22 research outputs found
The XMM Cluster Survey: Evidence for energy injection at high redshift from evolution of the X-ray luminosity-temperature relation
We measure the evolution of the X-ray luminosity-temperature (L_X-T) relation
since z~1.5 using a sample of 211 serendipitously detected galaxy clusters with
spectroscopic redshifts drawn from the XMM Cluster Survey first data release
(XCS-DR1). This is the first study spanning this redshift range using a single,
large, homogeneous cluster sample. Using an orthogonal regression technique, we
find no evidence for evolution in the slope or intrinsic scatter of the
relation since z~1.5, finding both to be consistent with previous measurements
at z~0.1. However, the normalisation is seen to evolve negatively with respect
to the self-similar expectation: we find E(z)^{-1} L_X = 10^{44.67 +/- 0.09}
(T/5)^{3.04 +/- 0.16} (1+z)^{-1.5 +/- 0.5}, which is within 2 sigma of the zero
evolution case. We see milder, but still negative, evolution with respect to
self-similar when using a bisector regression technique. We compare our results
to numerical simulations, where we fit simulated cluster samples using the same
methods used on the XCS data. Our data favour models in which the majority of
the excess entropy required to explain the slope of the L_X-T relation is
injected at high redshift. Simulations in which AGN feedback is implemented
using prescriptions from current semi-analytic galaxy formation models predict
positive evolution of the normalisation, and differ from our data at more than
5 sigma. This suggests that more efficient feedback at high redshift may be
needed in these models.Comment: Accepted for publication in MNRAS; 12 pages, 6 figures; added
references to match published versio
The XMM Cluster Survey: testing chameleon gravity using the profiles of clusters
The chameleon gravity model postulates the existence of a scalar field that couples with matter to mediate a fifth force. If it exists, this fifth force would influence the hot X-ray emitting gas filling the potential wells of galaxy clusters. However, it would not influence the clusters weak lensing signal. Therefore, by comparing X-ray and weak lensing profiles, one can place upper limits on the strength of a fifth force. This technique has been attempted before using a single, nearby cluster (Coma, z = 0.02). Here we apply the technique to the stacked profiles of 58 clusters at higher redshifts (0.1 < z < 1.2), including 12 new to the literature, using X-ray data from the XMM Cluster Survey and weak lensing data from the Canada-France-Hawaii-Telescope Lensing Survey. Using a multiparameter Markov chain Monte Carlo analysis, we constrain the two chameleon gravity parameters (beta and phi∞). Our fits are consistent with general relativity, not requiring a fifth force. In the special case of f(R) gravity (where beta = &surd;{1/6}), we set an upper limit on the background field amplitude today of |fR0| < 6 × 10-5 (95 per cent CL). This is one of the strongest constraints to date on |fR0| on cosmological scales. We hope to improve this constraint in future by extending the study to hundreds of clusters using data from the Dark Energy Survey
The XMM Cluster Survey: evolution of the velocity dispersion–temperature relation over half a Hubble time
We measure the evolution of the velocity dispersion–temperature (σv–TX) relation up to z = 1 using a sample of 38 galaxy clusters drawn from the XMM Cluster Survey. This work improves upon previous studies by the use of a homogeneous cluster sample and in terms of the number of high-redshift clusters included. We present here new redshift and velocity dispersion measurements for 12 z > 0.5 clusters observed with the Gemini Multi Object
Spectographs instruments on the Gemini telescopes. Using an orthogonal regression method,we find that the slope of the relation is steeper than that expected if clusters were self-similar, and that the evolution of the normalization is slightly negative, but not significantly different from zero (σv ∝T0.86±0.14E(z)−0.37±0.33). We verify our results by applying our methods to cosmological hydrodynamical simulations. The lack of evolution seen in our data is consistent with simulations that include both feedback and radiative cooling
The growth of intracluster light in XCS-HSC galaxy clusters from 0.1 < z < 0.5
We estimate the Intracluster Light (ICL) component within a sample of 18clusters detected in XMM Cluster Survey (XCS) data using deep (26.8 mag) Hyper Suprime Cam Subaru Strategic Program DR1 (HSC-SSP DR1)-band data. We apply a rest-frame isophotal threshold to our clusters, belowwhich we define light as the ICL within an aperture of (X-ray estimate of ) centered on the Brightest Cluster Galaxy(BCG). After applying careful masking and corrections for flux lossesfrom background subtraction, we recover 20% of the ICL flux,approximately four times our estimate of the typical background at thesame isophotal level ( 5%). We find that the ICL makes up about 24% of the total cluster stellar mass on average ( 41%including the flux contained in the BCG within 50 kpc); this value iswell-matched with other observational studies andsemi-analytic/numerical simulations, but is significantly smaller thanresults from recent hydrodynamical simulations (even when measured in anobservationally consistent way). We find no evidence for any linksbetween the amount of ICL flux with cluster mass, but find a growth rateof for the ICL between . We conclude that theICL is the dominant evolutionary component of stellar mass in clustersfrom . Our work highlights the need for a consistent approachwhen measuring ICL alongside the need for deeper imaging, in order tounambiguously measure the ICL across as broad a redshift range aspossible (e.g. 10-year stacked imaging from the Vera C. RubinObservatory)
The XMM Cluster Survey: Predicted overlap with the Planck Cluster Catalogue
We present a list of 15 clusters of galaxies, serendipitously detected by the
XMM Cluster Survey (XCS), that have a high probability of detection by the
Planck satellite. Three of them already appear in the Planck Early
Sunyaev-Zel'dovich (ESZ) catalogue. The estimation of the Planck detection
probability assumes the flat Lambda cold dark matter (LambdaCDM) cosmology most
compatible with 7-year Wilkinson Microwave Anisotropy Probe (WMAP7) data. It
takes into account the XCS selection function and Planck sensitivity, as well
as the covariance of the cluster X-ray luminosity, temperature, and integrated
comptonization parameter, as a function of cluster mass and redshift,
determined by the Millennium Gas Simulations. We also characterize the
properties of the galaxy clusters in the final data release of the XCS that we
expect Planck will have detected by the end of its extended mission. Finally,
we briefly discuss possible joint applications of the XCS and Planck data.Comment: Closely matches the version accepted for publication by MNRAS, 7
pages, 3 figures. The XCS-DR1 catalogue, together with optical and X-ray
(colour-composite and greyscale) images for each cluster, is publicly
available from http://xcs-home.org/datarelease
The XMM Cluster Survey: The Halo Occupation Number of BOSS galaxies in X-ray clusters
We present a direct measurement of the mean halo occupation distribution
(HOD) of galaxies taken from the eleventh data release (DR11) of the Sloan
Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey (BOSS). The HOD
of BOSS low-redshift (LOWZ: ) and Constant-Mass (CMASS: ) galaxies is inferred via their association with the dark-matter halos of
174 X-ray-selected galaxy clusters drawn from the XMM Cluster Survey (XCS).
Halo masses are determined for each galaxy cluster based on X-ray temperature
measurements, and range between .
Our directly measured HODs are consistent with the HOD-model fits inferred via
the galaxy-clustering analyses of Parejko et al. for the BOSS LOWZ sample and
White et al. for the BOSS CMASS sample. Under the simplifying assumption that
the other parameters that describe the HOD hold the values measured by these
authors, we have determined a best-fit alpha-index of 0.910.08 and
for the CMASS and LOWZ HOD, respectively. These
alpha-index values are consistent with those measured by White et al. and
Parejko et al. In summary, our study provides independent support for the HOD
models assumed during the development of the BOSS mock-galaxy catalogues that
have subsequently been used to derive BOSS cosmological constraints.Comment: Accepted for publication in MNRAS; 16 pages, 9 figures, 6 tables (1
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