scholarly journals Number Counts of Clusters of Galaxies in X-ray and Submm Bands

1999 ◽  
Vol 183 ◽  
pp. 255-255 ◽  
Author(s):  
Tetsu Kitayama ◽  
Shin Sasaki ◽  
Yasushi Suto
Keyword(s):  
Theoretical Models ◽  
Model Parameters ◽  
Clusters Of Galaxies ◽  
Cluster Number ◽  
Parameter Region ◽  
X Ray ◽  
Background Radiations ◽  
The Press ◽  
Number Counts ◽  
Acceptable Parameter

We compute the number counts of clusters of galaxies, the logN-logS relation, in several X-ray and submm bands on the basis of the Press—Schechter theory (Kitayama et al. 1998). We pay particular attention to a set of theoretical models which well reproduce the ROSAT 0.5–2 keV band logN-logS (Ebeling et al. 1997; Rosati et al. 1997), and explore possibilities to further constrain the models from future observations with ASCA and/or at submm bands. The latter is closely related to the European PLANCK mission and the Japanese LMSA project. We exhibit that one can break the degeneracy in an acceptable parameter region on the Ω0–σ8 plane by combining the ROSAT logN-logS and the submm number counts. Models which reproduce the ROSAT band logN-logS will have N(> S) ∼ (150–300)(S/10−12 erg cm−2 s−) −1.3 str−1 at S ≳ 10−12 erg cm−2 s−1 in the ASCA 2–10 keV band, and N(> Sv) ∼ (102–104)(Sv/100 mJy)−1.5 str−1 at Sv ≳ 100m J y in the submm (0.85mm) band. The amplitude of the logN-logS is very sensitive to the model parameters in the submm band. We also compute the redshift evolution of the cluster number counts and compare with that of the X-ray brightest Abell-type clusters (Ebeling et al. 1996). The results, although still preliminary, point to low density (Ω0 ∼ 0.3) universes. The contribution of clusters to the X-ray and submm background radiations is shown to be insignificant in any model compatible with the ROSAT logN-logS.

scholarly journals Evolution of the Cluster X-Ray Luminosity Function

1980 ◽  
Vol 92 ◽  
pp. 231-231
Author(s):  
Stephen C. Perrenod
Keyword(s):  
Power Law ◽  
Luminosity Function ◽  
Mass Function ◽  
Mass Relation ◽  
Clusters Of Galaxies ◽  
Supply Rate ◽  
X Ray ◽  
Abell Clusters ◽  
Number Counts ◽  
Gas Supply

I predict the evolution of the X-ray luminosity function of clusters of galaxies. Predominantly, I treat the assumption that galaxies form first, then cluster purely due to gravitation. I show that the richness distribution of Abell clusters favors this scenario, rather than the protocluster hypothesis. The luminosity function is produced by combining a generalized (for all Ω) Press-Schechter evolutionary mass function for clusters (derived herein) with a power law X-ray luminosity-mass relation; a power law relation is supported by observations of low-redshift clusters.I find very steep evolution in the luminosity function, and thus in the source counts, for large Ω, and moderate evolution for small Ω. For a variety of models for the gas supply rate to the intracluster medium, the evolution of the luminosity function does not vary greatly. Thus it appears that the Ω, dependence will dominate and that number counts of X-ray clusters will yield cosmological information. The power of a test of Ω with an evolving luminosity function is considerably enhanced relative to a test which involves solely global cosmological effects on a non-evolving population. This occurs because of the well-known result that, at late times, clustering tends to proceed slowly for universes of small Ω and rapidly for large Ω.

scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A1 ◽  
Author(s):  
F. Marulli ◽  
A. Veropalumbo ◽  
M. Sereno ◽  
L. Moscardini ◽  
F. Pacaud ◽  
...  
Keyword(s):  
Correlation Function ◽  
Galaxy Clusters ◽  
Cluster Number ◽  
X Ray ◽  
Mass Scaling ◽  
Cosmological Constraints ◽  
Density Peaks ◽  
Point Correlation ◽  
Point Correlation Function ◽  
Number Counts

Context.Galaxy clusters trace the highest density peaks in the large-scale structure of the Universe. Their clustering provides a powerful probe that can be exploited in combination with cluster mass measurements to strengthen the cosmological constraints provided by cluster number counts.Aims.We investigate the spatial properties of a homogeneous sample of X-ray selected galaxy clusters from the XXL survey, the largest programme carried out by theXMM-Newtonsatellite. The measurements are compared to Λ-cold dark matter predictions, and used in combination with self-calibrated mass scaling relations to constrain the effective bias of the sample,beff, and the matter density contrast, ΩM.Methods.We measured the angle-averaged two-point correlation function of the XXL cluster sample. The analysed catalogue consists of 182 X-ray selected clusters from the XXL second data release, with median redshift ⟨z⟩ = 0.317 and median mass ⟨M500⟩≃ 1.3 × 1014M⊙. A Markov chain Monte Carlo analysis is performed to extract cosmological constraints using a likelihood function constructed to be independent of the cluster selection function.Results.Modelling the redshift-space clustering in the scale range 10 <r[h−1Mpc] < 40, we obtain ΩM= 0.27−0.04+0.06andbeff= 2.73−0.20+0.18.This is the first time the two-point correlation function of an X-ray selected cluster catalogue at such relatively high redshifts and low masses has been measured. The XXL cluster clustering appears fully consistent with standard cosmological predictions. The analysis presented in this work demonstrates the feasibility of a cosmological exploitation of the XXL cluster clustering, paving the way for a combined analysis of XXL cluster number counts and clustering.

scholarly journals Constraints on the Matter Fluctuation Spectrum from X-Ray Cluster Number Counts

1998 ◽  
Vol 188 ◽  
pp. 314-314
Author(s):  
Tetsu Kitayama ◽  
Yasushi Suto
Keyword(s):  
Cold Dark Matter ◽  
Theoretical Modelling ◽  
Density Parameter ◽  
Cluster Number ◽  
New Approach ◽  
X Ray ◽  
Fluctuation Amplitude ◽  
Number Counts ◽  
Cosmological Constants ◽  
Best Fit

We find that the observed logN-logS relation of X-ray clusters (Ebeling et al. 1997; Rosati et al. 1997) can be reproduced remarkably well with a certain range of values for the fluctuation amplitude σ8 and the cosmological density parameter Ω0 in cold dark matter (CDM) universes (Kitayama & Suto 1997). The 1σ confidence limits on σ8 in the CDM models with n = 1 and h = 0.7 are expressed as (0.54 ± 0.02)Ω−0.35-0.82Ω0+0.55Ω200 (λ0 = 1 - Ω0) and (0.54 ± 0.02) Ω−0.28-0.91Ω0+0.68Ω200 (λ0 = 0), where n is the primordial spectral index, and h and λ0 are the dimensionless Hubble and cosmological constants. The errors quoted above indicate the statistical ones from the observed logN-logS only, and the systematic uncertainty from our theoretical modelling of X-ray flux in the best-fit value of σ8 is about 15%. In the case of n = 1, we find that the CDM models with (Ω0, λ0, h, σ8) ≃ (0.3, 0.7, 0.7, 1) and (0.45, 0, 0.7, 0.8) simultaneously account for the cluster logN-logS, X-ray temperature functions, and the normalization from the COBE 4 year data. The derived values assume the observations are without systematic errors, and we discuss in details other theoretical uncertainties which may change the limits on Ω0 and σ8 from the logN-logS relation. We have shown the power of this new approach which will become a strong tool as the observations attain more precision.

scholarly journals The Impact of Cooling Flows in Clusters of Galaxies

2000 ◽  
Vol 195 ◽  
pp. 199-206
Author(s):  
S. W. Allen
Keyword(s):  
Gravitational Lensing ◽  
Theoretical Models ◽  
Clusters Of Galaxies ◽  
X Ray ◽  
Cooling Flows ◽  
Cooling Flow ◽  
A Value ◽  
Best Fitting ◽  
The Mean ◽  
The Impact

I discuss the impact of cooling flows on the observable X-ray properties of clusters of galaxies. I show that accounting for the effects of cooling flows and subcluster merger events leads to consistent determinations of the distribution of gravitating matter in clusters from X-ray and gravitational lensing studies. Accounting for the effects of cooling flows significantly reduces the scatter in the LBol/TX relation determined for the hottest, most luminous systems and changes the best-fitting slope of the relation to a value close to LBol ∝ T2X, in agreement with theoretical models. A clear segregation between the mean metallicities of cooling-flow and non-cooling-flow clusters is observed, which can be explained by the presence of metallicity gradients in the cooling-flow systems.

scholarly journals Brightest cluster galaxies: the centre can(not?) hold

2020 ◽  
Vol 500 (1) ◽  
pp. 310-318
Author(s):  
Roberto De Propris ◽  
Michael J West ◽  
Felipe Andrade-Santos ◽  
Cinthia Ragone-Figueroa ◽  
Elena Rasia ◽  
...  
Keyword(s):  
Dark Matter ◽  
Local Environment ◽  
Major Axis ◽  
Theoretical Models ◽  
Dark Matter Halo ◽  
Gas Distribution ◽  
X Ray ◽  
Cluster Galaxies ◽  
Peculiar Velocities ◽  
Brightest Cluster Galaxies

ABSTRACT We explore the persistence of the alignment of brightest cluster galaxies (BCGs) with their local environment. We find that a significant fraction of BCGs do not coincide with the centroid of the X-ray gas distribution and/or show peculiar velocities (they are not at rest with respect to the cluster mean). Despite this, we find that BCGs are generally aligned with the cluster mass distribution even when they have significant offsets from the X-ray centre and significant peculiar velocities. The large offsets are not consistent with simple theoretical models. To account for these observations BCGs must undergo mergers preferentially along their major axis, the main infall direction. Such BCGs may be oscillating within the cluster potential after having been displaced by mergers or collisions, or the dark matter halo itself may not yet be relaxed.

scholarly journals A Systematic X‐Ray Search for Clusters of Galaxies behind the Milky Way. II. The Second CIZA Subsample

2007 ◽  
Vol 662 (1) ◽  
pp. 224-235 ◽  
Author(s):  
Dale D. Kocevski ◽  
Harald Ebeling ◽  
Chris R. Mullis ◽  
R. Brent Tully
Keyword(s):  
Milky Way ◽  
Clusters Of Galaxies ◽  
X Ray
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