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Register a new userX-ray calibration of SZ scaling relations with the ACCEPT catalogue of galaxy clusters observed by Chandra
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B. Comis
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We explore the scaling relation between the flux of the Sunyaev-Zeldovich (SZ) effect and the total mass of galaxy clusters using already reduced Chandra X-ray data present in the ACCEPT (Archive of Chandra Cluster Entropy Profile Tables) catalogue. The analysis is conducted over a sample of 226 objects, examining the relatively small scale corresponding to a cluster overdensity equal to 2500 times the critical density of the background universe, at which the total masses have been calculated exploiting the hydrostatic equilibrium hypothesis. Core entropy (K0) is strongly correlated with the central cooling time, and is therefore used to identify cooling-core (CC) objects in our sample. Our results confirm the self-similarity of the scaling relation between the integrated Comptonization parameter (Y) and the cluster mass, for both CC and NCC (non-cooling-core) clusters. The consistency of our calibration with recent ones has been checked, with further support for Y as a good mass proxy. We also investigate the robustness of the constant gas fraction assumption, for fixed overdensity, and of the Yx proxy (Kravstov et al. 2007) considering CC and NCC clusters, again sorted on K0 from our sample. We extend our study to implement a K0-proxy, obtained by combining SZ and X-ray observables, which is proposed to provide a CC indicator for higher redshift objects. Finally, we suggest that an SZ-only CC indicator could benefit from the employment of deprojected Comptonization radial profiles.
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(Abridged) This is the second in a series of papers in which we derive simultaneous constraints on cosmology and X-ray scaling relations using observations of massive, X-ray flux-selected galaxy clusters. The data set consists of 238 clusters drawn from the ROSAT All-Sky Survey with 0.1-2.4 keV luminosities >2.5e44 erg/second, and incorporates extensive follow-up observations using the Chandra X-ray Observatory. Our analysis accounts self-consistently for all selection effects, covariances and systematic uncertainties. Here we describe the reduction of the follow-up X-ray observations, present results on the cluster scaling relations, and discuss their implications. Our constraints on the luminosity-mass and temperature-mass relations, measured within r_500, lead to three important results. First, the data support the conclusion that excess heating of the intracluster medium has altered its thermodynamic state from that expected in a simple, gravitationally dominated system; however, this excess heating is primarily limited to the central regions of clusters (r<0.15r_500). Second, the intrinsic scatter in the center-excised luminosity-mass relation is remarkably small, being undetected at the <10% level in current data; for the hot, massive clusters under investigation, this scatter is smaller than in either the temperature-mass or Y_X-mass relations (10-15%). Third, the evolution with redshift of the scaling relations is consistent with the predictions of simple, self-similar models of gravitational collapse, indicating that the mechanism responsible for heating the central regions of clusters was in operation before redshift 0.5 (the limit of our data) and that its effects on global cluster properties have not evolved strongly since then.
We present thermal Sunyaev-Zeldovich effect (SZE) measurements for 42 galaxy clusters observed at 150 GHz with the APEX-SZ experiment. For each cluster, we model the pressure profile and calculate the integrated Comptonization $Y$ to estimate the total thermal energy of the intracluster medium (ICM). We compare the measured $Y$ values to X-ray observables of the ICM from the literature (cluster gas mass $M_{rm{gas}}$, temperature $T_X$, and $Y_X =M_{rm{gas}}T_X$) that relate to total cluster mass. We measure power law scaling relations, including an intrinsic scatter, between the SZE and X-ray observables for three subsamples within the set of 42 clusters that have uniform X-ray analysis in the literature. We observe that differences between these X-ray analyses introduce significant variability into the measured scaling relations, particularly affecting the normalization. For all three subsamples, we find results consistent with a self-similar model of cluster evolution dominated by gravitational effects. Comparing to predictions from numerical simulations, these scaling relations prefer models that include cooling and feedback in the ICM. Lastly, we measure an intrinsic scatter of $sim28$ per cent in the $Y-Y_X,$ scaling relation for all three subsamples.
Well-determined scaling relations between X-ray observables and cluster mass are essential for using large cluster samples for cosmology. Cluster relations such as the Lx-T, M-T, Lx-M relations, have been investigated extensively, however the question remains whether these relations hold true also for groups. Some evidence supports a break at low masses, possibly caused by the influence of non-gravitational physics on low-mass systems. The main goal of this work is to test scaling relations for the low-mass range to check whether there is a systematic difference between clusters and groups, and to extend this method of reliable cluster mass determination for future samples down to the group regime. We compiled a statistically complete sample of 112 X-ray galaxy groups, 26 with Chandra data. Temperature, metallicity, and surface brightness profiles were created, and used to determine the main physical quantities and scaling relations. We then compared the group properties to the HIFLUGCS clusters and other samples. We present profiles and scaling relations of the whole sample. T and Z profiles behave universally, except for the cores. The Lx-T, M-T, Lx-M, Mg-M, M-Yx, and Lx-Yx relations are in good agreement with clusters. The Lx-T relation steepens for T<3keV, which could point to a larger impact of heating mechanisms on cooler systems. We found a strong drop in the gas mass fraction below 1keV, which indicates the ICM is less dominant in groups and the galaxies have a stronger influence on the system. In all relations the intrinsic scatter for groups is larger, which appears not correlated with merger activity but could be due to scatter caused by baryonic physics in the group cores. We also demonstrate the importance of selection effects. We have found evidence for a similarity break between groups and clusters. However this does not have a strong effect on scaling relations.
We present the X-ray properties and scaling relations of a large sample of clusters extracted from the Marenostrum MUltidark SImulations of galaxy Clusters (MUSIC) dataset. We focus on a sub-sample of 179 clusters at redshift z~0.11, with 3.2e14M_sun/h<M_vir<2e15Msun/h, complete in mass. We employed the X-ray photon simulator PHOX to obtain synthetic Chandra Observations and derive observable-like global properties of the intracluster medium (ICM), as X-ray temperature (T_X) and luminosity (L_X). T_X is found to slightly under-estimate the true mass-weighted temperature, although tracing fairly well the cluster total mass. We also study the effects of T_X on scaling relations with cluster intrinsic properties: total (M_500) and gas (M_g500) mass; integrated Compton parameter (Y_SZ) of the Sunyaev-Zeldovich (SZ) thermal effect; Y_X=M_g500 T_X. We confirm that Y_X is a very good mass proxy, with a scatter on M_500-Y_X and Y_SZ-Y_X lower than 5%. The study of scaling relations among X-ray, intrinsic and SZ properties indicates that MUSIC clusters reasonably resemble the self-similar prediction, especially for correlations involving T_X. The observational approach also allows for a more direct comparison with real clusters, from which we find deviations mainly due to the physical description of the ICM, affecting T_X and, particularly, L_X.
We report the scaling relations derived by fitting the X-ray parameters determined from analyzing the XMM-Newton observations of 120 galaxy clusters in the Planck Early Sunyaev-Zeldovich sample spanning the redshift range of 0.059$<$$z$$<$0.546. We find that the slopes of all the investigated scaling relations significantly deviate from the self-similar predictions, if self-similar redshift evolution is assumed. When the redshift evolution is left free to vary, the derived slopes are more in agreement with the self-similar predictions. Relaxed clusters have on average $sim$30$%$ higher X-ray luminosity than disturbed clusters at a given mass, a difference that, depending on the relative fraction of relaxed and disturbed clusters in the samples (e.g. SZ vs X-ray selected), have a strong impact in the normalization obtained in different studies. Using the core-excised cluster luminosities reduces the scatter and brings into better agreement the $L$-$M_{tot}$ and $L$-$T$ relations determined for different samples. $M_{tot}$-$T$, $M_{tot}$-$Y_X$, and $M_{tot}$-$M_{gas}$ relations show little dependence on the dynamical state of the clusters, but the normalizations of these relations may depend on the mass range investigated. Although most of the clusters investigated in this work reside at relatively low redshift, the fits prefer values of $gamma$, the parameter accounting for the redshift evolution, different from the self-similar predictions. This suggests an evolution ($<$2$sigma$ level, with the exception of the $M_{tot}$-$T$ relation) of the scaling relations. For the first time, we find significant evolution ($>$3$sigma$) of the $M_{tot}$-$T$ relation, pointing to an increase of the kinetic-to-thermal energy ratio with redshift. This is consistent with a scenario in which higher redshift clusters are on average more disturbed than their lower redshift counterparts.
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