A Deprojection Analysis of Abell 1650 with XMM-Newton  

作　　者：Shu-Mei Jia Yong Chen Li Chen 

机构地区：[1]Department of Astronomy, Beijing Normal University, Beijing 100875 [2]Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academyof Sciences, Beijing 100049

出　　处：《Chinese Journal of Astronomy and Astrophysics》2006年第2期181-196,共16页中国天文和天体物理学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China.

摘　　要：We revisit the XMM-Newton observation of the galaxy cluster Abell 1650 with a deprojection technique. We find that the radial deprojected spectra of Abell 1650 can be marginally fitted by a single-temperature model. In order to study the properties of the central gas, we fit the spectra of the central two regions with a two- temperature model. The fits then become significantly better and the cool gas about 1～2 keV can be connected with the gas cooling. Fitting the central spectrum （r≤1′） by using a cooling flow model with an isothermal component yields a small mass deposition rate of 10-7^＋11 M. yr^-1, while the standard cooling flow model can not fit this spectrum satisfactorily except that there exists a cut-off temperature having a level of about 3 keV. From the isothermal model we derive the deprojected electron density profile ne（r）, and then together with the deprojected temperature profile the total mass and gas mass fraction of cluster are also determined. We compare the properties of Abell 1650 with those of Abell 1835 （a large cooling flow cluster） and some other clusters, to explore the difference in properties between large and small cooling flow cluster, and what causes the difference in the cooling flow of different clusters. It has been shown that Abell 1835 has a steeper potential well and thus a higher electron density and a lower temperature in its center, indicating that the shape of the gravitational potential well in central region determines the cooling flow rates of clusters. We calculate the potential, internal and radiated energies of these two clusters, and find that the gas energies in both clusters are conserved during the collapsing stage.We revisit the XMM-Newton observation of the galaxy cluster Abell 1650 with a deprojection technique. We find that the radial deprojected spectra of Abell 1650 can be marginally fitted by a single-temperature model. In order to study the properties of the central gas, we fit the spectra of the central two regions with a two- temperature model. The fits then become significantly better and the cool gas about 1～2 keV can be connected with the gas cooling. Fitting the central spectrum （r≤1′） by using a cooling flow model with an isothermal component yields a small mass deposition rate of 10-7^＋11 M. yr^-1, while the standard cooling flow model can not fit this spectrum satisfactorily except that there exists a cut-off temperature having a level of about 3 keV. From the isothermal model we derive the deprojected electron density profile ne（r）, and then together with the deprojected temperature profile the total mass and gas mass fraction of cluster are also determined. We compare the properties of Abell 1650 with those of Abell 1835 （a large cooling flow cluster） and some other clusters, to explore the difference in properties between large and small cooling flow cluster, and what causes the difference in the cooling flow of different clusters. It has been shown that Abell 1835 has a steeper potential well and thus a higher electron density and a lower temperature in its center, indicating that the shape of the gravitational potential well in central region determines the cooling flow rates of clusters. We calculate the potential, internal and radiated energies of these two clusters, and find that the gas energies in both clusters are conserved during the collapsing stage.

关 键 词：galaxies： clusters： individual： Abell 1650 -galaxies： cooling flowsgalaxies： evolution - galaxies： intergalactic medium - X-rays： galaxies： clusters 

分 类 号：P156[天文地球—天文学]