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![ÈAn optical image of the central region of the X-ray cluster MS 1137.5]6625, with X-ray emission contours overlaid. The ROSAT HRI image was adaptively smoothed with Gaussians such that the product of the Gaussian widths and the number of counts inside that Gaussian was nearly constant. The contours start 3 p above the background (5.2 ] 10~3 counts s~1 arcmin~2) and increase in linear steps of 1.57 ] 10~3 counts s~1 arcmin~2. The maximum contour value displayed is 1.30 ] 10~2 counts s~1 arcmin~2. The galaxies are identiÐed according to Table 3.](profile/Isabella-Gioia/publication/230986979/figure/fig4/AS:668619885252610@1536422811059/EAn-optical-image-of-the-central-region-of-the-X-ray-cluster-MS-113756625-with-X-ray.png)
ÈAn optical image of the central region of the X-ray cluster MS 1137.5]6625, with X-ray emission contours overlaid. The ROSAT HRI image was adaptively smoothed with Gaussians such that the product of the Gaussian widths and the number of counts inside that Gaussian was nearly constant. The contours start 3 p above the background (5.2 ] 10~3 counts s~1 arcmin~2) and increase in linear steps of 1.57 ] 10~3 counts s~1 arcmin~2. The maximum contour value displayed is 1.30 ] 10~2 counts s~1 arcmin~2. The galaxies are identiÐed according to Table 3.
Source publication
We report on our ASCA, Keck, and ROSAT observations of MS 1137.5+6625, the second most distant cluster of galaxies in the Einstein Extended Medium Sensitivity Survey (EMSS), at redshift 0.78. We now have a full set of X-ray temperatures, optical velocity dispersions, and X-ray images for a complete, high-redshift sample of clusters of galaxies draw...
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Citations
... The superscripts in column one indicate the origin of redshift data when it did not come from our own observations. 1 also known as MS1054-03 was observed with Keck for 8.6 hours (Tran et al. 1999). 2 was observed with Keck (Donahue et al. 1999). 3 also known as RXJ1821.6+6827 was observed with CFHT, Keck and the 2.2 m telescope at the University of Hawaii (Gioia et al. 2004). ...
We measure the evolution of the velocity dispersion--temperature
($\sigma_{\rm v}$--$T_{\rm X}$) relation up to $z = 1$ using a sample of 38
galaxy clusters drawn from the \textit{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 GMOS 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 normalisation is
slightly negative, but not significantly different from zero ($\sigma_{\rm v}
\propto T^{0.86 \pm 0.14} E(z)^{-0.37 \pm 0.33}$). We verify our results by
applying our methods to cosmological hydrodynamical simulations. The lack of
evolution seen from the data suggests that the feedback does not significantly
heat the gas, a result that is consistent with simulations including radiative
cooling.
Clusters constitute a very rich source of information for cosmology. Their present day abundance can be used to found the normalization and the shape of the power spectrum. Clusters can also be used to determine the parameter density of the universe Ω − 0. The evolution of their number density is a powerful cosmological global test of the mean density of the Universe. It is fashionable to claim that the abundance of clusters does not change very much with clusters redshift and therefore favor a low density universe. This is an overstatement and analyses based on the most recent data rather favor a high density universe. The baryon fraction in clusters is an alternative method to derive the mean density of the Universe. Here again, taking into account several biases in the baryon fraction is derived from data, the actual baryon fraction seen in clusters can be reconcilied with a high density universe.
The Gemini/HST Galaxy Cluster Project (GCP) covers 14 z=0.2-1.0 clusters with X-ray luminosity of L_500 >= 10^44 ergs/s in the 0.1-2.4 keV band. In this paper we provide homogeneously calibrated X-ray luminosities, masses and radii, and we present the complete catalog of the ground-based photometry for the GCP clusters. The clusters were observed with Gemini North or South in three or four of the optical passbands g', r', i' and z'. The photometric catalog includes consistently calibrated total magnitudes, colors, and geometrical parameters. The photometry reaches ~25 mag in the passband closest to rest frame B-band. We summarize comparisons of our photometry with data from the Sloan Digital Sky Survey. We describe the sample selection for our spectroscopic observations, and establish the calibrations to obtain rest frame magnitudes and colors. Finally, we derive the color-magnitude relations for the clusters and briefly discuss these in the context of evolution with redshift. Consistent with our results based on spectroscopic data, the color-magnitude relations support passive evolution of the red-sequence galaxies. The absence of change in the slope with redshift, constrains the allowable age variation along the red sequence to <0.05 dex between the brightest cluster galaxies and those four magnitudes fainter. The paper serves as the main reference for the GCP cluster and galaxy selection, X-ray data and ground-based photometry.
We report the results of a study which assembles deep observations with the ACIS-I instrument on the Chandra observatory to study the evolution in the core properties of a sample of galaxy groups and clusters out to redshifts z ≈ 1.3. A search for extended objects within these fields yields a total of 62 systems for which redshifts are available,
and we added a further 24 non-X-ray-selected clusters, to investigate the impact of selection effects and improve our statistics
at high redshift. Six different estimators of cool core strength are applied to these data: the entropy (K) and cooling time (tcool) within the cluster core, the cooling time as a fraction of the age of the Universe (tcool/tUni) and three estimators based on the cuspiness of the X-ray surface brightness profile. A variety of statistical tests are
used to quantify evolutionary trends in these cool core indicators. In agreement with some previous studies, we find that
there is significant evolution in tcool/tUni, but little evolution in tcool, suggesting that gas is accumulating within the core, but that the cooling time deep in the core is controlled by active
galactic nucleus (AGN) feedback. We show that this result extends down to the group regime and appears to be robust against
a variety of selection biases (detection bias, archival biases and biases due to the presence of central X-ray AGN) which
we consider.
Aims: Observations and cosmological simulations show galaxy clusters as a family of nearly self-similar objects with properties that can be described by scaling relations as a function of mass and time. Here we study the scaling relations between the galaxy velocity dispersion (σv) and X-ray quantities, such as X-ray bolometric luminosity (LBolX,500) and temperature (TX) in galaxy clusters at high redshifts (0.64 ≤ z ≤ 1.46). We also compare our results with the analogous study of the local HIFLUGCS sample. Methods: For the analysis, we use a set of 15 distant galaxy clusters extracted from the literature and selected via different methods. We also use a sample of ten newly discovered clusters selected via their X-ray emission by the XMM-Newton Distant Cluster Project (XDCP), with more than ten confirmed spectroscopic members per cluster. For both samples, the same method was used to determine σv. We also study the evolution of this scaling relation by comparing the high redshift results with the data from the HIFLUGCS sample, which is taken as a representative of the conditions in the local Universe. For such an analysis, we restrict the study to the clusters in the common LBolX,500 range. We also investigate the LX - TX and the σv - TX relations for the 15 clusters from the literature sample. Results: We report the results of the X-ray and kinematic analysis of ten newly detected high redshift clusters and provide their spectroscopic and kinematic details. For the entire distant sample, we find a slope fully consistent with the one typical of local clusters, albeit with a large associated uncertainty (~26%). We repeat the fit by freezing the slope to the value found for the HIFLUGCS systems restricted to the same luminosity range as our sample to investigate the evolution of the amplitude alone. We find a positive offset of ΔA/A = 0.44 ± 0.22 if the self-similar evolution is neglected, hence indicating the possible need for including evolutionary effects. However, the LX - TX relation is found to be in good agreement with the local relation without any significant redshift evolution. Finally, the σv - TX relation appears to slightly deviate from the theoretical expectation that galaxies and gas particles have a similar specific kinetic energy. However, the associated uncertainty is currently too large for making any conclusive statement in this regard.Appendices are available in electronic form at http://www.aanda.org
We analyzed the luminosity-temperature-mass of gas (L
X
−T−M
g
) relations for a sample of 21 Chandra galaxy clusters. We used the standard approach (β−model) to evaluate these relations for our sample that differs from other catalogues since it considers galaxy clusters at higher redshifts (0.4<z<1.4). We assumed power-law relations in the form
$L_{X} \sim(1 +z)^{A_{L_{X}T}} T^{\beta_{L_{X}T}}$
,
$M_{g} \sim(1 + z)^{A_{M_{g}T}} T^{\beta_{M_{g}T}}$
, and
$M_{g} \sim(1 + z)^{A_{M_{g}L_{X}}} L^{\beta_{M_{g}L_{X}}}$
. We obtained the following fitting parameters with 68 % confidence level:
$A_{L_{X}T} = 1.50 \pm0.23$
,
$\beta_{L_{X}T} = 2.55 \pm0.07$
;
$A_{M_{g}T} = -0.58 \pm0.13$
and
$\beta_{M_{g}T} = 1.77 \pm0.16$
;
$A_{M_{g}L_{X}} \approx-1.86 \pm0.34$
and
$\beta_{M_{g}L_{X}} = 0.73 \pm0.15$
, respectively. We found that the evolution of the M
g
−T relation is small, while the M
g
−L
X
relation is strong for the cosmological parameters Ω
m
=0.27 and Ω
Λ
=0.73. In overall, the clusters at high-z have stronger dependencies between L
X
−T−M
g
correlations, than those for clusters at low-z. For most of galaxy clusters (first of all, from MACS and RCS surveys) these results are obtained for the first time.
Observations and cosmological simulations show galaxy clusters as a family of
nearly self-similar objects with properties that can be described by scaling
relations as a function of e.g. mass and time. Here we study the scaling
relations between the galaxy velocity dispersion and X-ray quantities like
X-ray bolometric luminosity and temperature in galaxy clusters at high
redshifts (0.64 $\leq$ z $\leq$ 1.46). We also compare our results with the
similar study of the local HIFLUGCS sample. For the analysis, we use a set of
15 distant galaxy clusters extracted from the literature plus a sample of 10
newly discovered clusters selected in X-rays by the \XMM Distant Cluster
Project (XDCP) with more than 10 confirmed spectroscopic members per cluster.
We also study the evolution of this scaling relation by comparing the high
redshift results with the data from the local HIFLUGCS sample. We also
investigated the $L_X - T_X$ and the $\sigma_v - T_X$ relations for the 15
clusters in the literature sample. We report the results of the X-ray and
kinematic analysis of 10 newly detected high redshift clusters and provide
their spectroscopic and kinematic details. For the entire, distant sample we
find a slope fully consistent with the one typical of local clusters, albeit
with a large associated uncertainty. The study on the evolution of the
amplitude reveals a positive offset if the self-similar evolution is neglected,
hence possibly indicating the need for including evolutionary effects. However,
the $L_X - T_X$ relation is found to be in good agreement with the local
relation without any significant redshift evolution. Finally, the $\sigma_v -
T_X$ relation appears to slightly deviate from the theoretical expectation that
galaxies and gas particles have a similar specific kinetic energy. However, the
associated uncertainty is currently too large for making any conclusive
statement in this regard.
We conduct a deep mid-infrared (mid-IR) census of nine massive galaxy clusters at (0 < z < 1.3) with a total of ~1500 spectroscopically confirmed member galaxies using Spitzer/IRAC photometry and established mid-IR color selection techniques. Of the 949 cluster galaxies that are detected in at least three of the four IRAC channels at the ≥3? level, we identify 12 that host mid-IR-selected active galactic nuclei (IR-AGNs). To compare the IR-AGNs across our redshift range, we define two complete samples of cluster galaxies: (1) optically selected members with rest-frame V
AB magnitude < ? 21.5 and (2) mid-IR-selected members brighter than (M*3.6 + 0.5), i.e., essentially a stellar mass cut. In both samples, we measure f
IR-AGN ~ 1% with a strong upper limit of ~3% at z < 1. This uniformly low IR-AGN fraction at z < 1 is surprising given that the fraction of 24 ?m sources in the same galaxy clusters is observed to increase by about a factor of four from z ~ 0 to z ~ 1; this indicates that most of the detected 24 ?m flux is due to star formation. Only in our single galaxy cluster at z = 1.24 is the IR-AGN fraction measurably higher at ~15% (all members; ~70% for late-types only). In agreement with recent studies, we find that the cluster IR-AGNs are predominantly hosted by late-type galaxies with blue optical colors, i.e., members with recent/ongoing star formation. The four brightest IR-AGNs are also X-ray sources; these IR+X-ray AGNs all lie outside the cluster core (R
proj 0.5?Mpc) and are hosted by highly morphologically disturbed members. Although our sample is limited, our results suggest that f
IR-AGN in massive galaxy clusters is not strongly correlated with star formation at z < 1 and that IR-AGNs have a more prominent role at z 1.
We study the mid-infrared properties of 1315 spectroscopically confirmed members in eight massive (Mvirgtrsim 5 × 1014 Msun) galaxy clusters covering the redshift range from 0.02 to 0.83. The selected clusters all have deep Spitzer/MIPS 24 μm observations, Hubble and ground-based photometry, and extensive redshift catalogs. We observe for the first time an increase in the fraction of cluster galaxies with mid-infrared star formation rates higher than 5 Msun yr−1 from 3% at z = 0.02 to 13% at z = 0.83 (RP ≤ 1 Mpc). This increase is reproduced even when considering only the most massive members (M* ≥ 4 × 1010 Msun). The 24 μm observations reveal stronger evolution in the fraction of blue/star-forming cluster galaxies than in color-selected samples: the number of dusty, strongly star-forming cluster galaxies increases with redshift, and combining these with the optically defined Butcher-Oemler members [Δ (B − V) < − 0.2] doubles the total fraction of blue/star-forming galaxies in the inner Mpc of the clusters to ~23% at z = 0.83. These results, the first of our Spitzer/MIPS Infra-Red Cluster Survey (SMIRCS), support earlier studies indicating that the increase in star-forming members is driven by cluster assembly and galaxy infall, as is expected in the framework of hierarchical formation.
We analyzed the luminosity-temperature-mass of gas (L_{X} - T - M_{g})
relation for sample of galaxy clusters that have been observed by the Chandra
satellite. We used 21 high-redshift clusters (0.4 < z < 1.4).
We assumed a power-law relation between the X-ray luminosity of galaxy
clusters and its temperature and redshift L_{X} ~
(1+z)^{A_{L_{X}T}}T^{beta_{L_{X}T}}. We obtained that for an Omega_{m} = 0.27
and Lambda = 0.73 universe, A_{L_{X}T} = 1.50 +/- 0.23, beta_{L_{X}T} = 2.55
+/- 0.07 (for 68% confidence level).
Then, we found the evolution of M_{g} - T relation is small. We assumed a
power-law relation in the form M_{g} ~ (1+z)^{A_{M_{g}T}}T^{beta_{M_{g}T}}
also, and we obtained A_{M_{g}T} = -0.58 +/- 0.13 and beta_{M_{g}T} = 1.77 +/-
0.16. We also obtained the evolution in M_{g} - L_{X} relation, we can conclude
that such relation has strong evolution for our cosmological parameters. We
used M_{g} ~ (1+z)^{A_{M_{g}L_{X}}}L^{beta_{M_{g}L_{X}}} equation for assuming
this relation and we found A_{M_{g}L_{X}} ~ -1.86 +/- 0.34 and
beta_{M_{g}L_{X}} = 0.73 +/- 0.15 for Omega_{m} = 0.27 and Lambda = 0.73
universe.
In overal, the clusters on big redshifts have much stronger evolution between
correlations of luminosity, temperature and mass, then such correlations for
clusters at small redshifts. We can conclude that such strong evolution in
L_{X} - T - M_{g} correlations indicate that in the past the clusters have
bigger temperature and higher luminosity.
