2003年10月12日日曜日
2003年2月1日土曜日
2002年11月1日金曜日
High resolution soft X-ray spectroscopy of the elliptical galaxy NGC 5044. Results from the reflection grating spectrometer on-board XMM-Newton
Published on A&A, 2003
abstract
The results from an X-ray spectroscopic study of the giant elliptical galaxy NGC 5044 in the center of a galaxy group are presented. The line dominated soft X-ray spectra (mainly Fe-L and O VIII
) from the diffuse gas are resolved for the first time in this system with the Reflection Grating Spectrometers on-board XMM-Newton and provide a strong constraint on the temperature structure. The spectra integrated over 2
(
20 kpc) in full-width can be described by a two temperature plasma model of 0.7 keV and 1.1 keV. Most of the latter component is consistent with originating from off-center regions. Compared to the isobaric cooling flow prediction, the observation shows a clear cut-off below a temperature of 
keV. Furthermore, the Fe and O abundances within the central 10-20 kpc in radius are accurately measured to be 
and 
times the solar ratios, respectively. The observed cut-off temperature of this galaxy and other central galaxies in galaxy groups and clusters are compared with the scale of the galaxy and properties of the surrounding intra-cluster medium. Based on this comparison, the origin of the lack of predicted cool emission is discussed.
abstract
The results from an X-ray spectroscopic study of the giant elliptical galaxy NGC 5044 in the center of a galaxy group are presented. The line dominated soft X-ray spectra (mainly Fe-L and O VIII
) from the diffuse gas are resolved for the first time in this system with the Reflection Grating Spectrometers on-board XMM-Newton and provide a strong constraint on the temperature structure. The spectra integrated over 2 (20 kpc) in full-width can be described by a two temperature plasma model of 0.7 keV and 1.1 keV. Most of the latter component is consistent with originating from off-center regions. Compared to the isobaric cooling flow prediction, the observation shows a clear cut-off below a temperature of keV. Furthermore, the Fe and O abundances within the central 10-20 kpc in radius are accurately measured to be and times the solar ratios, respectively. The observed cut-off temperature of this galaxy and other central galaxies in galaxy groups and clusters are compared with the scale of the galaxy and properties of the surrounding intra-cluster medium. Based on this comparison, the origin of the lack of predicted cool emission is discussed. Key words: galaxies: individual: NGC 5044 - galaxies: clusters: general - galaxies: abundances - X-rays: galaxies: clusters
2001年9月13日木曜日
XMM-Newton observations of the cluster of galaxies Abell 496
Accepted on A&A in 2001
abstract
The results from XMM-Newton observations of the relaxed cluster of galaxies Abell 496 are presented. The spatially-resolved X-ray spectra taken by the European Photon Imaging Cameras show a temperature drop and a Fe abundance increase in the intra-cluster medium (ICM) towards the cD galaxy at the cluster center. The abundances of Si and S also show a central enhancement. High resolution soft X-ray spectra obtained with the Reflection Grating Spectrometers provides a strong constraint on the temperature structure in the central cool plasma. Furthermore, the O abundance at the cluster core is accurately measured based on the O VIII
line detected with the RGS. Contrary to the Si, S, and Fe abundances, the O abundance is radially constant over the cluster.
abstract
The results from XMM-Newton observations of the relaxed cluster of galaxies Abell 496 are presented. The spatially-resolved X-ray spectra taken by the European Photon Imaging Cameras show a temperature drop and a Fe abundance increase in the intra-cluster medium (ICM) towards the cD galaxy at the cluster center. The abundances of Si and S also show a central enhancement. High resolution soft X-ray spectra obtained with the Reflection Grating Spectrometers provides a strong constraint on the temperature structure in the central cool plasma. Furthermore, the O abundance at the cluster core is accurately measured based on the O VIII
line detected with the RGS. Contrary to the Si, S, and Fe abundances, the O abundance is radially constant over the cluster. Key words: galaxies: clusters: individual: Abell 496 - galaxies: clusters: general - galaxies: abundances - X-rays: galaxies: clusters
2001年1月26日金曜日
X-Ray Probing of the Central Regions of Clusters of Galaxies
Makishima, Kazuo; Ezawa, Hajime; Fukuzawa, Yasushi; Honda, Hirohiko; Ikebe, Yasushi; Kamae, Tuneyoshi; Kikuchi, Ken'ich; Matsushita, Kyoko; Nakazawa, Kazuhiro; Ohashi, Takaya, et al.
日本天文学会欧文研究報告論文賞受賞
2006年度
http://adsabs.harvard.edu/abs/2001PASJ...53..401M
日本天文学会欧文研究報告論文賞受賞
2006年度
http://adsabs.harvard.edu/abs/2001PASJ...53..401M
2000年10月1日日曜日
X-ray spectroscopy of the cluster of galaxies Abell 1795 with XMM-Newton
Accepted on A&A in 2001.
Abstract
The initial results from XMM-Newton observations of the rich cluster of galaxies Abell 1795 are presented. The spatially-resolved X-ray spectra taken by the European Photon Imaging Cameras (EPIC) show a temperature drop at a radius of
200 kpc from the cluster center, indicating that the ICM is cooling. Both the EPIC and the Reflection Grating Spectrometers (RGS) spectra extracted from the cluster center can be described by an isothermal model with a temperature of 4 keV. The volume emission measure of any cool component (VIII Lyman 
line was detected with the RGS from the cluster core. The O abundance and its ratio to Fe at the cluster center is 0.2-0.5 and 0.5-1.5 times the solar value, respectively.
http://adsabs.harvard.edu/abs/2001A%26A...365L..87T
citation papers
http://goo.gl/4iwcJC
Abstract
The initial results from XMM-Newton observations of the rich cluster of galaxies Abell 1795 are presented. The spatially-resolved X-ray spectra taken by the European Photon Imaging Cameras (EPIC) show a temperature drop at a radius of
200 kpc from the cluster center, indicating that the ICM is cooling. Both the EPIC and the Reflection Grating Spectrometers (RGS) spectra extracted from the cluster center can be described by an isothermal model with a temperature of 4 keV. The volume emission measure of any cool component (VIII Lyman line was detected with the RGS from the cluster core. The O abundance and its ratio to Fe at the cluster center is 0.2-0.5 and 0.5-1.5 times the solar value, respectively.http://adsabs.harvard.edu/abs/2001A%26A...365L..87T
citation papers
http://goo.gl/4iwcJC
2000年2月1日火曜日
A new life in SRON, Utrecht, NL
On 2000-2, I moved to SRON, Utrecht, the Netherlands.
I got a post-doc position to work on XMM-Newton RGS instrument and data of X-ray clusters.
I worked as a member of the RGS team along with Drs. J.S.Kaastra, J.W.den Herder, and C. de Vries, J.Bleeker and other staff.
I had worked at SRON for three years. I liked this position very much.
I got a post-doc position to work on XMM-Newton RGS instrument and data of X-ray clusters.
I worked as a member of the RGS team along with Drs. J.S.Kaastra, J.W.den Herder, and C. de Vries, J.Bleeker and other staff.
I had worked at SRON for three years. I liked this position very much.
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