Takayuki Tamura

X-ray Spectroscopy of the Core of the Perseus Cluster with Suzaku: Elemental Abundances in the Intracluster Medium (2009)

Tamura, Takayuki, Maeda, Y., Mitsuda, K., Fabian, A. C., Sanders, J. S., Furuzawa, A., ...

The results from Suzaku observations of the central region of the Perseus cluster are presented. Deep exposures with the X-ray Imaging Spectrometer provide high quality X-ray spectra from the...

Suzaku Observations of Abell 1795: Cluster Emission to R_200 (2009)

Bautz, Marshall W., Miller, Eric D., Sanders, Jeremy S., Arnaud, Keith A., Mushotzky, Richard F., Porter, F. Scott, ...

We report Suzaku observations of the galaxy cluster Abell 1795 that extend to r_200 ~ 2 Mpc, the radius within which the mean cluster mass density is 200 times the cosmic critical density. These...

Abstract Parallel Database Processing on a 100 Node PC Cluster: Cases for Decision Support Query Processing and Data Mining (2009)

Takayuki Tamura, Masato Oguchi, Masaru Kitsuregawa

We developed a PC cluster system consists of 100 PCs. Each PC employs the 200MHz Pentium Pro CPU and is connected with others through an ATM switch. We picked up two kinds of data intensive...

DEWS2006 3A-i6 Finding Thai Web Pages in Foreign Web Spaces� (2008)

Kulwadee Somboonviwat, Takayuki Tamura, Masaru Kitsuregawa

Abstract While the Web has been increasingly recognized as a culturally valuable social artifact, many nations endeavor to create national Web archives for long term preservation. However, due to its...

Suzaku Observations of the cluster of galaxies Abell 2052 (2008)

Tamura, Takayuki, Mitsuda, Kazuhisa, Takei, Yoh, Yamasaki, Noriko Y., ITOH, Akiharu, Hayashida, Kiyoshi, ...

The results from Suzaku XIS observations of the relaxed cluster of galaxies Abell2052 are presented. Offset pointing data are used to estimate the Galactic foreground emission in the direction to the...

On the lack of strong O-line excess in the Coma cluster outskirts from Suzaku (2008)

Takei, Yoh, Miller, Eric D., Bregman, Joel N., Kimura, Shunsuke, Ohashi, Takaya, Mitsuda, Kazuhisa, ...

About half of the baryons in the local Universe are thought to reside in the so-called warm-hot intergalactic medium (WHIM) at temperatures of 0.1-10 million K. Thermal soft excess emission in the...

Preliminary Experimental Results of a Parallel Association Rule Mining on ATM connected PC Clusters (2007)

Masato Oguchi, Takahiko Shintani, Takayuki Tamura, Masaru Kitsuregawa

Until recently, workstations were overwhelmingly superior to personal computers in terms of performance. However, recent PC technology has dramatically increased its CPU, main memory, and cache...

Suzaku Observation of HCG 62: Temperature, Abundance, and Extended Hard X-ray Emission Profiles (2007)

Tokoi, Kazuyo, Sato, Kosuke, Ishisaki, Yoshitaka, Ohashi, Takaya, Yamasaki, Noriko Y., Nakazawa, Kazuhiro, ...

We present results of 120 ks observation of a compact group of galaxies HCG~62 ($z=0.0145$) with Suzaku XIS and HXD-PIN\@. The XIS spectra for four annular regions were fitted with two temperature...

X-Ray Study of Temperature and Abundance Profiles of the Cluster of Galaxies Abell 1060 with Suzaku (2007)

Sato, Kosuke, Yamasaki, Noriko Y., Ishida, Manabu, Ishisaki, Yoshitaka, Ohashi, Takaya, Kawahara, Hajime, ...

We carried out observations of the central and 20' east offset regions of the cluster of galaxies Abell 1060 with Suzaku. Spatially resolved X-ray spectral analysis has revealed temperature and...

Warm-Hot Intergalactic Medium Associated with the Coma Cluster (2006)

Takei, Yoh, Henry, J. Patrick, Finoguenov, Alexis, Mitsuda, Kazuhisa, Tamura, Takayuki, Fujimoto, Ryuichi, ...

We present our XMM-Newton RGS observations of X Comae, an AGN behind the Coma cluster. We detect absorption by NeIX and OVIII at the redshift of Coma with an equivalent width of 3.3+/-1.8 eV and...

Suzaku Observations of the Centaurus Cluster: Absence of Bulk Motions in the Intracluster Medium (2006)

Ota, Naomi, Fukazawa, Yasushi, Fabian, Andrew C., Kanemaru, Takehiro, Kawaharada, Madoka, Kawano, Naomi, ...

The Centaurus cluster (z=0.0104) was observed with the X-ray Imaging Spectrometer (XIS) onboard the Suzaku X-ray satellite in three pointings, one centered on the cluster core and the other two...

Suzaku observation of the metallicity distribution in the intracluster medium of the Fornax cluster (2006)

Matsushita, Kyoko, Fukazawa, Yasushi, Hughes, John P., Kitaguchi, Takao, Makishima, Kazuo, Nakazawa, Kazuhiro, ...

The metallicity distribution in the Fornax cluster was studied with the XIS instrument onboard the Suzaku satellite. K-shell lines of O and Mg were resolved clearly, and the abundances of O, Mg, Si,...

Search for Oxygen Emission from Warm-Hot Intergalactic Medium around A2218 with Suzaku (2006)

Takei, Yoh, Ohashi, Takaya, Henry, J. Patrick, Mitsuda, Kazuhisa, Fujimoto, Ryuichi, Tamura, Takayuki, ...

We searched for redshifted O emission lines from the possible warm-hot intergalactic medium (WHIM) surrounding the cluster of galaxies A2218 at z=0.1756 using the XIS instrument on Suzaku. This...

Temperature and entropy profiles of nearby cooling flow clusters observed with XMM-Newton (2004)

Piffaretti, Rocco, Jetzer, Philippe, Kaastra, Jelle, Tamura, Takayuki

We investigate temperature and entropy profiles of 13 nearby cooling flow clusters observed with the EPIC cameras of XMM-Newton. When normalized and scaled by the virial radius the temperature...

High Resolution X-ray Spectroscopic Constraints on Cooling-Flow Models (2003)

Peterson, John R., Kahn, Steven M., Paerels, Frits B. S., Kaastra, Jelle S., Tamura, Takayuki, Bleeker, Johan A. M., ...

We present XMM-Newton Reflection Grating Spectrometer observations of X-ray clusters and groups of galaxies. We demonstrate the failure of the standard cooling-flow model to describe the soft X-ray...

X-Ray Probing of the Central Regions of Clusters of Galaxies (2001)

Makishima, Kazuo, Ezawa, Hajime, Fukazawa, Yasushi, Honda, Hirohiko, Ikebe, Yasushi, Kamae, Tuneyoshi, ...

Results of ASCA X-ray study of central regions of medium-richness clusters of galaxies are summarized, emphasizing differences between cD and non-cD clusters. The intra-cluster medium (ICM) is likely...

X-ray Measurements of the Gravitational Potential Profile in the Central Region of the Abell 1060 Cluster of Galaxies (2000)

Tamura, Takayuki, Makishima, Kazuo, Fukazawa, Yasushi, Ikebe, Yasushi, Xu, Haiguang

X-ray spectral and imaging data from ASCA and ROSAT were used to measure the total mass profile in the central region of Abell 1060, a nearby and relatively poor cluster of galaxies. The ASCA X-ray...

Two-Phased Intra-Cluster Medium in the Centaurus Cluster of Galaxies (1999)

Ikebe, Yasushi, Makishima, Kazuo, Fukazawa, Yasushi, Tamura, Takayuki, Xu, Haiguang, Ohashi, Takaya, ...

ASCA and ROSAT data of the Centaurus cluster were analyzed. A central excess in the radial brightness profile is found in the hard energy band up to 10keV. This requires a deeper central potential...

Parallel SQL Based Association Rule Mining on Large Scale PC Cluster: Performance Comparison with Directly Coded C Implementation (1999)

Iko Pramudiono, Takahiko Shintani, Takayuki Tamura, Masaru Kitsuregawa

. Data mining is becoming increasingly important since the size of databases grows even larger and the need to explore hidden rules from the databases becomes widely recognized. Currently database...

ASCA Measurements of Silicon and Iron Abundances in the Intracluster Medium (1998)

Fukazawa, Yasushi, Makishima, Kazuo, Tamura, Takayuki, Ezawa, Hajime, Xu, Haiguang, Ikebe, Yasushi, ...

We analyzed the ASCA X-ray data of 40 nearby clusters of galaxies, whose intracluster-medium temperature distributes in the range of 0.9--10 keV. We measured the Si and Fe abundances of the...

Parallel Database Processing on a 100 Node PC Cluster: Cases for Decision Support Query Processing and Data Mining (1997)

Takayuki Tamura, Masato Oguchi, Masaru Kitsuregawa

We developed a PC cluster system consists of 100 PCs. Each PC employs the 200MHz Pentium Pro CPU and is connected with others through an ATM switch. We picked up two kinds of data intensive...

Implementation And Performance Evaluation Of The Parallel Relational Database Server SDC-II (1996)

Takayuki Tamura, Yoshihisa Ogawa, Minoru Nakamura, Masaru Kitsuregawa

This paper presents the implementation and performance evaluation of the SDC-II, the Super Database Computer II. The SDC-II is a highly parallel relational database server, which consists of eight...