Search Publications
X-ray and infrared diagnostics of nearby active galactic nuclei with MAXI and AKARI
Nakagawa, Takao; Baba, Shunsuke; Isobe, Naoki +5 more
Nearby active galactic nuclei were diagnosed in the X-ray and mid-to-far infrared wavelengths with Monitor of All-sky X-ray Image (MAXI) and the Japanese infrared observatory AKARI, respectively. One hundred of the X-ray sources listed in the second release of the MAXI all-sky X-ray source catalog are currently identified as non-blazar-type active…
Origin of the X-ray broad iron spectral feature in GRS 1915+105
Tsujimoto, Masahiro; Ebisawa, Ken; Mizumoto, Misaki +1 more
The X-ray spectrum of GRS 1915+105 is known to have a "broad iron spectral feature" in the spectral hard state. Similar spectral features are often observed in active galactic nuclei (AGNs) and other black-hole binaries (BHBs), and several models have been proposed for explaining it. In order to distinguish spectral models, time variation provides…
Image stacking analysis of SDSS galaxies with AKARI Far-Infrared Surveyor maps at 65 µm, 90 µm, and 140 µm
Doi, Yasuo; Takita, Satoshi; Ootsubo, Takafumi +4 more
We perform image stacking analysis of Sloan Digital Sky Survey (SDSS) photometric galaxies over the AKARI Far-Infrared Surveyor maps at 65 µm, 90 µm, and 140 µm. The resulting image profiles are decomposed into the central galaxy component (single term) and the nearby galaxy component (clustering term), as a function of the r-ban…
Suzaku observation of a high-entropy cluster Abell 548W
Makishima, Kazuo; Nakazawa, Kazuhiro; Gu, Liyi +4 more
Abell 548W, one of the galaxy clusters located in the Abell 548 region, has about an order of magnitude lower X-ray luminosity compared to ordinal clusters in view of the well-known intracluster medium (ICM) temperature vs. X-ray luminosity (kT-LX) relation. The cluster hosts a pair of diffuse radio sources to the northwest and north, b…
Suzaku observations of two diffuse hard X-ray source regions, G22.0+0.0 and G23.5+0.1
Bamba, Aya; Yamauchi, Shigeo; Sumita, Mayu
G22.0+0.0 and G23.5+0.1 are diffuse hard X-ray sources discovered in the ASCA Galactic Plane Survey. We present Suzaku results of spectral analysis for these sources. G22.0+0.0 is confirmed to be a largely extended emission. Its spectra were represented by a highly absorbed power-law model with a photon index of 1.7 ± 0.3 and a moderately absorbed…
Iron emission line from the spiral galaxy M 101
Yamauchi, Shigeo
Archival Suzaku data of the face-on spiral galaxy M 101 were analyzed. An intense emission line at 6.72^{+0.10}_{-0.12}keV was detected in the central region. This line is identified with a K-line from He-like iron, which indicates the existence of a thin thermal plasma with a temperature of several keV. The iron line luminosity within the central…
Suzaku confirms NGC 3660 is an unabsorbed Seyfert 2
Nandra, Kirpal; Ueda, Yoshihiro; Bianchi, Stefano +3 more
An enigmatic group of objects, unabsorbed Seyfert 2s may have intrinsically weak broad line regions, obscuration in the line of sight to the BLR but not to the X-ray corona, or so much obscuration that the X-ray continuum is completely suppressed and the observed spectrum is actually scattered into the line of sight from nearby material. NGC 3660 …
Matched-filtering line search methods applied to Suzaku data
Enoto, Teruaki; Ohashi, Takaya; Yamada, Shin'ya +2 more
A detailed search for emission and absorption lines and an assessment of their upper limits are performed for Suzaku data. The method utilizes a matched-filtering approach to maximize the signal-to-noise ratio for a given energy resolution, which could be applicable to many types of line search. We first applied it to well-known active galactic nu…
XMM-Newton and Suzaku spectroscopic studies of unidentified X-ray sources towards the Galactic bulge: 1RXS J180556.1-343818 and 1RXS J173905.2-392615
Maeda, Yoshitomo; Mori, Hideyuki; Ueda, Yoshihiro
With XMM-Newton and Suzaku observations, for the first time, we acquired broad-band spectra of two unidentified X-ray sources towards the Galactic bulge: 1RXS J180556.1-343818 and 1RXS J173905.2-392615. The 1RXS J180556.1-343818 spectrum in the 0.3-7 keV band was explained by X-ray emission that originated from an optically-thin thermal plasma wit…