Search Publications
Subaru Weak Lensing Study of Seven Merging Clusters: Distributions of Mass and Baryons
Umetsu, Keiichi; Okabe, Nobuhiro
We present and compare projected distributions of mass, galaxies, and the intracluster medium (ICM) for a sample of merging clusters of galaxies based on a joint weak-lensing, optical photometric, and X-ray analysis. Our sample comprised seven nearby Abell clusters, for which we had conducted systematic, deep imaging observations with Suprime-Cam …
Suzaku Observations of AWM 7 Cluster of Galaxies: Temperatures, Abundances, and Bulk Motions
Ishida, Manabu; Sato, Kosuke; Ohashi, Takaya +4 more
We carried out 3 observations of the cluster of galaxies AWM 7, for the central region and 20'-east and 20'-west offset regions, with Suzaku. Temperature and abundance profiles were measured out to 27' simeq 570 h70-1kpc, which corresponded to ∼0.35r180. The temperature of the intra-cluster medium (ICM) slightly de…
Suzaku Wide-Band X-Ray Spectroscopy of the Seyfert2 AGN in NGC 4945
Done, Chris; Isobe, Naoki; Gandhi, Poshak +13 more
Suzaku observed a nearby Seyfert2 galaxy, NGC 4945, which hosts one of the brightest active galactic nuclei above 20keV. Combining data from the two detectors aboard Suzaku, the AGN intrinsic nuclear emission and its reprocessed signals were observed simultaneously. The intrinsic emission is highly obscured with an absorbing column of ∼5×1024…
Suzaku Observation of the Metallicity in the Hot Interstellar Medium of the Isolated Elliptical Galaxy NGC 720
Fukazawa, Yasushi; Anabuki, Naohisa; Matsushita, Kyoko +3 more
The metal abundances in the interstellar medium of the isolated elliptical galaxy NGC 720 were studied with the CCD X-ray Imaging Spectrometer (XIS) aboard the Suzaku satellite. The high detection efficiency along with the excellent spectral resolution of the XIS allowed the K-shell lines of O and Mg to be clearly resolved, and the abundances of O…
Suzaku X-Ray Spectroscopy of a Peculiar Hot Star in the Galactic Center Region
Nagata, Tetsuya; Tsujimoto, Masahiro; Koyama, Katsuji +5 more
We present the results of a Suzaku study of a bright point-like source in the 6.7keV intensity map of the Galactic center region. We detected an intense FeXXV 6.7keV line with an equivalent width of ∼1keV as well as emission lines of highly ionized Ar and Ca from a spectrum obtained by the X-ray Imaging Spectrometer. The overall spectrum is descri…
Discovery of a Bright Transient Ultraluminous X-Ray Source, Suzaku J1305-4931 in NGC4945
Isobe, Naoki; Gandhi, Poshak; Makishima, Kazuo +5 more
An X-ray source, Suzaku J1305-4931, was discovered in the south-west arm of a nearby Seyfert II galaxy, NGC4945, at 0.5-10keV flux of 2.2×10-12erg cm-2 s-1 during a Suzaku observation conducted on 2006 January 15-17. It was undetectable in a shorter observation on 2005 August 22--23, with an upper limit of 1.7×10
Implication for Super-Critical Accretion Flow in the Narrow-Line Seyfert 1 Galaxy PKS 0558-504
Kunieda, Hideyo; Haba, Yoshito; Terashima, Yuichi +1 more
We present results from XMM-Newton observations of the narrow-line Seyfert 1 galaxy PKS0558-504. The 2-12keV X-ray spectra can be well-reproduced by a single power law with a photon index of ∼2.2. The extrapolation of this power law continuum into the lower energy band reveals the existence of a strong soft excess component. When we applied a mult…
XMM-Newton Observations of NGC 4051: Temporal Flux and Spectral Variability during Transition to the Faintest Phase in NGC 4051
Tsuruta, Sachiko; Liebmann, Andrew C.; Kunieda, Hideyo +2 more
We report on the results from temporal and spectral analyses of NGC 4051 observed with XMM-Newton. The X-ray variabilities in the higher-flux states are well explained by the combination of a variable, direct power law and a temporally stable, absorbed component. In low-flux states, however, spectral variations are mainly due to flux changes of th…
Suzaku Detection of an Intense X-Ray Flare from an A-Type Star, HD161084
Sugawara, Yasuharu; Maeda, Yoshitomo; Tsujimoto, Masahiro +4 more
We report on a serendipitous detection of an intense X-ray flare from the Tycho reference source on HD161084 during a Suzaku observation of the galactic center region for ∼20ks. The X-ray Imaging Spectrometer recorded a flare from this A1-type dwarf or subgiant star with a flux of ∼1.4 × 10-12 erg s-1 cm-2 (0.5--10…
Heavy Element Analysis of X-Ray Faint Elliptical Galaxies
Fukazawa, Yasushi; Tozuka, Miyako
Past ASCA and ROSAT observations could not support the general view that elliptical galaxies are sources of metals in the intracluster medium, since observational results have shown that X-ray faint elliptical galaxies exhibit too low metal abundances of hot interstellar medium (ISM). We investigated the radial profiles of the temperature and abun…