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, …
Parallax of a Mira variable R Ursae Majoris studied with astrometric VLBI
Kurayama, Tomoharu; Honma, Mareki; Nakagawa, Akiharu +5 more
We have measured an annual parallax of the Mira variable R Ursae Majoris (R UMa) with the VLBI Exploration for Radio Astronomy (VERA). From the monitoring VLBI observations over a span of about two years, we detected H2O maser spots in the LSR velocity range from 37 to 42 km s-1. We derived an annual parallax of 1.97 ± 0.05 m…
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…
Investigating the relation between CO (3-2) and far-infrared luminosities for nearby merging galaxies using ASTE
Kaneko, Hiroyuki; Muto, Takayuki; Ueda, Junko +10 more
We present the new single-dish CO (3-2) emission data obtained toward 19 early-stage and 7 late-stage nearby merging galaxies using the Atacama Submillimeter Telescope Experiment (ASTE). Combining with the single-dish and interferometric data of galaxies observed in previous studies, we investigate the relation between the CO (3-2) luminosity (L^'…
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 …
Mid- and far-infrared properties of Spitzer Galactic bubbles revealed by the AKARI all-sky surveys
Yamagishi, Mitsuyoshi; Kaneda, Hidehiro; Fukui, Yasuo +9 more
We have carried out a statistical study on the mid- and far-infrared (IR) properties of Galactic IR bubbles observed by Spitzer. Using the Spitzer 8 µm images, we estimated the radii and covering fractions of their shells, and categorized them into closed, broken, and unclassified bubbles with our data analysis method. Then, using the AKARI …