A deep Chandra observation of the cooling core cluster Abell 4059 (A4059) is presented. Previous studies have found two X-ray cavities in the central regions of A4059 together with a ridge of X-ray emission 20kpc south-west of the cluster center. These features are clearly related to the radio galaxy PKS2354-35 which resides in the cD galaxy. Our new data confirm these previous findings and strengthen previous suggestions that the south-western ridge is colder and denser than, but in approximate pressure equilibrium with, the surrounding ICM atmosphere. In addition, we find evidence for a weak shock that wraps around the north and east sides of the cavity structure. Our data allow us to map the 2-dimensional distribution of metals in the ICM of A4059 for the first time. We find that the SW ridge possesses an anomalously high (super-solar) metalicity. The unusual morphology, temperature structure and metal distribution all point to significant asymmetry in the ICM atmosphere prior to the onset of radio-galaxy activity. Motivated by the very high metalicity of the SW ridge, we hypothesize that the ICM asymmetry was caused by the extremely rapid stripping of metal enriched gas from a starburst galaxy that plunged through the core of A4059. Furthermore, we suggest that the onset of powerful radio-galaxy activity in the cD galaxy may have been initiated by this starburst/stripping event, either via the tidal-shocking of cold gas native to the cD galaxy, or the accretion of cold gas that had been stripped from the starburst galaxy.
From ROSAT data, the bright X-ray cluster Abell 85 was found to show a roughly symmetrical shape, on to which are superimposed several features, among which: (1) a blob or group of galaxies falling on to the main cluster, with the gas in the impact region probably hotter and the galaxies in that zone showing enhanced star formation; (2) a filament, either diffuse or made of small groups of galaxies, extending at least 4 Mpc from the cluster (Durret et al. 1998). Preliminary results obtained from XMM-Newton and Chandra observations of Abell 85 and its filament will be presented.
We present preliminary results of imaging and spectral analysis of the cluster A496 with the S3 chip on-board the Chandra satellite. We confirm the presence of a cooling flow and radial gradients in elemental abundances. The cluster's core has clear signs of substructures (sharp edges, cavities), similar to those recently found in other cooling flow clusters. The O/Fe ratio distribution indicates that the gas in the core of the cluster is significantly enriched by SN Ia ejecta.
We present the analysis of 30 ksec of Chandra observations of the galaxy cluster Abell 1835. Overall, the X-ray image shows a relaxed morphology, although we detect substructure in in the inner 30 kpc radius. Spectral analysis shows a steep drop in the X-ray gas temperature from ~12 keV in the outer regions of the cluster to ~4 keV in the core. The Chandra data provide tight constraints on the gravitational potential of the cluster which can be parameterized by a Navarro, Frenk & White (1997) model. The X-ray data allow us to measure the X-ray gas mass fraction as a function of radius, leading…
We present results from a Chandra observation of Abell 1060, the nearby cluster of galaxies. The ACIS-I image shows that the central cusp-like structure, previously seen from PSPC, is caused mainly by an emission from the central elliptical galaxy NGC 3311. We confirmed that the central region is remarkably isothermal with a temperature of 3.2 keV, based on the spectral fits for fine pixels. An extended region in the northeast of NGC 3311 indicates high iron abundance. The surface brightness profile excluding the central galaxy, NGC 3311, can be fitted only by a double beta model, with core ra…
We analyze the mass content of the massive strong-lensing cluster Abell 586 ($z = 0.17$). We use optical data (imaging and spectroscopy) obtained with the Gemini Multi-Object Spectrograph (GMOS) mounted on the 8-m Gemini-North telescope, together with publicly available X-ray data taken with the \textit{Chandra} space telescope. Employing different techniques -- velocity distribution of galaxies, weak gravitational lensing, and X-ray spatially resolved spectroscopy -- we derive mass and velocity dispersion estimates from each of them. All estimates agree well with each other, within a 68% conf…
We present results from an analysis of a Chandra observation of the cluster of galaxies Abell 3581. We discover the presence of a point-source in the central dominant galaxy which is coincident with the core of the radio source PKS 1404-267. The emission from the intracluster medium is analysed, both as seen in projection on the sky, and after correcting for projection effects, to determine the spatial distribution of gas temperature, density and metallicity. We find that the cluster, despite hosting a moderately powerful radio source, shows a temperature decline to around 0.4Tmax within the c…
We present data from a Chandra observation of the nearby cluster of galaxies Abell 576. The core of the cluster shows a significant departure from dynamical equilibrium. We show that this core gas is most likely the remnant of a merging subcluster, which has been stripped of much of its gas, depositing a stream of gas behind it in the main cluster. The unstripped remnant of the subcluster is characterized by a different temperature, density and metalicity than that of the surrounding main cluster, suggesting its distinct origin. Continual dissipation of the kinetic energy of this minor merger …
We present data from a Chandra observation of the nearby cluster of galaxies Abell 576. The core of the cluster shows a significant departure from dynamical equilibrium. We show that this core gas is most likely the remnant of a merging subcluster, which has been stripped of much of its gas, depositing a stream of gas behind it in the main cluster. The unstripped remnant of the subcluster is characterized by a different temperature, density and metalicity than that of the surrounding main cluster, suggesting its distinct origin. Continual dissipation of the kinetic energy of this minor merger …
We present a new estimate of the projected X-ray mass of Abell 1689 observed with Chandra, in an attempt to clarify the issue of whether or not there exists a discrepancy between X-ray and gravitational lensing mass estimates claimed in previous investigations based on {\it Einstein}, {\it ROSAT} and {\it ASCA} observations. A particular attention is paid to examining if there is an offset between X-ray centroid and central dominant cD galaxy, which may be an indicator of the presence of local dynamical activities of intracluster gas in the central core and therefore, explain the discrepancy b…
We present Chandra observations of the galaxy cluster A4059. We find strong evidence that the FR-I radio galaxy PKS 2354-35 at the center of A4059 is inflating cavities with radii ~20 kpc in the intracluster medium, similar to the situation seen in Perseus A and Hydra A. We also find evidence for interaction between the intracluster medium and PKS 2354-35 on small scales in the very center of the cluster. Arguments are presented suggesting that this radio galaxy has faded significantly in radio power (possibly from an FR-II state) over the past 10^8 yrs.
We present a Chandra observation of the merging cluster of galaxies Abell 2744. The cluster shows strong evidence for an ongoing major merger which we believe to be responsible for the radio halo. X-ray emission and temperature maps of the cluster, combined with the spatial and redshift distribution of the galaxies, indicate a roughly north-south axis for the merger, with a significant velocity component along the line of sight. The merger is occurring at a very large velocity, with M = 2-3. In addition, there is a small merging subcluster toward the northwest, unrelated to the major merger, w…
We present results from an analysis of two Chandra observations of the rich, nearby galaxy cluster Abell 2199. We find evidence (having corrected for projection effects) for radial gradients in temperature and metallicity in the X-ray emitting gas: the temperature drops from kT~4.2 keV at R=200 kpc to 1.6 keV within R=5 kpc of the centre. The metallicity rises from ~0.3 solar at R=200 kpc to ~0.7 solar at R=30 kpc before dropping to 0.3 solar within the central 5 kpc. We find evidence for structure in the surface brightness distribution associated with the central radio source 3C338. No eviden…
We present results from an observation of the luminous cluster of galaxies Abell 2204 using the Chandra X-ray Observatory. We show the core of the cluster has a complex morphological structure, made up of a high density core (n_e~0.2 cm^-3) with flat surface brightness, a surrounding central plateau, a tail-like feature, wrapping around to the east, and an unusual radio source. A temperature map and deprojected-profile shows that the temperature rises steeply outside these regions, until around ~100 kpc where it drops, then rises again. Abundance maps and profiles show that there is a correspo…
In our search for ``hidden'' AGN we present results from a Chandra observation of the nearby cluster Abell 2255. Eight cluster galaxies are associated with point-like X-ray emission, and we classify these galaxies based on their X-ray, radio, and optical properties. At least three are associated with active galactic nuclei (AGN) with no optical signatures of nuclear activity, with a further two being potential AGN. Of the potential AGN, one corresponds to a galaxy with a post-starburst optical spectrum. The remaining three X-ray detected cluster galaxies consist of two starbursts and an ellipt…
We present an analysis of a Chandra observation of Abell 2034. The cluster has multiple signatures of an ongoing merger, including a cold front and probable significant heating of the intracluster medium above its equilibrium temperature. We find no evidence for the large cooling rate previously determined for the cluster, and in fact find it to be roughly isothermal, though with numerous small-scale inhomogeneities, out to a radius of ~700 kpc. The cold front appears to be in the process of being disrupted by gas dynamic instability and perhaps by shock heating. We find weak evidence for Inve…
We present a Chandra observation of Abell 2052, a cooling flow cluster with a central cD that hosts the complex radio source 3C 317. The data reveal ``holes'' in the X-ray emission that are coincident with the radio lobes. The holes are surrounded by bright ``shells'' of X-ray emission. The data are consistent with the radio source displacing and compressing, and at the same time being confined by, the X-ray gas. The compression of the X-ray shells appears to have been relatively gentle and, at most, slightly transonic. The pressure in the X-ray gas (the shells and surrounding cooler gas) is a…
We present results from the Chandra X-ray observation of Abell 13, a galaxy cluster that contains an unusual noncentral radio source, also known as a radio relic. This is the first pointed X-ray observation of Abell 13, providing a more sensitive study of the properties of the X-ray gas. The X-ray emission from Abell 13 is extended to the northwest of the X-ray peak and shows substructure indicative of a recent merger event. The cluster X-ray emission is centered on the bright galaxy H of Slee et al. 2001. We find no evidence for a cooling flow in the cluster. A knot of excess X-ray emission i…
We present a detailed analysis of the XMM-Newton and Chandra observations of Abell 2626 focused on the X-ray and radio interactions. Within the region of the radio mini-halo (~70 kpc), there are substructures which are probably produced by the central radio source and the cooling core. We find that there is no obvious correlation between the radio bars and the X-ray image. The morphology of Abell 2626 is more complex than that of the standard X-ray radio bubbles seen in other cool core clusters. Thus, Abell 2626 provides a challenge to models for the cooling flow -- radio source interaction. W…
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 cluster velocity dispersion. We present new wide-field Chandra X-ray Observatory observations of Abell 85, Abell 754 and the background cluster Abell 89B out to their virial radii. Out of seventeen X-ray sources associated with galaxies in these clusters, we classify seven as X-ray AGN with L_{X,B} > 10^{41} erg/s. Only two of these would be classified as AGN…
We present the results of a Chandra observation of the cooling core cluster Abell 2063. Spectral analysis shows that there is cool gas (2 keV) associated with the cluster core, which is more than a factor of 2 cooler than the outer cluster gas (4.1 keV). There also is spectral evidence for a weak cooling flow, Mdot ~ 20 Msun/yr. The cluster exhibits a complex structure in the center that consists of several bright knots of emission, a depression in the emission to the north of the center of the cluster, and a shell of emission surrounding it. The depression in the X-ray emission is coincident …
We present an analysis of a highly asymmetric cluster merger from a Chandra observation of Abell 85. The merger shows significant disruption of the less massive subcluster from ram pressure effects. Nevertheless, a cold core, coincident with the cD galaxy, is observed to persist in the subcluster. We derive dynamical information from the motion of the cold core through the main cluster's ICM. Multiple derivations of the velocity of the core suggest a Mach number of M ~ 1.4 or v ~ 2150 km/s, though with substantial uncertainty. We construct a consistent kinematic model for the merger based on t…
Chandra ACIS-S observations of the galaxy cluster A3112 feature the presence of an excess of X-ray emission above the contribution from the diffuse hot gas, which can be equally well modeled with an additional non-thermal power-law model or with a low-temperature thermal model of low metal abundance. We show that the excess emission cannot be due to uncertainties in the background subtraction or in the Galactic HI column density. Calibration uncertainties in the ACIS detector that may affect our results are addressed by comparing the Chandra data to XMM MOS and PN spectra. While differences be…
We present an analysis of a 41 ks Chandra observation of the merging cluster Abell 2065 with the ACIS-I detector. Previous observations with ROSAT and ASCA provided evidence for an ongoing merger, but also suggested that there were two surviving cooling cores, which were associated with the two cD galaxies in the center of the cluster. The Chandra observation reveals only one X-ray surface brightness peak, which is associated with the more luminous, southern cD galaxy. The gas related with that peak is cool and displaced slightly from the position of the cD. The data suggest that this cool mat…
We present X-ray spatial and spectral analysis of the Chandra data from the central 400 kpc (H0 = 50 km/s/Mpc) of the cluster of galaxies Abell 1795. The plasma temperature rises outwards by a factor of 3, whereas the iron abundance decreases by a factor of 4. The spatial distribution of Oxygen, Neon, Sulphur, Silicon and Iron shows that supernovae Type Ia dominate the metal enrichment process of the cluster plasma within the inner 150 kpc. Resolving both the gas density and temperature in 9 radial bins, we recover the gravitational mass density profile and show that it flattens within 100 kpc…
We use Chandra data to map the gas temperature in the central region of the merging cluster A2142. The cluster is markedly nonisothermal; it appears that the central cooling flow has been disturbed but not destroyed by a merger. The X-ray image exhibits two sharp, bow-shaped, shock-like surface brightness edges or gas density discontinuities. However, temperature and pressure profiles across these edges indicate that these are not shock fronts. The pressure is reasonably continuous across these edges, while the entropy jumps in the opposite sense to that in a shock (i.e. the denser side of the…
Abell 1758 was classified as a single rich cluster of galaxies by Abell, but a ROSAT observation showed that this system consists of two distinct clusters (A1758N and A1758S) separated by approximately $8\arcmin$ (a projected separation of 2 Mpc in the rest frame of the clusters). Only a few galaxy redshifts have been published for these two clusters, but the redshift of the Fe lines in the Chandra and XMM-Newton spectra shows that the recessional velocities of A1758N and A1758S are within 2,100 km s$^{-1}$. Thus, these two clusters most likely form a gravitationally bound system, but our imag…
We have obtained high spatial resolution temperature and abundance profiles for the galaxy cluster Abell 2029 with the Chandra ACIS-S instrument. Our observations reveal that the spectra are well-fit by a single-phase gas in each annulus. While the temperature of the intracluster medium drops from ~9 keV at 3 arcmin (260 kpc) to 3 keV in the central 5 arcsec (5 kpc) of the cluster, there is no evidence for gas emitting at temperatures below 3 keV. The addition of a cooling flow component does not improve the fits, despite previous claims for a massive cooling flow. There is also no evidence fo…
We present spatially-resolved X-ray spectroscopy of the luminous lensing cluster Abell 2390, using observations made with the Chandra observatory. The temperature of the X-ray gas is shown to rise with increasing radius within the central ~200 kpc of the cluster, and then remain approximately isothermal, with kT =11.5^{+1.5}_{-1.6} keV, out to the limits of the observations at r~1.0 Mpc. The total mass profile determined from the Chandra data has a form in good agreement with the predictions from numerical simulations. Using the parameterization of Navarro, Frenk & White (1997), we measure a s…
We present a Chandra observation of the cooling flow cluster Abell 262. Spectral fits show that the intracluster medium (ICM) in A262 cools by a factor of three from 2.7 keV to 0.9 keV at the cluster center. A mass deposition rate of Mdot = 19 +6/-5 Msun/yr is measured. Complex structure is found in the very inner regions of the cluster, including knots of emission and a clear deficit of emission to the east of the cluster center. The bright X-ray structures are located in the same regions as optical line emission, indicating that cooling to low temperatures has occurred in these regions. The …
A Chandra observation of the non-cooling flow cluster A 1060 has confirmed that the hot intracluster medium has fairly uniform distributions of temperature and metal abundance from a radius of about 230 kpc to the central 5 kpc region (H_0= 75 km/s/Mpc). The radial temperature profile shows a broad peak at 30-40 kpc from the center at a level ~20% higher than that in the outer region. Assuming spatially uniform temperature and abundance distributions, we derived a 3-dimensional density structure by iteratively correcting the beta model, and obtained the central gas density to be 8.2^{+1.8}_{-1…
We present the results of a spatially-resolved spectroscopic analysis of the galaxy cluster Abell 496 with the S3 chip on-board the Chandra satellite. We confirm the presence of a central positive temperature gradient consistent with a cooling flow, but with a minimum gas temperature of ~0.5-0.9 keV. The cluster also exhibits sharp edges in gas density and temperature which are consistent with "cold front" substructures. The iron abundance profile is not radially symmetric relative to the cluster center. Towards the direction of the most prominent (northerly) cold front, the iron abundance is …
We present an analysis of a Chandra observation of the massive, nearby galaxy cluster Abell 2319. A sharp surface brightness discontinuity--suggested by previous, lower angular resolution X-ray imaging--is clearly visible in the ACIS image. This roughly 300kpc feature suggests that a major merger is taking place with a significant velocity component perpendicular to the line of sight. The cluster emission-weighted mean temperature is 11.8+/-0.6kev, somewhat higher than previous temperature measurements. The Chandra temperature map of A2319 reveals substructure resembling that anticipated based…
We present results from a 38 ks Chandra X-ray observation of the z=0.059 galaxy cluster A1991. The cluster has a bright X-ray core and a central temperature gradient that declines inward from 2.7 keV at 130 kpc to approximately 1.6 keV at the cluster center. The radiative cooling time of the gas in the inner 10 kpc is about 0.5 Gyr, and rises to 1 Gyr at a radius of 20 kpc. The cooling rate of the gas within the latter radius is less than about 25 solar mass/yr. The Chandra ACIS-S3 image shows that the intracluster medium has an asymmetric surface brightness distribution with respect to the ce…
(abridged) We present a detailed reanalysis of the Chandra data for the galaxy cluster Abell 4059 and its central radio galaxy, PKS2354-35. We also present new 1.4GHz and 4.7GHz CnB-array radio data from the Very Large Array (VLA), as well as a short archival WFPC2 image from the Hubble Space Telescope. The presence of a strong interaction between this radio galaxy and the intracluster medium (ICM) was suggested by Huang & Sarazin (1998) on the basis of a short observation by the High Resolution Imager on ROSAT, and confirmed in our preliminary analysis of the Chandra/ACIS-S data. In particula…
We present the analysis of a Chandra observation of the galaxy cluster Abell 133, which has a cooling flow core, a central radio source, and a diffuse, filamentary radio source which has been classified as a radio relic. The X-ray image shows that the core has a complex structure. The most prominent feature is a "tongue" of emission which extends from the central cD galaxy to the northwest and partly overlaps the radio relic. One possibility is that this tongue is produced by Kelvin-Helmholtz (KH) instabilities through the interaction between the cold gas around the cD galaxy and hot intraclus…
We use Chandra data to derive a detailed gas temperature map of the nearby, hot, merging galaxy cluster A754. Combined with the X-ray and optical images, the map reveals a more complex merger geometry than previously thought, possibly involving more than two subclusters or a cool gas cloud sloshing independently from its former host subcluster. In the cluster central region, we detect spatial variations of the gas temperature on all linear scales, from 100 kpc (the map resolution) and up, which likely remain from a merger shock passage. These variations are used to derive an upper limit on eff…
Deep VLA 1.4 GHz radio continuum imaging of Abell 2255 is presented. This cluster is among the better nearby candidates for rich cluster-cluster merger systems, with evidence including an elongated X-ray morphology, the presence of a radio halo, and substructure present in its galaxy distribution. Our radio observations reach an rms sensitivity of ~40 uJy/beam, enabling us to detect (at 5 sigma) star formation rates as low as 1.4 M(sun)/year from the center of the cluster out to a radial distance of 3 Mpc. The radio data are complemented by optical imaging and a large spectroscopic database, a…
We present the results of a {\it Chandra} observation of the central region of Abell 3112. This cluster has a powerful radio source in the center and was believed to have a strong cooling flow. The X-ray image shows that the intracluster medium (ICM) is distributed smoothly on large scales, but has significant deviations from a simple concentric elliptical isophotal model near the center. Regions of excess emission appear to surround two lobe-like radio-emitting regions. This structure probably indicates that hot X-ray gas and radio lobes are interacting. From an analysis of the X-ray spectra …
We present results from two observations (combined exposure of ~17 ks) of galaxy cluster A2218 using the Advanced CCD Imaging Spectrometer on board the Chandra X-ray Observatory that were taken on October 19, 1999. Using a Raymond-Smith single temperature plasma model corrected for galactic absorption we find a mean cluster temperature of kT = 6.9+/-0.5 keV, metallicity of 0.20+/-0.13 (errors are 90 % CL) and rest-frame luminosity in the 2-10 keV energy band of 6.2x10^{44} erg/s in a LambdaCDM cosmology with H_0=65 km/s/Mpc. The brightness distribution within 4'.2 of the cluster center is well…
Wide-angle tail (WAT) radio sources are often found in the centers of galaxy clusters where intracluster medium (ICM) ram pressure may bend the lobes into their characteristic C-shape. We examine the low redshift (z=0.1035) cluster Abell 1446, host to the WAT radio source 1159+583. The cluster exhibits possible evidence for a small-scale cluster-subcluster merger as a cause of the WAT radio source morphology. This evidence includes the presence of temperature and pressure substructure along the line that bisects the WAT as well as a possible wake of stripped interstellar material or a disrupte…
We report on a spatially resolved analysis of Chandra X-ray data on a nearby typical cooling flow cluster of galaxies 2A 0335+096, together with A 2199 for a comparison. As recently found in the cores of other clusters, the temperature around the central part of 2A 0335+096 is 1.3--1.5 keV, which is higher than that inferred from the cooling flow picture. Furthermore, the absorption column density is almost constant against the radius in 2A 0335+096; there is no evidence of excess absorption up to 200--250 kpc. This indicates that no significant amount of cold material, which has cooled down, …
We present an analysis of the Chandra X-ray observation of Abell 2052, including large scale properties of the cluster as well as the central region which includes the bright radio source, 3C 317. We present temperature and abundance profiles using both projected and deprojected spectral analyses. The cluster shows the cooling flow signatures of excess surface brightness above a beta- model at the cluster center, and a temperature decline into the center of the cluster. The heavy element abundances initially increase into the center, but decline within 30 arcsec. Temperature and abundance maps…
We report the discovery of a 40 arcsec long X-ray filament in the core of the cluster of galaxies A1795. The feature coincides with an Halpha+NII filament found by Cowie et al in the early 1980s and resolved into at least 2 U-band filaments by McNamara et al in the mid 1990s. The (emission-weighted) temperature of the X-ray emitting gas along the filament is 2.5-3 keV, as revealed by X-ray colour ratios. The deprojected temperature will be less. A detailed temperature map of the core of the cluster presented. The cD galaxy at the head of the filament is probably moving through or oscillating i…
We have used a high resolution Chandra observation to examine the core mass distribution of the unusually regular cD cluster Abell 2029. This system is especially well-suited for analysis of its mass distribution under the assumption of hydrostatic equilibrium: it exhibits an undisturbed X-ray morphology and a single-phase ICM. We estimate the total mass, and the contributions of the gas and dark matter components from <3 arcsec to ~3 arcmin (<4.4-260 kpc, 0.001-0.1 r_vir). The gas density is well fitted by either a double beta-model, or a ``cusped'' beta-model. The temperature data are increa…
The structure of the universe is believed to have formed by clustering hierarchically from small to large scales. Much of this evolution occurs very slowly but at a few special times more, rapid, violent activity may occur as major subunits collide at high velocities. The Abell 2125 complex (z=0.247) appears to be undergoing such an event as shown by modeling of the optical velocity field and by the detection with the VLA of an unusually large number of associated radio active galaxies. We present an 80 ksec Chandra imaging of Abell 2125, together with extensive complementary multi-wavelength …
The cluster DC0107-46 (Abell 2877) lies within the Phoenix Deep Survey, made at 1.4 GHz with the Australia Telescope Compact Array. Of 89 known optical cluster members, 70 lie within the radio survey area. Of these 70 galaxies, 15 (21%) are detected, with luminosities as faint as 10^20 W/Hz. Spectroscopic observations are available for 14/15 of the radio-detected cluster galaxies. Six galaxies show only absorption features and are typical low-luminosity AGN radio sources. One galaxy hosts a Seyfert 2 nucleus, two are star-forming galaxies, and the remaining five may be star-forming galaxies, A…
We have analyzed the Chandra, BeppoSax, and ROSAT observations of Abell 754 and report evidence of a soft, diffuse X-ray component. The emission is peaked in the cluster center and is detected out to 8' from the X-ray center. Fitting a thermal model to the combined BeppoSax and PSPC spectra show excess emission below 1 keV in the PSPC and above 100 keV in the BeppoSax PDS. The source 26W20 is in the field of view of the PDS. The addition of a powerlaw with the spectral parameters measured by Silverman et al. (1998) for 26W20 successfully models the hard component in the PDS. The remaining exce…
We report the first X-ray detection of a proto-supermassive binary black hole at the centre of Abell 400. Using the Chandra ACIS, we are able to clearly resolve the two active galactic nuclei in 3C 75, the well known double radio source at the centre of Abell 400. Through analysis of the new Chandra observation of Abell 400 along with 4.5 GHz and 330 MHz VLA radio data, we will show new evidence that the Active Galactic Nuclei in 3C 75 are a bound system. Methods. Using the high quality X-ray data, we map the temperature, pressure, density, and entropy of the inner regions as well as the clust…
We present the Chandra analysis of the galaxy cluster A521 (z=0.247). The high resolution of the Chandra observation has allowed us to refine the original merging scenario proposed for A521, and to reveal new features in its X-ray emission. A521 has strongly substructured ICM density and temperature maps. Its X-ray diffuse emission is elongated along a NW/SE direction (SX2) and shows two major components, a main cluster and a northern group of galaxies. This latter is in turn substructured, showing a clump of cold and very dense gas centred on the BCG, and a northern tail aligned in the SX2 di…
Recent Chandra and XMM X-ray observations of rich clusters of galaxies have shown that the amount of hot gas which is cooling below ~1 keV is generally more modest than previous estimates. Yet, the real level of the cooling flows, if any, remains to be clarified by making observations sensitive to different temperature ranges. As a follow-up of the FUSE observations reporting a positive detection of the OVI doublet at 1032, 1038 Angstrom in the cluster of galaxies Abell 2597, which provided the first direct evidence for ~3x10^5 K gas in a cluster of galaxies, we have carried out sensitive spec…
I review Chandra's achievements in the last two years in AGN research. I concentrate on some topics of my interest; some others are reviewed in an accompanying article by K. Nandra. I comment briefly on the need to allow for the discovery space to ensure rapid progress in the field.
We present a dynamical analysis of the galaxy cluster Abell 1942 based on a set of 128 velocities obtained at the European Southern Observatory. Data on individual galaxies are presented and the accuracy of the determined velocities is discussed as well as some properties of the cluster. We have also made use of publicly available Chandra X-ray data. We obtained an improved mean redshift value z = 0.22513 \pm 0.0008 and velocity dispersion sigma = 908^{+147}_{-139} km/s. Our analysis indicates that inside a radius of ~1.5 h_{70}^{-1} Mpc (~7 arcmin) the cluster is well relaxed, without any rem…
The 2 Ms Chandra Deep Field-North survey provides the deepest view of the Universe in the 0.5--8.0 keV X-ray band. In this brief review we investigate the diversity of X-ray selected sources and focus on the constraints placed on AGNs (including binary AGNs) in high-redshift submm galaxies.
We present Chandra and VLA observations of two galaxy clusters, Abell 160 and Abell 2462, whose brightest cluster galaxies (BCGs) host wide angle tailed radio galaxies (WATs). We search for evidence of interactions between the radio emission and the hot, X-ray emitting gas, and test various jet termination models. We find that both clusters have cool BCGs at the cluster centre, and that the scale of these cores ~30-40kpc for both sources) is of approximately the same scale as the length of the radio jets. For both sources, the jet flaring point is coincident with a steepening in the host clust…
A previous analysis of the Chandra X-ray image of the center of the cooling core cluster Abell 2597 showed two ``ghost holes'' in the X-ray emission to the west and northeast of the central radio galaxy PKS 2322-123. Previous radio observations did not detect any radio emission coming from the interior of the X-ray holes. We present new low frequency radio observations of Abell 2597. At 330 MHz, radio emission extends into the interior of the western ghost bubble, but not the northeast one. Our re-analysis of the archival Chandra data shows evidence for an X-ray tunnel (elongated region of red…
We report the detection by Chandra of SMM J02399-0134 and SMM J02399-0136, two distant (z=1.06 and z=2.81, respectively) submillimeter sources gravitationally magnified by the galaxy cluster Abell 370. These are high-significance (> 7-sigma) X-ray detections of the high-redshift submillimeter source population. The X-ray positions are coincident with the optical positions to within one arcsecond. The X-ray spectra, while of low signal-to-noise ratio, are quite hard. Absorbed power law models with fixed photon indices of $Γ=2.0$ imply local absorbing columns $>2 \times 10^{23}$ cm$^{-2}$ and un…
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 A478, revealing a surprising amount of temperature structure. The broad band Chandra spectral fits yield temperatures which are significantly hotter than those from XMM, but the Fe ionization temperature shows good agreement. We show that the temperature discrepancy is slightly reduced when comparing spectra from regions selected to enclose nearly isothermal ga…
A comprehensive study of the effect of the cluster environment on the far- infrared (FIR)/radio correlation in nearby Abell clusters is presented. Using the cluster radio galaxy database from Miller & Owen (2001) and optical spectroscopy and high resolution radio images to remove AGN, we assess the FIR/radio correlation of cluster galaxies from the centers of the clusters out well past the classical Abell radius. The FIR/radio correlation is shown to hold quite well for star forming galaxies, and the FIR and radio fluxes for cluster AGN are also well correlated. In the case of AGN, the relativ…
We present soft X-ray results from observations with the Chandra HETGS of the Seyfert I AGN NGC 4593 and Mrk 509. We discuss the photoionized outflows associated with Seyfert I AGN in terms of their absorption spectral signatures and discuss their kinematics, column density and ionization state. We discuss the link between UV and X-ray absorbers in Mrk 509 (which was simultaneously observed with Chandra and HST/STIS. We also briefly discuss the possibility of absorption due to neutral Fe embedded in the warm absorber of NGC 4593 versus an interpretation of the data in terms soft X-ray relativi…
We combine bright XMM data with the Chandra Deep Field South observations in order to explore the behavior of the intrinsic AGN absorption, as a function of redshift and luminosity.Our sample consists of 359 sources selected in the hard 2-8 keV band, spanning the flux range 6\times10^{-16}-$3\times10^{-13} erg s^-1 cm^-2 with a high rate of spectroscopic or photometric redshift completeness (100 and 85 per cent respectively for the Chandra and XMM data. We derive the column density values using X-ray spectral fits. We find that the fraction of obscured AGN falls with increasing luminosity in a…
