Search Publications
A search for a keV signature of radiatively decaying dark matter with Suzaku XIS observations of the X-ray diffuse background
Mitsuda, Kazuhisa; Yamasaki, Noriko Y.; Sekiya, Norio
We performed the deepest search for an X-ray emission line at between 0.5 and 7 keV from non-baryonic dark matter by the Suzaku XIS. Dark matter associated with the Milky Way was selected as the target to obtain the best signal-to-noise ratio. From the Suzaku archive, we selected 187 data sets of blank-sky regions that were dominated by the X-ray …
Scale heights and equivalent widths of the iron K-shell lines in the Galactic diffuse X-ray emission
Koyama, Katsuji; Nobukawa, Masayoshi; Uchiyama, Hideki +2 more
This paper reports the analysis of the X-ray spectra of the Galactic diffuse X-ray emission (GDXE) in the Suzaku archive. The fluxes of the Fe I Kα (6.4 keV), Fe XXV Heα (6.7 keV), and Fe XXVI Lyα (6.97 keV) lines are separately determined. From the latitude distributions, we confirm that the GDXE is decomposed into the Galactic center (GCXE), the…
Suzaku spectra of a Type-II supernova remnant, Kes 79
Takahashi, Tadayuki; Koyama, Katsuji; Lee, Shiu-Hang +1 more
This paper reports on results of a Suzaku observation of the supernova remnant (SNR) Kes 79 (G33.6+0.1). The X-ray spectrum is best fitted by a two-temperature model: a non-equilibrium ionization (NEI) plasma and a collisional ionization equilibrium (CIE) plasma. The NEI plasma is spatially confined within the inner radio shell with kT ∼ 0.8 keV, …
Search for gas bulk motions in eight nearby clusters of galaxies with Suzaku
Ota, Naomi; Yoshida, Hiroko
To search for bulk motions of the intracluster medium, we analyzed X-ray spectra taken with the Suzaku satellite, and measured the Doppler shift of the Fe-K line emission from eight nearby clusters of galaxies with various X-ray morphologies. In the cores of the Centaurus and Perseus clusters, the gas bulk velocity does not exceed the sound veloci…
Evidence for a 36 ks phase modulation in the hard X-ray pulses from the magnetar 1E 1547.0-5408
Enoto, Teruaki; Makishima, Kazuo; Nakazawa, Kazuhiro +4 more
The Suzaku data for the highly variable magnetar 1E 1547.0-5408, obtained during the 2009 January activity, were reanalyzed. The 2.07 s pulsation, detected in the 15-40 keV HXD data, was found to exhibit phase modulation, which can be modeled by a sinusoid with a period of 36.0^{+4.5}_{-2.5}ks and an amplitude of 0.52 ± 0.14 s. While the effect is…
Origin of the broad iron line feature and the soft X-ray variation in Seyfert galaxies
Ebisawa, Ken; Mizumoto, Misaki; Inoue, Hajime +4 more
Many Seyfert galaxies are known to exhibit significant X-ray spectral variations and seemingly broad iron K-emission line features. In this paper, we show that the "variable partial covering model," which has been successfully proposed for MCG -6-30-15 (Miyakawa et al. 2012, PASJ, 64, 140) and 1H 0707-495 (Mizumoto et al. 2014, PASJ, 66, 122), can…
New identification of the mixed-morphology supernova remnant G298.6-0.0 with possible gamma-ray association
Petre, Robert; Terada, Yukikatsu; Bamba, Aya +4 more
We present an X-ray analysis on the Galactic supernova remnant (SNR) G298.6-0.0 observed with Suzaku. The X-ray image shows a center-filled structure inside a radio shell, implying that this SNR can be categorized as a mixed-morphology (MM) SNR. The spectrum is well reproduced by a single-temperature plasma model in ionization equilibrium, with a …
Recombining plasma in the remnant of a core-collapsed supernova, Kes 17
Koyama, Katsuji; Uchida, Hiroyuki; Nobukawa, Masayoshi +4 more
We report on Suzaku results concerning Kes 17, a Galactic mixed-morphology supernova remnant. The X-ray spectrum of the whole Kes 17 is well explained by a pure thermal plasma, in which we found Lyα of Al XIII and Heα of Al XII, Ar XVII, and Ca XIX lines for the first time. The abundance pattern and the plasma mass suggest that Kes 17 is a remnant…
Suzaku study on the ejecta of the supernova remnant G272.2-3.2
Katsuda, Satoru; Koyama, Katsuji; Uchida, Hiroyuki +5 more
We report reanalyses of the Suzaku observations of the Galactic supernova remnant (SNR) G272.2-3.2, for which previous studies were limited below 3 keV. With careful data reduction and background subtraction, we discover the K-shell lines of Ar, Ca, and Fe above 3 keV. The X-ray spectrum of G272.2-3.2 consists of two components, a low-temperature …
Suzaku observations of a shock front tracing the western edge of the giant radio halo in the Coma Cluster
Allen, Steven W.; Takahashi, Tadayuki; Ichinohe, Yuto +5 more
We present the results of new Suzaku observations of the Coma Cluster, the X-ray brightest, nearby, merging system hosting a well-studied, typical giant radio halo. It has been previously shown that, on the western side of the cluster, the radio brightness shows a much steeper gradient compared to other azimuths. XMM-Newton and Planck revealed a s…