Non-thermal motions in the intra-cluster medium (ICM) are believed to play a non-negligible role in the pressure support to the total gravitating mass of galaxy clusters. Future high-precision X-ray missions will allow us to directly detect the signature of these motions from highly resolved spectra of the ICM. With this perspective, we will present here a study on a set of clusters extracted from a cosmological hydrodynamical simulation, for which we simulated X-ray observations and characterized them via the non-thermal velocity amplitude of the ICM. We have applied the X-ray virtual telescope PHOX to generate mock observations of the simulated clusters and estimated in an observational fashion global X-ray properties. We included ICM non-thermal motions as additional parameter to further identify non-regular clusters. In particular, the influence of internal gas motions on the location of clusters in the LX-T plane was investigated and was found that objects with the largest amount of non-thermal velocity have on average higher X-ray luminosities. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The hierarchical formation of clusters of galaxies by accretion of material releases gravitational energy which dissipates into the intracluster gas. The process heats the material and generates gas turbulence and bulk motions and thus kinetic pressure. Mapping the velocity fields of the moving subunits would enable a new diagnostics tool for cluster formation studies and unbiased X-ray mass estimates. The required spatially resolved high resolution spectroscopy is not currently available. I demonstrate here the feasibility of detecting and mapping the velocities of the bulk motions using the Doppler shift of the Fe XXV Kα line with the proposed ATHENA satellite. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We report on recent Suzaku results on cluster outer regions. Relaxed clusters show a monotonous temperature decline to the virial radii, reaching 1/3 to 1/4 of the central levels. Significant temperature jumps have been confirmed for a number of radio relics, including A 3667, A 3376, and CIZA J2242.8+5301. This confirms that the radio relics generally correspond to shock fronts with the Mach numbers around 3. New filament junctions are identified by a new algorithm applied to the SDSS galaxy distribution and show significant X-ray emission with Suzaku. The emission agrees with the L_X-kT relation for elliptical galaxies and galaxy groups, and the junctions can be a important baryon reservoir. We propose a small X-ray mission DIOS (Diffuse Intergalactic Oxygen Surveyor), equipped with microcalorimeters with a wide field of view (∼50′), which will detect the emission from warm-hot intergalactic medium (WHIM) and measure detailed thermal and dynamical properties of the gas accreting onto clusters from the filaments. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We have undertaken the DAFT/FADA survey with the double aim of setting constraints on dark energy based on weak lensing tomography and of obtaining homogeneous and high quality data for a sample of 91 massive clusters in the redshift range 0.4–0.9 for which there were HST archive data. We have analysed the XMM-Newton data available for 42 of these clusters to derive their X-ray temperatures and luminosities and search for substructures. Out of these, a spatial analysis was possible for 30 clusters, but only 23 had deep enough X-ray data for a really robust analysis. This study was coupled with a dynamical analysis for the 26 clusters having at least 30 spectroscopic galaxy redshifts in the cluster range. Altogether, the X-ray sample of 23 clusters and the optical sample of 26 clusters have 14 clusters in common. We present preliminary results on the coupled X-ray and dynamical analyses of these 14 clusters. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

LOFAR, the Low Frequency Radio Array, is a new pan-European radio telescope that is almost fully operational. One of its main drivers is to make deep images of the low frequency radio sky. To be able to do this a number of challenges need to be addressed. These include the high data rates, removal of radio frequency interference, calibration of the beams and correcting for the corrupting influence of the ionosphere. One of the key science goals is to study merger shocks, particle acceleration mechanisms and the structure of magnetic fields in nearby and distant merging clusters. Recent studies with the GMRT and WSRT radio telescopes of the “Sausage” and the “Toothbrush” clusters have given a very good demonstration of the power of radio observations to study merging clusters. Recently we discovered that both clusters contain relic and halo sources, large diffuse regions of radio emission not associated with individual galaxies. The 2 Mpc northern relic in the Sausage cluster displays highly aligned magnetic fields and and exhibits a strong spectral index gradient that is a consequence of cooling of the synchrotron emitting particles in the post-shock region. We have argued that these observations provide strong evidence that shocks in merging clusters are capable of accelerating particles. For the Toothbrush cluster we observe a puzzling linear relic that extends over 2 Mpc. The proposed scenario is that a triplemerger can lead to such a structure. With LOFAR's sensitivity it will not only be possible to trace much weaker shocks, but also to study those shocks due to merging clusters up to redshifts of at least one. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Recently, a number of new galaxy clusters have been detected by the ESA-Planck satellite, the South Pole Telescope, and the Atacama Cosmology Telescope using the Sunyaev-Zel'dovich effect. Several of the newly detected clusters are massive, merging systems with disturbed morphology in the X-ray surface brightness. Diffuse radio sources in clusters, called giant radio halos and relics, are direct probes of cosmic rays and magnetic fields in the intra-cluster medium. These radio sources are found to occur mainly in massive merging clusters. Thus, the new SZ-discovered clusters are good candidates to search for new radio halos and relics. We have initiated radio observations of the clusters detected by Planck with the Giant Metrewave Radio Telescope. These observations have already led to the detection of a radio halo in PLCKG171.9–40.7, the first giant halo discovered in one of the new Planck clusters. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Multiwavelength studies of radio relics at merger shocks set powerful constraints on the relics origin and formation mech-anism. However, for X-ray observations, a main difficulty is represented by the low X-ray surface brightness far out in the cluster outskirts, where relics are typically found. Here, we present XMM-Newton results from a 130-ks observation of CIZA J2242.8+5301, a cluster at z = 0.19 that hosts a double radio relic. We focus on the well-defined northern relic. There is a difference of ∼55% between the temperature we measure behind the relic, and the temperature measured with Suzaku. We analyse the reasons for this large discrepancy, and discuss the possibility of reliably measuring the temperature beyond the northern relic. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We present new XMM-Newton observations of the northwest (NW) radio relic region in the cluster Abell 3667. We detect a jump in the X-ray surface brightness and X-ray temperature at the sharp outer edge of the radio relic which indicate that this is the location of a merger shock with a Mach number of about 2. Comparing the radio emission to the shock properties implies that approximately 0.2% of the dissipated shock kinetic energy goes into accelerating relativistic electrons. This is an order of magnitude smaller than the efficiency of shock acceleration in many Galactic supernova remnants, which may be due to the lower Mach numbers of cluster merger shocks. The X-ray and radio properties indicate that the magnetic field strength in the radio relic is ≳ 3 µG, which is a very large field at a projected distance of ∼ 2.2 Mpc from the center of a cluster. The radio spectrum is relatively flat at the shock, and steepens dramatically with distance behind the shock. This is consistent with radiative losses by the electrons and the post-shock speed determined from the X-ray properties. The Cygnus A radio source is located in a merging cluster of galaxies. This appears to be an early-stage merger. Our recent Suzaku observation confirm the presence of a hot region between the two subclusters which agrees with the predicted shocked region. The high spectral resolution of the CCDs on Suzaku allowed us to measure the radial component of the merger velocity, Δv_r ≈ 2650 km s^–1. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We present correlation results for the radio halo power in galaxy clusters with the integrated thermal Sunyaev-Zel'dovich (SZ) effect signal, including new results obtained at sub-GHz frequencies. The radio data is compiled from several published works, and the SZ measurements are taken from the Planck ESZ cluster catalog. The tight correlation between the radio halo power and the SZ effect demonstrates a clear correspondence between the thermal and non-thermal electron populations in the intra-cluster medium, as already have been shown in X-ray based studies. The radio power varies roughly as the square of the global SZ signal, but when the SZ signal is scaled to within the radio halo radius the correlation becomes approximately linear, with reduced intrinsic scatter. We do not find any strong indication of a bi-modal division in the radio halo cluster population, as has been reported in the literature, which suggests that such duality could be an artifact of X-ray selection. We compare the Y_SZ dependence of radio halos with simplified predictions from theoretical models, and discuss some implications and shortcomings of the present work. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The distribution of the gravitating and baryonic mass in galaxy clusters is the key ingredient to use these structures as astro-physical laboratories and cosmological probes. I review the methods used to recover the gas and total mass profiles for galaxy clusters from X-ray observations. I discuss some of the limitations affecting the X-ray analysis. I illustrate how the estimates of the gas mass fraction and of the mass concentration can be used as robust cosmological tools. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We discuss a simple and robust procedure to evaluate the mass/circular velocity of massive elliptical galaxies and clusters of galaxies. It relies only on the surface density and the projected velocity dispersion profiles of tracer particles and therefore can be applied even in case of poor or noisy observational data. Stars, globular clusters or planetary nebulae can be used as tracers for mass determination of elliptical galaxies. For clusters the galaxies themselves can be used as tracer particles. The key element of the proposed procedure is the selection of a “sweet” radius R_sweet, where the sensitivity to the unknown anisotropy of the tracers' orbits is minimal. At this radius the surface density of tracers declines approximately as I(R) α R^–2, thus placing R_sweet not far from the half-light radius of the tracers R_eff. The procedure was tested on a sample of cosmological simulations of individual galaxies and galaxy clusters and then applied to real observational data. Independently the total mass profile was derived from the hydrostatic equilibrium equation for the gaseous atmosphere. Mismatch in mass profiles obtained from optical and X-ray data is used to estimate the non-thermal contribution to the gas pressure and/or to constrain the distribution of tracers' orbits. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this paper we discuss various methods for clustering in order to determine estimates of the cluster mass, focusing on the cluster A3581. Using virtual observatory (VO) tools, possible galaxy cluster candidates are selected. Using the Kayes Mixture Model (KMM) algorithm and the Gaussian Mixing Model (GMM), we determine the most likely cluster member candidates. We then compare the results obtained to SIMBADs method of hierarchy. The mass of A 3581 was calculated and checked with literature values. We discuss the sensitivity of the mass determination and show that the GMM provides a very robust method to determine member candidates for cluster A 3581. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Galaxy clusters are an attractive tool to constrain cosmological parameters and well-determined scaling relations between X-ray observables and cluster mass give us a precious diagnostic to study the thermodynamical history of the intra-cluster medium (ICM). We are in the process of improving the accuracy of scaling relations using a complete sample of galaxy groups to study if there is a systematic difference between clusters and groups and the influence of non-gravitational physics on low-mass systems. By combining this sample with the HIFLUGCS sample creates a master sample of 86 groups and clusters ranging over more than three orders of magnitude in luminosity. This large leverage will directly allow us to place tight constraints on cosmological parameters. We present here the results of an ongoing work in which we analyze a complete sample of galaxy groups from observations taken with XMM. The results are compared with the ones obtained using the HIFLUGCS sample. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We have analyzed the growth curves and the surface brightness light profiles of the clusters of the WINGS sample (Fasano et al. 2006) in the B and V bands, measuring the effective radii, the effective surface brightnesses and the total luminosities of our clusters. The similarly of the radial surface brightness profiles of early-type galaxies (ETGs) and clusters indicate that within r200 almost all clusters are virialized structures. The total luminosities L_B of clusters are found to correlate with the X-ray luminosity L_X, following approximately the same relation measured for galaxies by Eskridge et al. (1995). By coupling the photometric data with the central velocity dispersions, derived from the radial velocities of the galaxies measured by Cava et al. (2009), we were able to fit the fundamental plane (FP) of clusters of galaxies. We find that it has approximately the same slope of the FPs of early-type galaxies (ETGs) and globular clusters (GCs), but differs from them in the zero-point. This behavior can be easily explained in terms of a different contribution of dark matter (DM). (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We present the XMM-Newton X-ray analysis of RX J1720.1+2638 and Abell 267, a non-fossil and a fossil system, respectively. The whole spectrum of both objects can be explained by thermal emission. The luminosities found for RX J1720.1+2638 and Abell 267 in the 2–10 keV band are 6.20^+0.04 _–0.02 × 1044 and 3.90^+0.10 _–0.11 ×10⁴⁴ erg s^–1, respectively. The radial profiles show a cool core nature for the non-fossil system RX J1720.1+2638, while Abell 267 shows a constant behaviour of temperature with radius. Metallicity profiles have also been produced, but no evidence of any gradient was detected due to the large uncertainties in the determination of this parameter. Finally, density and mass profiles were also produced allowing to derive M₅₀₀ for RX J1720.1+2638 and Abell 267. The masses obtained are high, in the range of (5–7)× 10¹⁴ M_⊙. The X-ray properties obtained for both systems are not always in good agreement with what is expected: cool cores are expected for fossil systems, as Abell 267, considering them as and relaxed systems. However, the decrement of the temperature in Abell 267 could start at lower radii. Also the presence of a recent merger in Abell 267, already suggested in the literature, could have increased the central temperature. The non-fossil system RX J1720.1+2638 actually exhibits a cool core profile, but also evidence of a recent merger has been reported. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Clusters of galaxies provide a rich variety of phenomena in the far-infrared and the Herschel Space Observatory has performed a number of comprehensive imaging and spectroscopic observations of clusters over a wide redshift range. This talk gives an overview of the results available to date and the prospects for the observations yet to come. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Observations support the view that feedback, in the form of radio outbursts from active nuclei in central galaxies, prevents catastro-phic cooling of gas and rapid star formation in many groups and clusters of galaxies. Variations in jet power drive a succession of weak shocks that can heat regions close to the active galactic nuclei (AGN). On larger scales, shocks fade into sound waves. The Braginskii viscosity determines a well-defined sound damping rate in the weakly magnetised intracluster medium (ICM) that can provide sufficient heating on larger scales. It is argued that weak shocks and sound dissipation are the main means by which radio AGN heat the ICM, in which case, the power spectrum of AGN outbursts plays a central role in AGN feedback. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The Chandra X-ray Observatory has revealed X-ray bubbles in the intracluster medium (ICM) of many nearby clusters, which are thought to be created by the central active galactic nucleus (AGN). However, the duty cycle of such AGN outbursts is not well understood. In order to further understand how cooling is balanced by bubble heating we studied complete samples of cooling flow clusters (from the Brightest 55 clusters of galaxies sample, B55, and the HIghest X-ray FLUx Galaxy Cluster Sample, HIFLUGCS). We found that there is a radio luminosity cut-off of 2.5×10³⁰ erg s^–1 Hz^–1 for the cooling flow clusters. Furthermore, we find a duty cycle for radio mode feedback, the fraction of time that a system possesses bubbles inflated by its central radio source, of ≳ 69 % for the B55 sample and ≳ 63 % for the HIFLUGCS sample. These duty cycles are lower limits since some bubbles are likely missed in existing images. We used simulations to constrain the bubble power that might be present and remain undetected in the cooling flow systems without detected bubbles. Among theses systems, almost all could have significant bubble power. Therefore, our results imply that the duty cycle of AGN outbursts with the potential to heat the gas significantly in cooling flow clusters is at least 60% and could approach 100 %. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Unopposed radiative cooling of plasma would lead to the cooling catastro-phe, a massive inflow of condensing gas, manifest in the core of galaxies, groups and clusters. The last generation X-ray telescopes, Chandra and XMM, have radically changed our view on baryons, indicating AGN heating as the balancing counterpart of cooling. This work reviews our extensive investigation on self-regulated heating. We argue that the mechanical feedback, based on massive subrelativistic outflows, is the key to solving the cooling flow problem, i.e. dramatically quenching the cooling rates for several Gyr without destroying the cool-core structure. Using a modified version of the 3D hydrocode FLASH, we show that bipolar AGN outflows can further reproduce fundamental observed features, such as buoyant bubbles, weak shocks, metals dredgeup, and turbulence. The latter is an essential ingredient to drive nonlinear thermal instabilities, which cause the formation of extended cold gas, a residual of the quenched cooling flow and, later, fuel for the feedback engine. Compared to clusters, groups and galaxies require a gentler mechanical feedback, in order to avoid catastro-phic overheating. We highlight the essential characteristics for a realistic AGN feedback, with emphasis on observational consistency. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In this paper, a new set of 30 high resolution cosmological simulations of galaxy clusters, run with increasingly realistic physics, are presented and compared to observations of the Sunyaev-Zel'dovich (SZ) effect. It is found that the best fit to the Y₅₀₀-M₅₀₀ relation is from the model without gas cooling, and that supernova feedback is insufficient to counteract the effect of cooling on the gas pressure. Clearly another more powerful source of feedback is required, suggesting that including the effects of active galactic nuclei (AGN) is vital if we are to replicate the SZ properties of the clusters accurately. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We study the similarities of jet-medium interactions in several quite different astro-physical systems using 2D and 3D hydrodynamical numerical simulations, and find many similarities. The systems include cooling flow (CF) clusters of galaxies, core collapse supernovae (CCSNe), planetary nebulae (PNe), and common envelope (CE) evolution. The similarities include hot bubbles inflated by jets in a bipolar structure, vortices on the sides of the jets, vortices inside the inflated bubbles, fragmentation of bubbles to two and more bubbles, and buoyancy of bubbles. The activity in many cases is regulated by a negative feedback mechanism. In CF clusters we find that heating of the intra-cluster medium (ICM) is done by mixing hot shocked jet gas with the ICM, and not by shocks. Our results strengthen the jet feedback mechanism (JFM) as a common process in many astro-physical objects. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Radio galaxies are among the largest and most powerful single objects known and are found at variety of redshifts, hence they are believed to have had a significant impact on the evolving Universe. Their relativistic jets inject considerable amounts of energy into the environments in which the sources reside; thus the knowledge of the fundamental properties (such as kinetic luminosities, lifetimes and ambient gas densities) of these sources is crucial for understanding AGN feedback in galaxy clusters. In this work, we explore the intrinsic and extrinsic fundamental properties of Fanaroff-Riley II (FR II) objects through the construction of multidimensional Monte Carlo simulations which use complete, flux limited radio catalogues and semi-analytical models of FR IIs' time evolution to create artificial samples of radio galaxies. This method allows us to set better limits on the confidence intervals of the intrinsic and extrinsic fundamental parameters and to investigate the total energy produced and injected to the clusters' environments by populations of FR IIs at various cosmological epochs (0.0 < z < 2.0). We find the latter estimates to be strikingly robust despite the strong degeneracy between the fundamental parameters – such a result points to a conclusive indicator of the scale of AGN feedback in clusters of galaxies. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We analyzed the spectra collected under the wide-field nearby galaxy clusters survey (WINGS) to reveal emission lines in cluster galaxies. After removing stellar emission with dedicated population synthesis models we found evidence of faint emission line activity in a sizable number of sources. Diagnostic diagrams were used to define or at least constrain the origin of the emission line activity. Cross-correlation with radio surveys is also being used for the identification of “true” active nuclei. We report the discovery of a previously unknown Seyfert 1 nucleus, WINGS J230945.81+072431.0, and preliminary results on prevalence and basic properties of the active and star forming galaxies we identified. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Metals play a fundamental role in ICM cooling processes in cluster cores through the emission of spectral lines. But when and how were these metals formed and distributed through the ICM? The X-ray band has the unique property of containing emission lines from all elements from carbon to zinc within the 0.1–10 keV band. Using XMM-Newton, the abundances of about 11 elements are studied, which contain valuable information about their origin. Most elements were formed in type Ia and core-collapse supernovae, which have very different chemical yields. Massive stars and AGB stars also contribute by providing most of the carbon and nitrogen in the ICM. Because feedback processes suppress star formation in the cluster centre, the element abundances allow us to directly probe the star formation history of the majority of stars that are thought to have formed between z = 2–3. The spatial distribution in the core and the evolution with redshift also provide information about how these elements are transported from the member galaxies to the ICM. I review the current progress in chemical enrichment studies of the ICM and give an outlook to the future opportunities provided by XMM-Newton's successors, like Astro-H. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Cold-fronts in cool-core clusters are thought to be induced by minor mergers and to develop through a sloshing mechanism. While temperature and surface-brightness jumps have been detected and measured in many systems, a detailed characterization of the metal abundance across the discontinuity is only available for a handful of objects. Within the sloshing scenario, we expect the central cool and metal rich gas to be displaced outwards into lower abundance regions, thus generating a metal discontinuity across the front. We analyzed a long (120 ks) XMM-Newton observation of A496 to study the metal distribution and its correlation with the cold-fronts. We find Fe discontinuities across the two main cold-fronts located ∼ 60 kpc NNW and ∼ 160 kpc south of the peak and a metal excess in the south direction. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We report on the abundance of metals (Mg and Fe) in the intracluster medium (ICM) at the outskirts (0.2 r₂₀₀–0.8 r₂₀₀) of the Perseus cluster. The X-ray spectra were obtained in the Suzaku/XIS mapping observations of this region. We employ single temperature models to fit all the X-ray spectra. The ICM temperature smoothly decreases toward the outer region from 6 keV to 4 keV. The Fe abundance is uniformly distributed at the outskirts (∼0.3 solar). The Mg abundance is ∼ 1 solar at the outskirts. The solar ratios of Mg/Fe of the outskirts region (Mg/Fe ∼ 4) are a factor of 4 larger than those of the central region. Various systematic effects, including the spatial fluctuations in the cosmic X-ray background, are taken into account and evaluated. Our results have not changed significantly. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The Planck satellite has surveyed the whole sky more than four times. The nominal mission of two all-sky surveys will be released to the public in 2013. From the first all-sky survey, we have demonstrated the ability to detect clusters via the Sunyaev-Zel'dovich effect with high reliability and out to large redshifts. We have released the first large sample of 189 high signal-to-noise SZ clusters. We also presented the detection of 45 new Planck clusters, confirmed in X-ray with the XMM-Newton satellite. The Planck collaboration is engaged in a massive identification and follow-up programme of its SZ sources at X-ray, optical, and SZ wavelengths. Dedicated cluster studies are also conducted by the consortium in order to better constrain the scaling and structural properties of the cluster population. We have thus provided high precision calibration of scaling relation between the SZ signal and the clusters physical quantities. The excellent agreement found between SZ and X-ray measurements have demonstrated our good understanding of the hot intra-cluster gas at least within R500. These results together with those from other operating SZ instruments are shading new light on our understanding of the most massive bound structure of the Universe. With its whole sky reach and unprecedented frequency coverage, the Planck mission is a crucial asset to these endeavours. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Clusters of galaxies were first recognized through overdensities of galaxies. With the advent of X-ray telescopes, large numbers of clusters were by found by the spatially extended nature of their X-ray emission. Today with the availability of millimeter wave telescopes capable of finding clusters through the Sunyaev-Zeldovich effect, it is possible to compare the overall characteristics of clusters detected by different methods and the specific properties of individual clusters measured in different ways. Here we compare the X-ray properties of relatively low redshift clusters measured with the Chandra Observatory with their SZ signal measured in the Planck mission. Based on a sample of 114 Planck detected clusters of galaxies, we show the SZ signal strengths are strongly correlated with X-ray measured mass proxies, in particular those measured through the cluster X-ray luminosities, so long as the cluster core is excluded, and those measured from Y_X, the product of the gas temperature and gas mass, which is an X-ray analog of the SZ signal Y_SZ. A comparison of the hundred brightest X-ray clusters and the hundred Planck clusters with the highest SZ signals shows that the Planck ESZ cluster sample is more X-ray luminous and more massive than X-ray cluster sample, due in part to the larger volume that Planck clusters are detected over, due to the nearly redshift independence of the SZ strength. As previously found, on average the SZ cluster samples show a larger fraction of clusters undergoing mergers than do X-ray selected samples. For the Planck ESZ cluster PLCKESZ G189.84–37.24, we report the detection of extended X-ray emission associated with an overdensity of distant galaxies located 6′.5 from the Planck ESZ position. Future X-ray observations of the Planck low redshift (z < 0.35) cluster sample will better define the low redshift cluster mass function for comparison to high redshift SZ selected cluster samples to better constrain cosmological parameters, particularly the equation of state for dark energy. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

This work describes the baryon content and Sunyaev-Zeldovich properties of the MUSIC (Marenostrum-MultiDark SIm-ulations of galaxy clusters) dataset and their evolution with redshift and aperture radius. The MUSIC dataset is one of the largest samples of hydrodynamically simulated galaxy clusters (more than 2000 objects, including more than 500 clusters). We show that when the effects of cooling and stellar feedbacks are properly taken into account, the gas fraction of the MUSIC clusters consistently agrees with recent observational results. Moreover, the gas fraction has a net dependence with the total mass of the cluster and increases slightly with redshift at high overdensities.

The study of the Y –M relation confirms the consistence of the self-similar model, showing no evolution with redshift at low overdensities. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The accurate determination of the mass of galaxy clusters is crucial to precision astronomy. We have often to deal with either biased measurements or precise determinations of peculiar quantities. A better understanding of intrinsic shapes plays a major role. We consider how the shape of the intracluster medium (ICM) can be inferred by combining X-ray photometry and spectroscopy with the measurement of the Sunyaev-Zel'dovich effect (SZe). Together with gravitational lensing (GL), we can get unbiased estimates of mass and concentration and probe the hydrodynamical properties of the cluster. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

With its unprecedented ability to scrutinise the sub-millimetre (sub-mm) to centimetre full sky, the Planck satellite is uniquely suited to search for the progenitors of clusters of galaxies. The forming massive halos at z ≳1–2 are expected to host massive galaxies with high star formation rates. Clustered in the growing potential well that is being established, these galaxies are within Planck 's reach via their sub-mm emission. We have applied a new colour-based method combining Planck and IRAS data to detect the rarest and brightest sub-mm cold sources on the sky. In this work, we describe the method and present the first confirmations of our high-z candidates, particularly focusing on 17p732, a newly discovered high-z (proto)cluster candidate at z ⋍ 1.7 for which we carried a multi-wavelength follow-up. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Based on optical and X-ray data for a sample of 34 relaxed rich clusters with redshift of 0.1–0.9, we studied the relative spatial distribution of the two major baryon contents, the cluster galaxies and the hot plasmas. Using photometric data taken with the UH88 telescope, we determined the integrated radial light profiles of member galaxies in each cluster using two independent approaches, i.e., the field background subtraction and the color-magnitude filtering. The ICM mass profile of each cluster in our sample was derived from a spatially-resolved spectral analysis using XMM-Newton and Chandra data. When the sample is divided into three subsamples with redshift intervals of z = 0.11–0.22, 0.22–0.45, and 0.45– 0.89, the galaxy light vs. ICM mass ratio profiles for the central 0.65R₅₀₀ regions were found to steepen from the higher- to lower- redshift subsamples, meaning that the galaxies become more concentrated in the ICM sphere towards lower redshifts. Besides, the galaxy light vs. total mass ratio profiles also exhibit gradual concentration towards lower redshift. We interpret that the galaxies, the ICM, and the dark matter components followed a similar spatial distribution in the early phase (z > 0.5), while the galaxies have fallen towards the center relative to the ICM and dark matter. Such galaxy infall is likely tobe caused by ICM drag when galaxies move through the ICM, even though the dynamical friction can enhance the infall of the most massive galaxies. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The GaLAxy Cluster Evolution survey (GLACE) is aimed to study the evolution of emission line galaxies in clusters across the cosmic time. It takes advantage of the tunable filter mode of OSIRIS (first light instrument of GTC) to scan Hα /[N II], Hβ, [O II]3727 and [O III]5007 searching for star formation activity and AGNs in clusters in three different redshift windows (z ∼ 0.40, 0.63, and 0.86), providing a unique view of the evolution of cluster galaxies along such redshift range. Moreover, the OSIRIS large field of view (8×8 arcmin²) together with GTC large collective area (D ∼ 10 m) make it possible to detect SFR ∼ 2 M_⊙ yr^–1 in an angular area up to 2R_vir. We present here the first results of the program together with a brief description of this novel technique focusing in the cluster CL0024+1654 (z ∼ 0.39). (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The XMM Cluster Survey (XCS) is a serendipitous search for galaxy clusters using all publicly available data in the XMM-Newton Science Archive. Our recent first data release (XCS-DR1) contains 503 optically confirmed groups and clusters, among which 256 new to the literature and 357 whose X-ray emission was detected for the first time. We discuss their properties and provide an update on the work being done. As examples of the applications of XCS-DR1, we mention the 17 fossil groups/clusters identified with the help of the Sloan Digital Sky Survey. Their brightest galaxies have stellar populations and star-formation histories which are similar to normal brightest cluster galaxies, but their stellar masses are significantly larger and correspond to a much bigger fraction of the total group/cluster optical luminosity. We also highlight the 15 clusters expected tobe also detected by the Planck satellite, and characterize the expected overlap between the final XCS and Planck cluster catalogues. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The stellar mass and metallicity are among the fundamental parameters of galaxies. An understanding of the interplay between those properties as well as their environmental dependence will give us a general picture of the physics and feedback processes ongoing in groups of galaxies. We study the relationships and environmental dependencies between the stellar mass, and gas metallicity for more than 1900 galaxies in groups up to redshift 0.35 using the Galaxy And Mass Assembly (GAMA) survey. Using a control sample of more than 28000 star-forming field galaxies, we find evidence for a decrement of the gas metallicity for galaxies in groups. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The XMM-Newton Distant Cluster Project (XDCP) aims at the identification of a well defined sample of X-ray selected clusters of galaxies at redshifts z ≥ 0.8. As part of this project, we analyse the deep archival XMM-Newton exposure of LBQS 2212–1759 to quantify the cluster content. We validate the optical follow-up strategy as well as the X-ray selection function. We base the cluster identification of the extended X-ray sources on deep imaging with the ESO-VLT and on the CFHT-LS. The confirmation of cluster candidates is done by VLT/FORS2 spectroscopy. Photometric redshifts from CFTH-LS D4 are utilised to confirm the effectiveness of the X-ray cluster selection method. The survey sensitivity is computed to have a flux limit of S_{0.5–2.0 keV} ∼ 2.5×10^–15 erg s^–1 for 50% completeness in an area ∼0.13 deg². We detect six clusters of galaxies above this level both in X-rays and the optical. Two newly discovered X-ray luminous clusters of galaxies in this work are at z ≥ 1.0 and one is at z = 0.41. The constructed log N -log S tends to favour a scenario where no evolution in the cluster X-ray luminosity function takes place. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Our searches in the CLASH data have found many high-redshift galaxy candidates. One object at z = 6.2 in MACS J0329-02 is quadruply lensed. Another object in MACS J1149+22 is at redshift z = 9.6 and AB = 25.7, the first candidate at z > 9 that is bright enough for spectroscopic observations. The discovery of more than 80 galaxy candidates at z > 7 demonstrates the unique potential of galaxy cluster fields for finding highly magnified, intrinsically faint galaxies at the highest redshifts. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Galaxy clusters are one of the important cosmological probes to test the consistency of the observable structure and evolution of our Universe with the predictions of specific cosmological models. We use results from our analysis of the X-ray flux-limited REFLEX cluster sample from the ROSAT All-Sky Survey to illustrate the constraints on cosmological parameters that can be achieved with this approach. The upcoming eROSITA project of the Spektrum-Roentgen-Gamma mission will increase these capabilities by two orders of magnitude and importantly also increase the redshift range of such studies. We use the projected instrument performance to make predictions on the scope of the eROSITA survey and the potential of its exploitation. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The field of research on galaxy clusters has received an enormous increase in attention in the last years, since galaxy clusters have been more and more recognized as very important laboratories for astro-physical studies and observational probes for testing cosmological models. X-ray observations of these largest clearly defined objects in our Universe have been by far the most fruitful approach that has provided us with rich astro-physical and cosmological insights. ESA's XMM-Newton and NASA's Chandra observatories have been the powerhorses of this research. In this article we therefore like to summarize the major advances made in the field of galaxy cluster research primarily by these two instruments. We will touch the progress in understanding the structure of galaxy clusters and its statistics, the AGN feedback processes in the center of clusters, cosmic evolution of clusters, cluster mass measurements, the thermodynamic structure of the intracluster medium and its chemistry, X-ray surveys of clusters, and the use of galaxy clusters for cosmological tests. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)