Search Publications
The origin of recombining plasma and the detection of the Fe-K line in the supernova remnant W 28
Uchida, Hiroyuki; Tsuru, Takeshi Go; Tanaka, Takaaki +2 more
Overionized recombining plasmas (RPs) have been discovered from a dozen mixed-morphology (MM) supernova remnants (SNRs). However, their formation process is still under debate. As pointed out by many previous studies, spatial variations of plasma temperature and ionization state provide clues to understanding the physical origin of RPs. We report …
Suzaku and NuSTAR X-ray spectroscopy of γ Cassiopeiae and HD 110432
Tsujimoto, Masahiro; Hayashi, Takayuki; Kitaguchi, Takao +1 more
γ Cas and its dozen analogs comprise a small but distinct class of X-ray sources. They are early Be-type stars with an exceptionally hard thermal X-ray emission. The X-ray production mechanism has been under intense debate. Two competing ideas are (i) the magnetic activities in the Be star and its disk, and (ii) the mass accretion onto the unident…
Discovery of recombining plasma from the faintest GeV supernova remnant HB 21 and a possible scenario for cosmic rays escaping from supernova remnant shocks
Nakazawa, Kazuhiro; Koyama, Katsuji; Bamba, Aya +4 more
We present an X-ray study of the GeV gamma-ray supernova remnant (SNR) HB 21 with Suzaku. HB 21 is interacting with molecular clouds, and is the faintest in the GeV band among known GeV SNRs. We discovered strong radiative recombination continua of Si and S from the center of the remnant, which provide direct evidence of a recombining plasma (RP).…
Discovery of 6.4 keV line and soft X-ray emissions from G323.7-1.0 with Suzaku
Koyama, Katsuji; Matsumoto, Hironori; Nobukawa, Masayoshi +4 more
In this paper, the Suzaku X-ray data of the Galactic supernova remnant (SNR) candidate G323.7-1.0 are analyzed to search for X-ray emissions. Spatially extended enhancements in the 6.4 keV line and in soft X-rays are found inside or on the radio shell. The soft X-ray enhancement would be the hottest part of the shell-like X-ray emission along the …
Suzaku X-ray observations of the mixed-morphology supernova remnant CTB 1
Takahashi, Tadayuki; Uchida, Hiroyuki; Uchiyama, Yasunobu +6 more
We present an X-ray study of the mixed-morphology supernova remnant CTB 1 (G116.9+0.2) observed with Suzaku. The 0.6-2.0 keV spectra in the northeastern breakout region of CTB 1 are well represented by a collisional ionization-equilibrium plasma model with an electron temperature of ∼0.3 keV, whereas those in the southwestern inner-shell region ca…
Suzaku observations of low surface brightness cluster Abell 1631
Matsumoto, Hironori; Mitsuishi, Ikuyuki; Ota, Naomi +5 more
We present analysis results for a nearby galaxy cluster Abell 1631 at z = 0.046 using the X-ray observatory Suzaku. This cluster is categorized as a low X-ray surface brightness cluster. To study the dynamical state of the cluster, we conduct four-pointed Suzaku observations and investigate physical properties of the Mpc-scale hot gas associated w…
High entropy and evidence for a merger in the low surface brightness cluster Abell 2399
Mitsuishi, Ikuyuki; Ota, Naomi; Babazaki, Yasunori +4 more
We present results of the X-ray analyses of the nearby cluster of galaxies Abell 2399 (z = 0.058) using the XMM-Newton and Suzaku satellites. This cluster is classified as a low surface brightness (LSB) cluster. It has a bimodal structure in X-rays, and the X-ray-emission peaks are significantly offset from the peaks in gas temperature. By de-proj…
Energy-dependent intensity variation of the persistent X-ray emission of magnetars observed with Suzaku
Enoto, Teruaki; Ebisawa, Ken; Nakagawa, Yujin
The emission mechanism of magnetars is still controversial even though various observational and theoretical studies have been made. In order to investigate mechanisms of both the persistent X-ray emission and the burst emission of the magnetars, we propose a model in which the persistent X-ray emission consists of numerous micro-bursts of various…