- 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.
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- 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.
- ID:
- ivo://CDS.VizieR/J/PASJ/56/965
- Title:
- X-ray properties of ASCA objects
- Short Name:
- J/PASJ/56/965
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Utilizing ASCA archival data of about 300 objects of elliptical galaxies, groups, and clusters of galaxies, we performed systematic measurements of the X-ray properties of hot gas in their systems, and compiled them in this paper. The steepness of the luminosity-temperature (LT) relation, L_X_{prop.to}(kT)^alpha^, in the range of kT~1.5-15keV is alpha=3.17+/-0.15, consistent with previous measurements.
- ID:
- ivo://CDS.VizieR/J/MNRAS/371/1777
- Title:
- X-ray properties of 3 EDisCS galaxy clusters
- Short Name:
- J/MNRAS/371/1777
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present XMM-Newton observations of three optically selected z>0.6 clusters from the European Southern Observatory (ESO) Distant Cluster Survey (EDisCS), comprising the first results of a planned X-ray survey of the full EDisCS high-redshift sample. The EDisCS clusters were identified in the Las Campanas Distant Cluster Survey as surface brightness fluctuations in the optical sky and their masses and galaxy populations are well described by extensive photometric and spectroscopic observations. We detect two of the three clusters in the X-ray and place a firm upper limit on diffuse emission in the third cluster field. We are able to constrain the X-ray luminosity and temperature of the detected clusters and estimate their masses. We find that the X-ray properties of the detected EDisCS clusters are similar to those of X-ray-selected clusters of comparable mass and --- unlike other high-redshift, optically selected clusters --- are consistent with the T-sigma and L_X_-sigma relations determined from X-ray-selected clusters at low redshift. The X-ray determined mass estimates are generally consistent with those derived from weak-lensing and spectroscopic analyses. These preliminary results suggest that the novel method of optical selection used to construct the EDisCS catalogue may, like selection by X-ray luminosity, be well suited for identification of relaxed, high-redshift clusters whose intracluster medium is in place and stable by z=0.8.
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/5473
- Title:
- X-ray-selected galaxy clusters BCG offsets
- Short Name:
- J/MNRAS/478/5473
- Date:
- 08 Feb 2022 11:49:23
- Publisher:
- CDS
- Description:
- We used optical imaging and spectroscopic data to derive substructure estimates for local Universe (z<0.11) galaxy clusters from two different samples. The first was selected through the Sunyaev-Zel'dovich (SZ) effect by the Planck satellite, and the second is an X-ray-selected sample. In agreement to X-ray substructure estimates, we found that the SZ systems have a larger fraction of substructure than the X-ray clusters. We have also found evidence that the higher mass regime of the SZ clusters, compared to the X-ray sample, explains the larger fraction of disturbed objects in the Planck data. Although we detect a redshift evolution in the substructure fraction, it is not sufficient to explain the different results between the higher-z SZ sample and the X-ray one. We have also verified a good agreement (~60 per cent) between the optical and X-ray substructure estimates. However, the best level of agreement is given by the substructure classification given by measures based on the brightest cluster galaxy (BCG), either the BCG-X-ray centroid offset, or the magnitude gap between the first and second BCGs. We advocate the use of those two parameters as the most reliable and cheap way to assess cluster dynamical state. We recommend an offset cut-off ~0.01xR_500_ to separate relaxed and disturbed clusters. Regarding the magnitude gap, the separation can be done at {Delta}m_12_=1.0. The central galaxy paradigm (CGP) may not be valid for ~20 per cent of relaxed massive clusters. This fraction increases to ~60 per cent for disturbed systems.
