相关论文: Applications for edge detection techniques using C…
This paper presents the analysis of a combined 134 ks {\it Chandra} data of a peculiar galaxy cluster Abell 2626. This study confirms the earlier detection of the east cavity at $\sim$13 kpc and reports detection of a new cavity at $\sim$39…
Wind-fed supergiant X-ray binaries are precious laboratories not only to study accretion under extreme gravity and magnetic field conditions, but also to probe still highly debated properties of massive star winds. These includes the…
We present a detailed X-ray study of the intracluster medium (ICM) of the nearby, cool-core galaxy cluster Abell 478, with Chandra and XMM observations. Using a wavelet smoothing hardness analysis, we derive detailed temperature maps of…
XMM-Newton, with its high throughput and excellent spatial and spectral resolution, is an ideal instrument for spectro-imaging observation of clusters. Presented here is an XMM-Newton mosaic observation of A2163, from which a new radial…
We present a non-parametric method to measure inhomogeneities in the intracluster medium (ICM) from X-ray observations of galaxy clusters. Analysing mock Chandra X-ray observations of simulated clusters, we show that our new method enables…
We present a search for nuclear X-ray emission in the brightest cluster galaxies (BCGs) of a sample of groups and clusters of galaxies extracted from the Chandra archive. The exquisite angular resolution of Chandra allows us to obtain…
Identification of Abell 3120 as a galaxy cluster has recently been questioned with alternative suggestions including: a fossil remnant of a group merger, non-thermal emission from a radio galaxy, and projected emission from of a filamentary…
One of the most unique phenomena in the Galactic center region is the existence of numerous long and narrow filamentary structures within a few hundred parsecs of Sgr A$^{\star}$. While more than one than one hundred radio filaments have…
To better understand the mechanism or mechanisms that lead to AGN activity today, we measure the X-ray AGN fraction in a new sample of nearby clusters and examine how it varies with galaxy properties, projected cluster-centric radius, and…
We discuss two themes from Chandra observations of galaxies and clusters. First, we describe the effects of radio-emitting plasmas or ``bubbles'', inflated by active galactic nuclei, on the hot X-ray emitting gaseous atmospheres in galaxies…
X-ray observations with Chandra and XMM are providing valuable new measurements of the baryonic and dark matter content of groups and clusters. Masses of cD clusters obtained from X-ray and gravitational lensing studies generally show good…
We use XMM-Newton observations of the cluster of galaxies A133 to study the X-ray spectrum of the intracluster medium (ICM). We find a cold front to the southeast of the cluster core. From the pressure profile near the cold front, we derive…
We analyzed 200 ks of Chandra ACIS observations of the merging galaxy cluster A2142 to examine its prominent cold fronts in detail. We find that the southern cold front exhibits well-developed Kelvin-Helmholtz (KH) eddies seen in the sky…
We report on the detection of dark matter in the cluster of galaxies Abell~2163 using the weak gravitational distortion of background galaxies, and an analysis of the cluster X-ray emission. We find that while the qualitative distributions…
The recent detection with Chandra of two warm-hot intergalactic medium (WHIM) filaments toward Mrk 421 by Nicastro et al. provides a measurement of the bulk of the "missing baryons" in the nearby universe. Since Mrk 421 is a bright X-ray…
Using the X-ray data from \ASCA, spectral and spatial properties of the intra-cluster medium (ICM) of the cD cluster Abell 1795 are studied, up to a radial distance of $\sim 12'$ ($\sim 1.3$ $h_{50}^{-1}$ kpc). The ICM temperature and…
Recent observations have revealed interstellar features that apparently connect energetic activity in the central region of our Galaxy to its halo. The nature of these features, however, remains largely uncertain. We present a Chandra…
The use of galaxy clusters to constrain cosmology is limited in part due to uncertainties in derived cluster masses, which often depend on the gas temperature. Unfortunately, there exists a longstanding discrepancy in temperature…
The question of the X-ray background has been largely settled over the last 10 years using the ROSAT satellite. About 70-80 % of the soft X-ray background was resolved into discrete sources, which are mainly X-ray and optically unobscured…
We have used a 50.4 ksec Chandra obsffervation to examine the galaxy cluster Abell 115 (z=0.1971). The X-ray surface brightness distribution shows a merger of 2 sub-clusters with substantial off-axis motion. The northern sub-cluster moves…