Masahiro Tsujimoto Misaki Mizumoto Ken Ebisawa Hirokazu Odaka Qazuya Wada
Astrophysical Journal 960(1) Jan 2024
Supersoft X-ray sources (SSSs) are white dwarf (WD) binaries that radiate almost entirely below ∼1 keV. Their X-ray spectra are often complex when viewed with the X-ray grating spectrometers, where numerous emission and absorption features are int...
Mayu Tominaga Masahiro Tsujimoto Ken Ebisawa Teruaki Enoto Kimitake Hayasaki
Astrophysical Journal 958(1) Nov 2023
Circinus X-1 (Cir X-1) is a neutron star binary with an elliptical orbit of 16.6 days. The source is unique for its extreme youth, providing a key to understanding early binary evolution. However, its X-ray variability is too complex to reach a cl...
R. Imamura H. Awaki M. Tsujimoto S. Yamada F. S. Porter C. A. Kilbourne R. L. Kelley Y. Takei
Journal of Low Temperature Physics 211(5-6) 426-433 Jun 2023
Low-temperature detectors often use mechanical coolers as part of the cooling chain in order to reach sub-Kelvin operating temperatures. The microphonic noise caused by the mechanical coolers is a general and inherent issue for these detectors. We...
Tomoki Omama Masahiro Tsujimoto Ken Ebisawa Misaki Mizumoto
Astrophysical Journal 945(2) Mar 2023
MAXI J1820+070 is a transient black hole binary discovered on 2018 March 11. The unprecedented rich statistics brought by the NICER X-ray telescope allow detailed timing analyses up to ∼1 kHz uncompromised by photon shot noise. To estimate the tim...
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 75(1) 177-186 Feb 2023
gamma Cas analog sources are a subset of Be stars that emit intense and hard X-ray emission. Two competing ideas for their X-ray production mechanism are (a) the magnetic activities of the Be star and its disk and (b) the accretion from the Be sta...
Director General, ISAS