misaki Mizumoto +1
NGC 5548 is a very well-studied Seyfert 1 galaxy in broad wavelengths. Previous multiwavelength observation campaigns have indicated that its multiple absorbers are highly variable…
Long Term X-Ray Spectral Variation of the Wolf-Rayet Binary WR 102-1 in the Galactic bulge: evidence for wind distortion in the binary
Tomoki Nagatsuka, Yasuharu Sugawara, Ken Ebisawa
WR~102-1 was detected by Suzaku as a conspicuous point source in the 6.7 keV intensity map of the central region of the Milky Way. The source was suggested as a possible Wolf-Rayet…
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…
Deep Near-infrared Imaging Observation of the Faint X-ray Point Sources Constituting the Galactic Bulge X-ray Emission
Kumiko Morihana, Masahiro Tsujimoto, Ken Ebisawa +1
Presence of the apparently extended hard (2-10 keV) X-ray emission along the Galactic plane has been known since the early 1980s. With a deep X-ray exposure using the Chandra X-ray…
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…
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…
Discovery of the black hole X-ray binary transient MAXIJ1348-630
Mayu Tominaga, Satoshi Nakahira, Megumi Shidatsu +8
We report the first half-year monitoring of the new Galactic black hole candidate MAXI J1348-630, discovered on 2019 January 26 with the Gas Slit Camera (GSC) on-board MAXI. During…
Long-term X-ray variation of the colliding wind Wolf-Rayet binary WR 125
Takuya Midooka, Yasuharu Sugawara, Ken Ebisawa
WR 125 is considered as a Colliding Wind Wolf-rayet Binary (CWWB), from which the most recent infrared flux increase was reported between 1990 and 1993. We observed the object four…
Detection of polarized gamma-ray emission from the Crab nebula with Hitomi Soft Gamma-ray Detector
Hitomi Collaboration, Felix Aharonian, Hiroki Akamatsu +191
We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrom…
X-ray reverberation lags of the Fe-K line due to AGN disc winds
Misaki Mizumoto, Ken Ebisawa, Masahiro Tsujimoto +3
Short X-ray reverberation lags are seen across a broad Fe-K energy band in more than twenty active galactic nuclei (AGNs). This broad iron line feature in the lag spectrum is most…
Search for GeV Gamma-ray Counterparts of Gravitational Wave Events by CALET
O. Adriani, Y. Akaike, K. Asano +88
We present results on searches for gamma-ray counterparts of the LIGO/Virgo gravitational-wave events using CALorimetric Electron Telescope ({\sl CALET}) observations. The main ins…
Extended Measurement of the Cosmic-Ray Electron and Positron Spectrum from 11 GeV to 4.8 TeV with the Calorimetric Electron Telescope on the International Space Station
O. Adriani, Y. Akaike, K. Asano +88
Extended results on the cosmic-ray electron + positron spectrum from 11 GeV to 4.8 TeV are presented based on observations with the Calorimetric Electron Telescope (CALET) on the I…
X-ray short-time lags in the Fe-K energy band produced by scattering clouds in active galactic nuclei
Misaki Mizumoto, Chris Done, Kouichi Hagino +3
X-rays illuminating the accretion disc in active galactic nuclei give rise to an iron K line and its associated reflection spectrum which are lagged behind the continuum variabilit…
Can the relativistic light bending model explain X-ray spectral variations of Seyfert galaxies?
Misaki Mizumoto, Kotaro Moriyama, Ken Ebisawa +3
Many Seyfert galaxies are known to exhibit Fe-K broad emission line features in their X-ray energy spectra. The observed lines have three distinct features; (1) the line profiles a…
Hitomi X-ray Observation of the Pulsar Wind Nebula G21.50.9
Hitomi Collaboration, Felix Aharonian, Hiroki Akamatsu +194
We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.50.9, whose emission is dominated by the pulsar wind nebula (PWN) cont…
Energy Dependent Intensity Variation of the Persistent X-ray Emission of Magnetars Observed with Suzaku
Yujin Nakagawa, Ken Ebisawa, Teruaki Enoto
Emission mechanism of the magnetars is still controversial while various observational and theoretical studies have been made. In order to investigate mechanisms of both the persis…