X-ray Properties Of Clusters Research Articles

The galaxy clusterYSZ−LXandYSZ−Mrelations from the WMAP 5-yr data

We use multifrequency matched filters to estimate, in the WMAP 5-year data, the Sunyaev-Zel'dovich (SZ) fluxes of 893 ROSAT NORAS/REFLEX clusters spanning the luminosity range Lx,[0.1-2.4]keV = 2 10^{41} - 3.5 10^{45} erg s^{-1}. The filters are spatially optimised by using the universal pressure profile recently obtained from combining XMM-Newton observations of the REXCESS sample and numerical simulations. Although the clusters are individually only marginally detected, we are able to firmly measure the SZ signal (>10 sigma) when averaging the data in luminosity/mass bins. The comparison between the bin-averaged SZ signal versus luminosity and X-ray model predictions shows excellent agreement, implying that there is no deficit in SZ signal strength relative to expectations from the X-ray properties of clusters. Using the individual cluster SZ flux measurements, we directly constrain the Y500-Lx and Y500-M500 relations, where Y500 is the Compton y-parameter integrated over a sphere of radius r500. The Y500-M500 relation, derived for the first time in such a wide mass range, has a normalisation Y*500=[1.60 pm 0.19] 10^{-3} arcmin^2 at M500=3 10^{14} h^{1} Msun, in excellent agreement with the X-ray prediction of 1.54 10^{-3} arcmin^2, and a mass exponent of alpha=1.79 pm 0.17, consistent with the self-similar expectation of 5/3. Constraints on the redshift exponent are weak due to the limited redshift range of the sample, although they are compatible with self-similar evolution.

Parsec-scale properties of brightest cluster galaxies

We present new VLBI observations at 5 GHz of a complete sample of brightest cluster galaxies (BCGs) in nearby Abell clusters (distance class <3). Combined with data from the literature, we provide parsec-scale information for 34 BCGs. Our analysis of the parsec-scale radio emission of BCGs and the cluster X-ray properties finds a possible dichotomy between BCGs in cool-core clusters and those in non-cool-core clusters. Among resolved sources, those in cool-core clusters tend to have two-sided parsec-scale jets, while those in less relaxed clusters have predominantly one-sided parsec-scale jets. We suggest that this difference is caused by the interplay between the jets and the surrounding medium. The one-sided structure in non-cool-core clusters may be due to Doppler boosting effects in relativistic, intrinsically symmetric jets whereas two-sided morphology in cool core clusters is probably related to the presence of heavy and mildly relativistic jets that have been decelerated on the parsec-scale. Evidence of recurrent activity is also found in BCGs in cool-core clusters.

X-ray groups and clusters of galaxies in the Subaru-XMM Deep Field

We present the results of a search for galaxy clusters in Subaru-XMM Deep Field. We reach a depth for a total cluster flux in the 0.5-2 keV band of 2x10^{-15} ergs cm^{-2} s^{-1} over one of the widest XMM-Newton contiguous raster surveys, covering an area of 1.3 square degrees. Cluster candidates are identified through a wavelet detection of extended X-ray emission. The red sequence technique allows us to identify 57 cluster candidates. We report on the progress with the cluster spectroscopic follow-up and derive their properties based on the X-ray luminosity and cluster scaling relations. In addition, 3 sources are identified as X-ray counterparts of radio lobes, and in 3 further sources, X-ray counterpart of radio lobes provides a significant fraction of the total flux of the source. In the area covered by NIR data, our identification success rate achieves 86%. We detect a number of radio galaxies within our groups and for a luminosity-limited sample of radio galaxies we compute halo occupation statistics using a marked cluster mass function. We compare the cluster detection statistics in the SXDF with the predictions of concordance cosmology and current knowledge of the X-ray cluster properties, concluding that a reduction of concordance sigma_8 value by 5% is required in order to match the prediction of the model and the data. This conclusion still needs verification through the completion of cluster follow-up.

Intra cluster medium properties and AGN distribution in high-zRCS clusters

Context. The study of the thermodynamical and chemical properties of the intra cluster medium (ICM) in high redshift clusters of galaxies is a powerful tool for investigating the formation and evolution of large scale structures. Here we discuss the X-ray properties of clusters of galaxies optically selected in the red-sequence cluster survey (RCS) observed with the Chandra satellite, at redshifts 0.6 1. Finally, we find the significant excess of medium and low luminosity AGN close to the centroid of the X-ray emission. Their X-ray emission is not dominating the ICM, but their presence may be relevant for studying the interaction between AGN and ICM.

TheXMMCluster Survey: The Dynamical State of XMMXCS J2215.9−1738 atz= 1.457

We present new spectroscopic observations of the most distant X-ray selected galaxy cluster currently known, XMMXCS J2215.9-1738 at z=1.457, obtained with the DEIMOS instrument at the W. M. Keck Observatory, and the FORS2 instrument on the ESO Very Large Telescope. Within the cluster virial radius, as estimated from the cluster X-ray properties, we increase the number of known spectroscopic cluster members to 17 objects, and calculate the line of sight velocity dispersion of the cluster to be 580+/-140 km/s. We find mild evidence that the velocity distribution of galaxies within the virial radius deviates from a single Gaussian. We show that the properties of J2215.9-1738 are inconsistent with self-similar evolution of local X-ray scaling relations, finding that the cluster is underluminous given its X-ray temperature, and that the intracluster medium contains ~2-3 times the kinetic energy per unit mass of the cluster galaxies. These results can perhaps be explained if the cluster is observed in the aftermath of an off-axis merger. Alternatively, heating of the intracluster medium through supernovae and/or Active Galactic Nuclei activity, as is required to explain the observed slope of the local X-ray luminosity-temperature relation, may be responsible.

A comparison of weak-lensing masses and X-ray properties of galaxy clusters

We present measurements of the masses of 20 X-ray luminous clusters of galaxies at intermediate redshifts, determined from a weak-lensing analysis of deep archival R-band data obtained using the Canada-France-Hawaii Telescope. Compared to previous work, our analysis accounts for a number of effects that are typically ignored, but can lead to small biases, or incorrect error estimates. We derive masses that are essentially model-independent and find that they agree well with measurements of the velocity dispersion of cluster galaxies and with the results of X-ray studies. Assuming a power law between the lensing mass and the X-ray temperature, M 2500 oc T α , we find a best-fitting slope of a = 1.34 +0.30 -0.28 . This slope agrees with self-similar cluster models and studies based on X-ray data alone. For a cluster with a temperature of kT = 5 keV we obtain a mass M 2500 = (1.4 ± 0.2) x 10 14 h -1 M⊙ in fair agreement with recent Chandra and XMM studies.

X‐Ray Galaxy Clusters in NoSOCS: Substructure and the Correlation of Optical and X‐Ray Properties

We present a comparison of optical and X-ray properties of galaxy clusters in the northern sky. We determine the recovery rate of X-ray detected clusters in the optical as a function of richness, redshift and X-ray luminosity, showing that the missed clusters are typically low contrast systems when observed optically. We employ four different statistical tests to test for the presence of substructure using optical two-dimensional data, finding that approximately 35% of the clusters show strong signs of substructure. However, the results are test-dependent, with variations also due to the magnitude range and radius utilized.We have also performed a comparison of X-ray luminosity and temperature with optical galaxy counts (richness). We find that the slope and scatter of the relations between richness and the X-ray properties are heavily dependent on the density contrast of the clusters. The selection of substructure-free systems does not improve the correlation between X-ray luminosity and richness, but this comparison also shows much larger scatter than one obtained using the X-ray temperature. In the latter case, the sample is significantly reduced because temperature measurements are available only for the most massive (and thus high contrast) systems. However, the comparison between temperature and richness is very sensitive to the exclusion of clusters showing signs of substructure. The correlation of X-ray luminosity and richness is based on the largest sample to date ($\sim$ 750 clusters), while tests involving temperature use a similar number of objects as previous works ($\lsim$100). The results presented here are in good agreement with existing literature.

Strange magnification pattern in the large separation lens SDSS J1004+4112 from optical to X-rays

We present simultaneous XMM-Newton UV and X-ray observations of the quadruply lensed quasar SDSS J1004+4112 (RBS 825). Simultaneously with the XMM-Newton observations we also performed integral field spectroscopy on the two closest lens images A and B using the Calar Alto PMAS spectrograph. In X-rays the widely spaced components C and D are clearly resolved, while the closer pair of images A and B is marginally resolved in the XMM-EPIC images. The integrated X-ray flux of the system has decreased by a factor of 6 since it was observed in the ROSAT All Sky Survey in 1990, while the X-ray spectrum became much harder with the power law index evolving from $\Gamma=-2.3$ to $\Gamma=-1.86$. By deblending the X-ray images of the lensed QSO we find that the X-ray flux ratios between the lens images A and B are significantly different from the simultaneously obtained UV ratios and previously measured optical flux ratios. Our optical spectrum of lens image A shows an enhancement in the blue emission line wings, which has been observed in previous epochs as a transient feature. We propose a scenario where intrinsic UV and X-ray variability gives rise to line variations which are selectively magnified in image A by microlensing. The extended emission of the lensing cluster of galaxies is clearly detected in the EPIC images, we measure a 0.5–2.0 keV luminosity of 1.4 $\times$ $10^{44}~{\rm erg/s}$. Based on the cluster X-ray properties, we estimate a mass of $2{-}6$ $\times$ $10^{14}~M_\odot$.

Effects of sedimented helium on the X-ray properties of galaxy clusters

Abstract In this Letter, we consider the role played by the sedimentation of helium nuclei on the emissivity and metallicity distribution of the X-ray emitting plasma in the cores of relaxed galaxy clusters. We model the gas density and temperature profiles of nearby cooling core clusters to estimate the gravitational acceleration acting on the helium, and show that its sedimentation time-scale is too long with respect to the present age of these objects to play a significant role. However, we argue that these time-scales definitely must have been lower in the past to allow the helium to settle in the cluster cooling cores and raise its abundance to values higher than the solar one. A direct consequence of this speculation is that the helium, by increasing the total X-ray emissivity, reduces the measured metal abundance in the inner (r ≲ 20 kpc) cluster regions.

An analytic investigation of the scatter in the integrated X-ray properties of galaxy groups and clusters

We revisit the scaling relationships between the dark matter mass and observed X-ray luminosity and temperature of galaxy clusters and groups in the local Universe. Specifically, we compare recent observations with analytic models of the intracluster medium in which the gas entropy distribution has been shifted by a variable amount, K o , to investigate the origin of the scatter in these scaling relations, and its influence on the luminosity and temperature functions. We find that variations in halo concentration or formation epoch (which might determine the time available for low-entropy gas to cool out) are insufficient to explain the amount of scatter in the mass and X-ray luminosity (M-L) relation. Instead, a range of entropy floors at a fixed halo mass, spanning approximately ∼50-700 keV cm 2 , is required to match the data. This range is likely related to the variance in heating and/or cooling efficiency from halo to halo. We demonstrate that these models are consistent with the observed temperature and luminosity functions of clusters, with a normalization of σ 8 ∼ 0.8 in agreement with Wilkinson Microwave Anisotropy Probe (WMAP) measurements (for h = 0.7 and Ω m = 0.3); in particular, the scatter in the M-L relation has an important influence on the shape of the luminosity function, and must be accounted for to provide a consistent result. Finally, we present predictions for the redshift evolution of these scaling relations and luminosity/temperature functions. Comparison with recent data at z < 0.7 shows reasonable agreement with a model that assumes a median entropy floor of K = 200 keV cm 2 . When observations are extended to group scales (kT ≤ 1 keV). this evolution will have the potential to discriminate between an entropy floor that is independent of redshift (e.g. in a preheating scenario) and one that depends on the cooling time of the halo.

Scaling Properties of X-ray Clusters: The Chandra View

The study of X-ray clusters of galaxies, started 30 years ago, has revealed an increasing complexity in the thermodynamics of the X-ray emitting intracluster medium (ICM) as long as the sensitivity and the resolution of the X-ray satellites increased. At the same time, deep surveysdetected several, unexpected, high-z clusters. Here we focus on the Chandra observations of the most distant X-ray selected clusters (0.3 < z < 1.3), in order to constrain their thermodynamic evolution. The X-ray scaling properties show hints of negative evolution in the luminosity–temperature and Mgas–temperature relations, and a positive evolution in the entropy–temperature relation. We find that the mean iron abundance at 〈z〉 = 0.8 is ZFe = 0.25+0.04−0.06Z⊙, and at 〈z〉 ∼ 1.2 is ZFe = 0.35+0.06−0.05Z⊙, both measures consistent with no evolution with respect to the local value ZFe≃ 0.3 Z⊙. These results can provide interesting constraints on the thermodynamics of the ICM at large look back times, pointing towards a redshift z ≳ 2 for the onset of non-gravitational processes.

Evolution atz≥ 0.5 of the X-ray properties of simulated galaxy clusters: comparison with observational constraints

We analyse the X-ray properties of a sample of local and high-redshift galaxy clusters extracted from a large cosmological hydrodynamical simulation. This simulation has been realized using the tree + SPH (smoothed particle hydrodynamic) code gadget-2 for a Λ-cold dark matter (ΛCDM) model. It includes radiative cooling, star formation and supernova feedback and allows the thermodynamic structure of clusters to be resolved radially up to redshift z= 1 in a way that is not yet completely accessible to observations. We consider only objects with Tew > 2 keV to avoid the large scatter in the physical properties present at the scale of groups and compare their properties to recent observational constraints. In our analysis, we adopt an approach that mimics observations, associating with each measurement an error comparable with recent observations and providing best-fitting results via robust techniques. Within the clusters, baryons are distributed among (i) a cold neutral phase, with a relative contribution that increases from less than 1 per cent to 3 per cent at higher redshift, (ii) stars, which contribute about 20 per cent, and (iii) the X-ray-emitting plasma, which contributes 80 (76) per cent at z= 0 (1) to the total baryonic budget. A depletion of the cosmic baryon fraction of ∼7 per cent (at z= 0) and 5 per cent (at z= 1) is measured at the virial radius, Rvir, in good agreement with adiabatic hydrodynamical simulations. We confirm that, also at redshift z > 0.5, power-law relations hold between the gas temperature T, the bolometric luminosity L, the central entropy S, the gas mass Mgas and the total gravitating mass Mtot, and that these relations are steeper than predicted by simple gravitational collapse. A significant negative evolution in the L–T and L–Mtot relations and positive evolution in the S–T relation are detected at 0.5 < z < 1 in this set of simulated galaxy clusters. This is partially consistent with recent analyses of the observed properties of z≳ 0.5 X-ray galaxy clusters. By fixing the slope to the values predicted by simple gravitational collapse, at high redshift we measure normalizations lower than the observed estimates by 10–40 per cent in the L–T, Mtot–T, Mgas–T, fgas–T and L–Mtot relations. This suggests either that the amount of hot X-ray-emitting plasma measured in the central regions of simulated systems is smaller than the observed one or that systematically higher values of gas temperatures and total masses than actually measured are recovered in the present simulated data set.

Models of the Intracluster Medium with Heating and Cooling: Explaining the Global and Structural X‐Ray Properties of Clusters

Nonradiative simulations that only include heating due to gravitational processes fail to match the observed mean X-ray properties of galaxy clusters. As a result, there has recently been increased interest in models in which either radiative or entropy injection (and/or redistribution) plays a central role in mediating the thermal and spatial properties of the intracluster medium. Both sets of models can account for the mean global properties of clusters. Radiative alone, however, results in fractions of cold/cooled baryons in excess of observationally established limits. On the other hand, the simplest entropy-injection models, by design, do not treat the cooling structure present in many clusters and cannot account for declining entropy profiles toward cluster centers revealed by recent high-resolution X-ray observations. We consider models that marry radiative with entropy injection, and confront model predictions for the global and structural properties of massive clusters with the latest X-ray data. The models successfully and simultaneously reproduce the observed luminosity-temperature (L-T) and luminosity-mass (L-M) relations, yield detailed entropy, surface brightness, and temperature profiles in excellent agreement with observations, and predict a cooled gas fraction that is consistent with observational constraints. More interestingly, the model provides a possible explanation for the significant intrinsic scatter present in the L-T and L-M relations. The model also offers a natural way of distinguishing between clusters classically identified as cooling clusters and the relaxed non-cooling clusters. The former correspond to systems that experienced only mild levels (300 keV cm2) of entropy injection, while the latter are identified as systems that had much higher entropy injection. The dividing line in entropy injection between the two categories corresponds roughly to the threshold for massive clusters. This finding suggests that entropy injection may be an important, if not the primary, factor in determining the class a particular cluster will belong to. These results also suggest that the previously identified relationship between inferred flow strength and the dispersion in the L-T relation is a manifestation of the distribution of cluster entropy-injection levels. This is borne out by the entropy profiles derived from Chandra and XMM-Newton. Finally, the model predicts a relationship between a cluster's central entropy and its core radius, the existence of which we confirm in the observational data.

X-ray properties of galaxy clusters and groups from a cosmological hydrodynamical simulation

We present results on the X-ray properties of clusters and groups of galaxies, extracted from a large cosmological hydrodynamical simulation. We used the TREE+SPH code GADGET to simulate a concordance A cold dark matter cosmological model within a box of 192 h -1 Mpc on a side, 480 3 dark matter particles and as many gas particles. The simulation includes radiative cooling assuming zero metallicity, star formation and supernova feedback. The very high dynamic range of the simulation allows us to cover a fairly large interval of cluster temperatures. We compute X-ray observables of the intracluster medium (ICM) for simulated groups and clusters and analyse their statistical properties. The simulated mass-temperature relation is consistent with observations once we mimic the procedure for mass estimates applied to real clusters. Also, with the adopted choices of Ω m = 0.3 and σ 8 = 0.8 for matter density and power spectrum normalization, respectively, the resulting X-ray temperature functton agrees with the most recent observational determinations. The luminosity-temperature relation also agrees with observations for clusters with T ≥ 2 keV. At the scale of groups, T ≥ 1 keV, we find no change of slope in this relation. The entropy in central cluster regions is higher than predicted by gravitational heating alone, the excess being almost the same for clusters and groups. We also find that the simulated clusters appear to have suffered some overcooling. We find f * ≃ 0.2 for the fraction of baryons in stars within clusters, thus approximately twice as large as the value observed. Interestingly, temperature profiles of simulated clusters are found to increase steadily toward cluster centres. They decrease in the outer regions, much like observational data do at r ≥ 0.2r vir , while not showing an isothermal regime followed by a smooth temperature decline in the innermost regions. Our results thus demonstrate the need for yet more efficient sources of energy feedback and/or the need to consider additional physical process which may be able to further suppress the gas density at the scale of poor clusters and groups, and, at the same time, to regulate the cooling of the ICM in central regions.

The First Detailed X-Ray Observations of High-Redshift, Optically Selected Clusters: XMM-Newton Results for Cl 1324+3011 at z = 0.76 and Cl 1604+4304 at z = 0.90

We present the first detailed X-ray observations of optically-selected clusters at high redshift. Two clusters, Cl 1324+3011 at z = 0.76 and Cl 1604+4304 at z = 0.90, were observed with XMM-Newton. The optical center of each cluster is coincident with an extended X-ray source whose emission is detected out to a radius of 0.5 Mpc. The emission from each cluster appears reasonably circular, with some indication of asymmetries and more complex morphologies. Similarly to other optically-selected clusters at redshifts of z > 0.4, both clusters are modest X-ray emitters with bolometric luminosities of only Lx = 1.4 - 2.0 x 10^(44) erg/s. We measure gas temperatures of T = 2.88 (+0.71/-0.49) keV for Cl 1324+3011 and 2.51 (+1.05/-0.69) keV for Cl 1604+4304. The X-ray properties of both clusters are consistent with the high-redshift Lx-T relation measured from X-ray-selected samples at z > 0.5. However, based on the local relations, their X-ray luminosities and temperatures are low for their measured velocity dispersions (sigma). The clusters are cooler by a factor of 2 - 9 compared to the local sigma-T relation. We briefly discuss the possible explanations for these results.

The X-Ray Properties of Nearby Abell Clusters from theROSATAll-Sky Survey: The Sample and Correlations with Optical Properties

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 20 cm 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 σ significance within a box of 2 × 2 h Mpc centered on Abell's position.

X-ray Emission from Stellar Clusters Near the Galactic Center

With the recent detection of X-ray emission from the Arches cluster, we examine the existing Chandra observations of the Galactic center region to determine X-ray properties of known stellar clusters and near-IR cluster candidates. We discuss the first detection of X-ray emission from the Quintuplet cluster, and find its emission characteristics very different from those of the Arches cluster. The X-ray and IR characteristics of these well-known clusters are used to discern if the candidate star clusters are indeed massive, Galactic center star clusters.

Iron abundances and heating of the intracluster medium in hydrodynamical simulations of galaxy clusters

Results from a large set of hydrodynamical smoothed particle hydrodynamics (SPH) simulations of galaxy clusters in a flat ΛCDM cosmology are used to investigate the metal enrichment and heating of the intracluster medium (ICM). The physical modelling of the gas includes radiative cooling, star formation, energy feedback and metal enrichment which follow from the explosions of supernovae of type II and Ia. The metallicity dependence of the cooling function is also taken into account. The gas is metal-enriched from star particles according to the SPH prescriptions. The simulations have been performed to study the dependence of final metal abundances and heating of the ICM on the numerical resolution and the model parameters. For a fiducial set of model prescriptions the results indicate radial iron profiles in broad agreement with observations; global iron abundances are also consistent with data. It is found that the iron distribution in the intracluster medium is critically dependent on the shape of the metal deposition profile. At large radii the radial iron abundance profiles in the simulations are steeper than those in the data, suggesting a dynamical evolution of simulated clusters different from those observed. For low-temperature clusters simulations yield iron abundances below the allowed observational range, unless a minimum diffusion length of metals in the ICM is introduced. The simulated emission-weighted radial temperature profiles are in good agreement with data for cooling flow clusters, but at very small distances from the cluster centres (∼2 per cent of the virial radii) the temperatures are a factor of ∼2 higher than the measured spectral values. The luminosity–temperature relation is in excellent agreement with the data; cool clusters (TX∼ 1 keV) have a core excess entropy of ∼200 keV cm2 and their X-ray properties are unaffected by the amount of feedback energy that has heated the ICM. The findings support the model proposed recently by Bryan, where the cluster X-ray properties are determined by radiative cooling. The fraction of hot gas fg at the virial radius increases with TX, and the distribution obtained from the simulated cluster sample is consistent with the observational ranges.

Constraining the cosmological parameters with the gas mass fraction in local and $\mathsf{{\vec z}&gt;0.7}$ galaxy clusters

We present a study of the baryonic fraction in galaxy clusters aimed at constraining the cosmological parameters , and the ratio between the pressure and density of the “dark” energy, w . We use results on the gravitating mass profiles of a sample of nearby galaxy clusters observed with the BeppoSAX X-ray satellite (Ettori et al. 2002) to set constraints on the dynamical estimate of . We then analyze Chandra observations of a sample of eight distant clusters with redshift in the range 0.72 and 1.27 and evaluate the geometrical limits on the cosmological parameters , and w by requiring that the gas fraction remains constant with respect to the look-back time. By combining these two independent probability distributions and using a priori distributions on both and H 0 peaked around primordial nucleosynthesis and HST-Key Project results respectively, we obtain that, at 95.4 per cent level of confidence, (i) , (ii) , for (corresponding to the case for a cosmological constant), and (iii) for a flat Universe. These results are in excellent agreement with the cosmic concordance scenario which combines constraints from the power spectrum of the Cosmic Microwave Background, the galaxy and cluster distribution, the evolution of the X-ray properties of galaxy clusters and the magnitude-redshift relation for distant type Ia supernovae. By combining our results with the latter method we further constrain and at the level.

The cluster wind from local massive star clusters

Results of a study of the theoretically predicted and observed X-ray properties of local massive star clusters are presented, with a focus on understanding the mass and energy flow from these clusters into the interstellar medium via a cluster wind. A simple theoretical model, based on the 1985 work of Chevalier & Clegg, is used to predict the theoretical cluster properties, and these are compared to those obtained from recent Chandra observations. The model includes the effect of lower energy transfer efficiency and mass loading. In spite of limited statistics, some general trends are indicated: the observed temperature of the diffuse X-ray emission is lower than that predicted from the stellar mass and energy input rates, but the predicted scaling of X-ray luminosity with cluster parameters is seen. The implications of these results are discussed.