Dynamical history of a binary cluster: Abell 3653

We study the dynamical structure of a bimodal galaxy cluster Abell 3653 at z = 0.1089 using optical and X-ray data. Observations include archival data from the Anglo-Australian Telescope, X-ray observatories XMM–Newton and Chandra. We draw a global picture for A3653 using galaxy density, X-ray luminosity and temperature maps. The galaxy distribution has a regular morphological shape at the 3 Mpc size. The galaxy density map shows an elongation in the east–west direction, which perfectly aligns with the extended diffuse X-ray emission. We detect two dominant groups around the two brightest cluster galaxies (BCGs). BCG1 (z = 0.1099) can be associated with the main cluster A3653E, and a foreground subcluster A3653W is concentrated at BCG2 (z = 0.1075). Both X-ray peaks are dislocated from the BCGs by ∼35 kpc, which suggest an ongoing merger process. We measure the subcluster gas temperatures of 4.67 and 3.66 keV, respectively. Two-body dynamical analysis shows that A3653E and A3653W are very likely gravitationally bound (93.5 per cent probability). The highly favoured scenario suggests that the two subclusters have a mass ratio of 1.4 and are colliding close to the plane of sky (α = 17.61°) at 2400 km s−1, and will undergo core passage in 380 Myr. The temperature map also significantly shows a shock-heated gas (6.16 keV) between the subclusters, which confirms the supersonic infalling scenario.Large scale structure and cosmologyHigh Energy Astrophysic

ASCA and XMM-Newton Observations of A2029

The X-ray data of A2029 obtained with XMM-Newton show no evidence of an embedded AGN in the central region of this cluster, which was suggested from the analysis of restored ASCA image data, although some hot spots are seen within or around the central cD galaxy. The absence of AGN at the cluster center is consistentent with the result of Chandra observations. Radial profiles of the iron abundance and the 2D (surface) temperature obtained from the XMM-Newton data are in good agreement with the Chandra data as a whole.Comment: 8 pages, 13 figures, accepted for publication in Advances in Space Researc

Suzaku Observations of Ejecta-Dominated Galactic Supernova Remnant G346.6-0.2

We present here the results of the X-ray analysis of Galactic supernova remnant G346.6-0.2 observed with {\it Suzaku}. K-shell emission lines of Mg, Si, S, Ca and Fe are detected clearly for the first time. Strong emission lines of Si and S imply that X-ray emission nature of G346.6-0.2 is ejecta-dominated. The ejecta-dominated emission is well fitted with a combined model consisting of thermal plasma in non-equilibrium ionization and a non-thermal component, which can be regarded as synchrotron emission with a photon index of $\Gamma$ $\sim 0.6$. Absorbing column density of $N_{\rm H}\sim2.1\times10^{22}$ ${\rm cm^{-2}}$ is obtained from the best-fitting implying a high-density medium, high electron temperature of $kT_{\rm e}\sim1.2$ keV, and ionization timescale of $n_{\rm e}t\sim2.9\times10^{11}$ ${\rm cm^{-3}s}$ indicating that this remnant may be far from full ionization equilibrium. The relative abundances from the ejecta show that the remnant originates from a Type Ia supernova explosion.Comment: 7 pages, 4 figur

{\it Suzaku} observation of Galactic supernova remnant CTB 37A (G348.5+0.1)

We present here the results of the observation of CTB 37A obtained with the X-ray Imaging Spectrometer onboard the {\it Suzaku} satellite. The X-ray spectrum of CTB 37A is well fitted by two components, a single-temperature ionization equilibrium component (VMEKAL) with solar abundances, an electron temperature of $kT_{\rm e}\sim0.6$ keV, absorbing column density of $N_{\rm H}\sim3\times10^{22}$ ${\rm cm^{-2}}$ and a power-law component with photon index of $\Gamma$ $\sim 1.6$. The X-ray spectrum of CTB 37A is characterized by clearly detected K-shell emission lines of Mg, Si, S, and Ar. The plasma with solar abundances supports the idea that the X-ray emission originates from the shocked interstellar material. The ambient gas density, and age of the remnant are estimated to be $\sim1f^{-1/2}$${\rm cm^{-3}}$ and $\sim3\times10^{4}f^{1/2}$ yr, respectively. The center-filling X-ray emission surrounded by a shell-like radio structure and other X-ray properties indicate that this remnant would be a new member of mixed-morphology supernova remnant class

Keys to Cosmology - Clusters of Galaxies

We review several aspects of clusters of galaxies and their application to cosmology. We present first results of numerical simulations of the dynamics of the intra-cluster gas and of different interaction processes between cluster galaxies and the intra-cluster gas. In particular metallicity maps are very useful to determine the importance of the different interaction processes. Also mass determination methods and possible sources for uncertainties in the measurements are shown.Comment: Invited talk given at the Vulcano Workshop 2003 "Multifrequency Behaviour of High Energy Cosmic Sources", Chin. J. Astron. Astrophys., F. Giovannelli (ed.), 10 page

Chandra Observations of the Cl1604 Supercluster at z=0.9: Evidence for an Overdensity of Active Galactic Nuclei

We present the results of Chandra observations of the Cl1604 supercluster at z~0.9. The system is the largest structure mapped at redshifts approaching unity, containing at least eight spectroscopically confirmed galaxy clusters and groups. Using two 50-ksec ACIS-I pointings we examine both the X-ray point source population and the diffuse emission from individual clusters in the system. We find a 2.5\sigma excess of point sources detected in the hard band (2-10 keV) relative to the number of sources found in blank fields observed by Chandra. No such excess is observed in the soft band (0.5-2 keV). The hard-band source density is 1.47 times greater than that of a blank field, in agreement with the previously reported correlation between overdensity amplitude and cluster redshift. Using a maximum likelihood technique we have matched 112 of the 161 detected X-ray point sources to optical counterparts and found 15 sources that are associated with the supercluster. All 15 sources have rest-frame luminosities consistent with emission from active galactic nuclei (AGN). We find that the supercluster AGN largely avoid the densest regions of the system and are instead distributed on the outskirts of massive clusters or within poorer clusters and groups. We have also detected diffuse emission from two of the eight clusters and groups in the system, clusters Cl1604+4304 and Cl1604+4314. The systems have bolometric luminosities of 1.43x10^44 and 8.20x10^43 h70^-2 erg s^-1 and gas temperatures of 3.50 (+1.82-1.08) and 1.64 (+0.65-0.45) keV, respectively. Using updated velocity dispersions, we compare the properties of these systems to the cluster scaling relations followed by other X-ray and optically selected galaxy clusters at high redshift.Comment: 24 pages, 14 figures, submitted to Ap

X-ray Picture of Superclusters of Galaxies

Galaxies gravitationally attract each other and form galaxy groups (similar to 50) or galaxy clusters (> 100). Nevertheless galaxy clusters are not the end of structure formation. Clusters further get together and form Superclusters. Recent studies have shown that the Universe forms cosmic filaments and voids. The superclusters are the intersection points of these filaments. In this work we present an analysis of SCC100 and Shapley supercluster members. Using X-ray data we try to understand the mutual interactions between individual clusters. Since they are the best representatives of the Universe, we try to address large scale properties of the universe

PROBING THE COSMIC FILAMENTS BY MEANS OF X-RAY OBSERVATIONS

Recent observations and numerical simulations show that galaxies are not distributed in the Universe randomly. They are placed like the pearls of a necklace. The matter is spread into the space in the form of cosmic filaments and voids. The intersection regions of these cosmic filaments are what we observe as "clusters of galaxies". In this work we selected 9 clusters of galaxies (A1644, A1736, A3528, A3530, A3532, A3556, A3558, A3560, A3562) from SHAPLEY super cluster region, the largest concentration of galaxies in our nearby Universe. The XMM-Newton and Chandra archival data are used for the analysis. We interpret the morphology of the clusters in the region and gravitational perturbations as a result of close encountering in the Shapley. The cosmic filaments and webs are portrayed from the Shapley super cluster region analysis results