- ID:
- ivo://CDS.VizieR/J/AJ/126/2740
- Title:
- X-ray emission of RASS Abell clusters
- Short Name:
- J/AJ/126/2740
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the X-ray emission for a complete sample of 288 Abell clusters spanning the redshift range 0.016<=z<=0.09 from the ROSAT All-Sky Survey. This sample is based on our 20cm VLA survey of nearby Abell clusters. We find an X-ray detection rate of 83%. We report cluster X-ray fluxes and luminosities and two different flux ratios indicative of the concentration and extent of the emission. We examine correlations between the X-ray luminosity, Abell richness, and Bautz-Morgan and Rood-Sastry cluster morphologies. We find a strong correlation between LX and cluster richness coupled with a dependence on the optical morphological type. These results are consistent with the observed scatter between X-ray luminosity and temperature and a large fraction of cooling flows. For each cluster field, we also report the positions, peak X-ray fluxes, and flux ratios of all X-ray peaks above 3{sigma} significance within a box of 2x2(h_75_)^-1^Mpc centered on Abell's position.
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- ID:
- ivo://CDS.VizieR/J/A+A/636/A15
- Title:
- X-ray galaxy cluster sample
- Short Name:
- J/A+A/636/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The isotropy of the late Universe and consequently of the X-ray galaxy cluster scaling relations is an assumption greatly used in astronomy. However, within the last decade, many studies have reported deviations from isotropy when using various cosmological probes; a definitive conclusion has yet to be made. New, effective and independent methods to robustly test the cosmic isotropy are of crucial importance. In this work, we use such a method. Specifically, we investigate the directional behavior of the X-ray luminosity-temperature (L_X_-T) relation of galaxy clusters. A tight correlation is known to exist between the luminosity and temperature of the X-ray-emitting intracluster medium of galaxy clusters. While the measured luminosity depends on the underlying cosmology through the luminosity distance D_L_, the temperature can be determined without any cosmological assumptions. By exploiting this property and the homogeneous sky coverage of X-ray galaxy cluster samples, one can effectively test the isotropy of cosmological parameters over the full extragalactic sky, which is perfectly mirrored in the behavior of the normalization A of the L_X_-T relation. To do so, we used 313 homogeneously selected X-ray galaxy clusters from the Meta-Catalogue of X-ray detected Clusters of galaxies. We thoroughly performed additional cleaning in the measured parameters and obtain core-excised temperature measurements for all of the 313 clusters. The behavior of the L_X_-T relation heavily depends on the direction of the sky, which is consistent with previous studies. Strong anisotropies are detected at a>=4{sigma} confidence level toward the Galactic coordinates (l, b)~(280{deg}, -20{deg}), which is roughly consistent with the results of other probes, such as Supernovae Ia. Several effects that could potentially explain these strong anisotropies were examined. Such effects are, for example, the X-ray absorption treatment, the effect of galaxy groups and low redshift clusters, core metallicities, and apparent correlations with other cluster properties, but none is able to explain the obtained results. Analyzing 10^5^ bootstrap realizations confirms the large statistical significance of the anisotropic behavior of this sky region. Interestingly, the two cluster samples previously used in the literature for this test appear to have a similar behavior throughout the sky, while being fully independent of each other and of our sample. Combining all three samples results in 842 different galaxy clusters with luminosity and temperature measurements. Performing a joint analysis, the final anisotropy is further intensified (~5{sigma}), toward (l, b)~(303{deg}, -27{deg}), which is in very good agreement with other cosmological probes. The maximum variation of D_L_ seems to be ~16+/-3% for different regions in the sky. This result demonstrates that X-ray studies that assume perfect isotropy in the properties of galaxy clusters and their scaling relations can produce strongly biased results whether the underlying reason is cosmological or related to X-rays. The identification of the exact nature of these anisotropies is therefore crucial for any statistical cluster physics or cosmology study.
- ID:
- ivo://CDS.VizieR/J/ApJ/799/60
- Title:
- X-ray galaxy clusters in the CFHTLS fields
- Short Name:
- J/ApJ/799/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) presents a unique data set for weak-lensing studies, having high-quality imaging and deep multiband photometry. We have initiated an XMM-CFHTLS project to provide X-ray observations of the brightest X-ray-selected clusters within the wide CFHTLS area. Performance of these observations and the high quality of CFHTLS data allow us to revisit the identification of X-ray sources, introducing automated reproducible algorithms, based on the multicolor red sequence finder. We have also introduced a new optical mass proxy. We provide the calibration of the red sequence observed in the Canada-France-Hawaii filters and compare the results with the traditional single-color red sequence and photo-z. We test the identification algorithm on the subset of highly significant XMM clusters and identify 100% of the sample. We find that the integrated z-band luminosity of the red sequence galaxies correlates well with the X-ray luminosity, with a surprisingly small scatter of 0.20dex. We further use the multicolor red sequence to reduce spurious detections in the full XMM and ROSAT All-Sky Survey (RASS) data sets, resulting in catalogs of 196 and 32 clusters, respectively. We made spectroscopic follow-up observations of some of these systems with HECTOSPEC and in combination with BOSS DR9 data. We also describe the modifications needed to the source detection algorithm in order to maintain high purity of extended sources in the shallow X-ray data. We also present the scaling relation between X-ray luminosity and velocity dispersion.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A4
- Title:
- 3 X-ray galaxy clusters radio images
- Short Name:
- J/A+A/634/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is well established that particle acceleration by shocks and turbulence in the intra-cluster medium can produce cluster-scale synchrotron emitting sources. However, the detailed physics of these particle acceleration processes is still not well understood. One of the main open questions is the role of fossil relativistic electrons that have been deposited in the intracluster medium (ICM) by radio galaxies. These synchrotron-emitting electrons are very difficult to study as their radiative lifetime is only tens of Myr at gigahertz frequencies, and they are therefore a relatively unexplored population. Despite the typical steep radio spectrum due to synchrotron losses, these fossil electrons are barely visible even at radio frequencies well below the gigahertz level. However, when a pocket of fossil radio plasma is compressed, it boosts the visibility at sub-gigahertz frequencies, creating what are known as radio phoenices. This compression can be the result of bulk motion and shocks in the ICM due to merger activity. In this paper we demonstrate the discovery potential of low-frequency radio sky surveys to find and study revived fossil plasma sources in galaxy clusters. We used the 150MHz TIFR GMRT Sky Survey (TGSS) and the 1.4GHz NVSS sky survey to identify candidate radio phoenices. A subset of three candidates was studied in detail using deep multi-band radio observations (LOFAR and GMRT), X-ray observations (Chandra or XMM-Newton), and archival optical observations. Two of the three sources are new discoveries. Using these observations, we identified common observational properties (radio morphology, ultra-steep spectrum, X-ray luminosity, dynamical state) that will enable us to identify this class of sources more easily, and will help us to understand the physical origin of these sources.
- ID:
- ivo://CDS.VizieR/J/A+A/535/A4
- Title:
- X-ray galaxy clusters study
- Short Name:
- J/A+A/535/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A precise understanding of the relations between observable X-ray properties of galaxy clusters and cluster mass is a vital part of the application of X-ray galaxy cluster surveys to test cosmological models. An understanding of how these relations evolve with redshift is just emerging from a number of observational data sets. The current literature provides a diverse and inhomogeneous picture of scaling relation evolution. We attempt to transform these results and the data on recently discovered distant clusters into an updated and consistent framework, and provide an overall view of scaling relation evolution from the combined data sets. We study in particular the most important scaling relations connecting X-ray luminosity, temperature, and cluster mass (M-T, L_X_-T, and M-L_X_) combining 14 published data sets supplemented with recently published data of distant clusters and new results from follow-up observations of the XMM-Newton Distant Cluster Project (XDCP) that adds new leverage to efficiently constrain the scaling relations at high redshift.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A130
- Title:
- X-ray halo of 33 clusters of galaxies images
- Short Name:
- J/A+A/585/A130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In high-resolution X-ray observations of the hot plasma in clusters of galaxies significant structures caused by AGN feedback, mergers, and turbulence can be detected. Many clusters have been observed by Chandra in great depth and at high resolution. Using archival data taken with the Chandra ACIS instrument the aim was to study thermodynamic perturbations of the X-ray emitting plasma and to apply this to better understand the thermodynamic and dynamic state of the intra cluster medium (ICM). We analyzed deep observations for a sample of 33 clusters with more than 100ks of Chandra exposure each at distances between redshift 0.025 and 0.45. The combined exposure of the sample is 8Ms. Fitting emission models to different regions of the extended X-ray emission we searched for perturbations in density, temperature, pressure, and entropy of the hot plasma. For individual clusters we mapped the thermodynamic properties of the ICM and measured their spread in circular concentric annuli. Comparing the spread of different gas quantities to high-resolution 3D hydrodynamic simulations, we constrain the average Mach number regime of the sample to Mach1D ~0.16+/-0.07. In addition we found a tight correlation between metallicity, temperature and redshift with an average metallicity of Z~0.3+/-0.1 Z(solar). This study provides detailed perturbation measurements for a large sample of clusters which can be used to study turbulence and make predictions for future X-ray observatories like eROSITA, Astro-H, and Athena.
- ID:
- ivo://CDS.VizieR/J/MNRAS/439/611
- Title:
- X-ray luminosities of SDSS DR7 clusters from RASS
- Short Name:
- J/MNRAS/439/611
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use ROSAT All Sky Survey broad-band X-ray images and the optical clusters identified from Sloan Digital Sky Survey Data Release 7 to estimate the X-ray luminosities around ~65000 candidate clusters with masses >~10^13^h-1^M_{sun}_ based on an optical to X-ray (OTX) code we develop. We obtain a catalogue with X-ray luminosity for each cluster. This catalogue contains 817 clusters (473 at redshift z<=0.12) with signal-to-noise ratio >3 in X-ray detection. We find about 65% of these X-ray clusters have their most massive member located near the X-ray flux peak; for the rest 35%, the most massive galaxy is separated from the X-ray peak, with the separation following a distribution expected from a Navarro-Frenk-White profile. We investigate a number of correlations between the optical and X-ray properties of these X-ray clusters, and find that the cluster X-ray luminosity is correlated with the stellar mass (luminosity) of the clusters, as well as with the stellar mass (luminosity) of the central galaxy and the mass of the halo, but the scatter in these correlations is large. Comparing the properties of X-ray clusters of similar halo masses but having different X-ray luminosities, we find that massive haloes with masses >~10^14^h^-1^M_{sun}_ contain a larger fraction of red satellite galaxies when they are brighter in X-ray. An opposite trend is found in central galaxies in relative low-mass haloes with masses <~10^14^h^-1^M_{sun}_ where X-ray brighter clusters have smaller fraction of red central galaxies. Clusters with masses >~10^14^h^-1^M_{sun}_ that are strong X-ray emitters contain many more low-mass satellite galaxies than weak X-ray emitters. These results are also confirmed by checking X-ray clusters of similar X-ray luminosities but having different characteristic stellar masses. A cluster catalogue containing the optical properties of member galaxies and the X-ray luminosity is available at http://gax.shao.ac.cn/data/Group.html.
- ID:
- ivo://CDS.VizieR/J/ApJ/554/L129
- Title:
- X-ray luminosity-velocity dispersion relation
- Short Name:
- J/ApJ/554/L129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We demonstrate that individual elliptical galaxies and clusters of galaxies form a continuous X-ray luminosity-velocity dispersion (L_X_-{sigma}) relation. Our samples of 280 clusters and 57 galaxies have L_X_ {prop.to}{sigma}^4.4^ and L_X_{prop.to}{sigma}^10^, respectively. This unified L_X_-{sigma} relation spans 8 orders of magnitude in L_X_ and is fully consistent with the observed and theoretical luminosity-temperature scaling laws. Our results support the notion that galaxies and clusters of galaxies are the luminous tracers of similar dark matter halos.
- ID:
- ivo://CDS.VizieR/J/AJ/130/445
- Title:
- X-ray-luminous galaxy cluster RX J0142.0+2131
- Short Name:
- J/AJ/130/445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric and spectroscopic study of stellar populations in the X-ray-luminous cluster of galaxies RX J0142.0+2131 at z=0.280. This paper analyzes the results of high signal-to-noise ratio spectroscopy, as well as g'-, r'-, and i'-band imaging, using the Gemini Multi-Object Spectrograph on Gemini North.
- ID:
- ivo://CDS.VizieR/J/MNRAS/457/4515
- Title:
- X-ray_peak-BCG offset for PSZ1 clusters
- Short Name:
- J/MNRAS/457/4515
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We want to characterize the dynamical state of galaxy clusters detected with the Sunyaev-Zeldovich (SZ) effect by Planck and compare them with the dynamical state of clusters selected in X-rays survey. We analysed a representative subsample of the Planck SZ catalogue, containing the 132 clusters with the highest signal to noise ratio and characterize their dynamical state using as an indicator the projected offset between the peak of the X-ray emission and the position of the Brightest cluster galaxy. We compare the distribution of this indicator for the Planck SZ-selected sample and three X-ray-selected samples (HIFLUGCS, MACS and REXCESS). The distributions are significantly different and the fraction of relaxed objects is smaller in the Planck sample (52+/-4 per cent) than in X-ray samples (~=74 per cent) We interpret this result as an indication of different selection effects affecting X-rays (e.g. 'cool core bias') and SZ surveys of galaxy clusters.
