Outskirts of Galaxy Clusters

Reiprich, T. H.; Basu, Kaustuv; Ettori, S.; Israel, Holger; Lovisari, Lorenzo; Molendi, S.; Pointecouteau, É.; Roncarelli, M.

doi:10.1007/s11214-013-9983-8

Cited by 159 publications

(196 citation statements)

References 277 publications

(390 reference statements)

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“…We are unlikely to improve upon this limit (see, e.g. Vazza et al 2011, Reiprich et al 2013) with the current generation of instrumentation. In Figure 7 we also show the predicted surface brightness from a uniform density cloud of gas with kT = 0.5 keV, Z = 0.2Z , and n = 200ρcΩ b extending out to the virial radius.…”

Section: Missing Baryons From Ngc 1961mentioning

confidence: 99%

A deepXMM–Newtonstudy of the hot gaseous halo around NGC 1961

Anderson

Churazov

Bregman

2015

Mon. Not. R. Astron. Soc.

104

118

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We examine 11 XMM-Newton observations of the giant spiral galaxy NGC 1961, allowing us to study the hot gaseous halo of a spiral galaxy in unprecedented detail. We perform a spatial and a spectral analysis; with the former, the hot halo is detected to at least 80 kpc and with the latter its properties can be measured in detail up to 42 kpc. We find evidence for a negative gradient in the temperature profile as is common for elliptical galaxies. We measure a rough metallicity profile, which is consistent with being flat at Z ∼ 0.2Z . Converting to this metallicity, the deprojected density profile is consistent with previous parametric fits, with no evidence for a break within 42 kpc (∼0.1R vir ). Extrapolating to the virial radius, we infer a hot halo mass comparable to the stellar mass of the galaxy, and a baryon fraction from the stars and hot gas of around 30%. The cooling time of the hot gas is orders of magnitude longer than the dynamical time, making the hot halo stable against cooling instabilities, and we argue that an extended stream of neutral Hydrogen seen to the NW of this galaxy is instead likely due to accretion from the intergalactic medium. The low metallicity of the hot halo suggests it too was likely accreted. We compare the hot halo of NGC 1961 to hot halos around isolated elliptical galaxies, and show that the total mass determines the hot halo properties better than the stellar mass.

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Section: Missing Baryons From Ngc 1961mentioning

confidence: 99%

A deepXMM–Newtonstudy of the hot gaseous halo around NGC 1961

Anderson

Churazov

Bregman

2015

Mon. Not. R. Astron. Soc.

104

118

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“…Rather, we fit a global T X (Table 1; V09a) and assume the empirical average temperature profile T X (r) = T X (1.19−0.84r/r 200 ) Reiprich et al (2013) derive from compiling all available Suzaku Equation (4) provides us with a cumulative mass profile. We evaluate this profile at some r test , e.g.…”

Section: X-ray Analysismentioning

confidence: 99%

The 400d Galaxy Cluster Survey weak lensing programme

Israel

Reiprich²,

Erben³

et al. 2014

A&A

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Context. Scaling properties of galaxy cluster observables with cluster mass provide central insights into the processes shaping clusters. Calibrating proxies for cluster mass that are relatively cheap to observe will moreover be crucial to harvest the cosmological information available from the number and growth of clusters with upcoming surveys like eROSITA and Euclid. The recent Planck results led to suggestions that X-ray masses might be biased low by ∼40%, more than previously considered. Aims. We aim to extend knowledge of the weak lensing -X-ray mass scaling towards lower masses (as low as 1 × 10 14 M ) in a sample representative of the z ∼ 0.4-0.5 population. Thus, we extend the direct calibration of cluster mass estimates to higher redshifts. Methods. We investigate the scaling behaviour of MMT/Megacam weak lensing (WL) masses for 8 clusters at 0.39 ≤ z ≤ 0.80 as part of the 400d WL programme with hydrostatic Chandra X-ray masses as well as those based on the proxies, e.g. Y X = T X M gas . Results. Overall, we find good agreement between WL and X-ray masses, with different mass bias estimators all consistent with zero. When subdividing the sample into a low-mass and a high-mass subsample, we find the high-mass subsample to show no significant mass bias while for the low-mass subsample, there is a bias towards overestimated X-ray masses at the ∼2σ level for some mass proxies. The overall scatter in the mass-mass scaling relations is surprisingly low. Investigating possible causes, we find that neither the greater range in WL than in X-ray masses nor the small scatter can be traced back to the parameter settings in the WL analysis. Conclusions. We do not find evidence for a strong (∼40%) underestimate in the X-ray masses, as suggested to reconcile recent Planck cluster counts and cosmological constraints. For high-mass clusters, our measurements are consistent with other studies in the literature. The mass dependent bias, significant at ∼2σ, may hint at a physically different cluster population (less relaxed clusters with more substructure and mergers); or it may be due to small number statistics. Further studies of low-mass high-z lensing clusters will elucidate their mass scaling behaviour.

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“…the hydrogen like Fe-K line, increase with higher gas temperatures (e.g., Fig. 2 in Reiprich et al 2013). Analogously to the temperature, the spectrum also reflects the density and the metallicity of the ICM, as well as the cluster redshift, which allows these properties to be recovered in the analysis of X-ray data.…”

Section: Introductionmentioning

confidence: 98%

Constraining galaxy cluster temperatures and redshifts with eROSITA survey data

Borm

Reiprich

Mohammed

et al. 2014

A&A

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Context. The nature of dark energy is imprinted in the large-scale structure of the Universe and thus in the mass and redshift distribution of galaxy clusters. The upcoming eROSITA instrument will exploit this method of probing dark energy by detecting ∼100 000 clusters of galaxies in X-rays. Aims. For a precise cosmological analysis the various galaxy cluster properties need to be measured with high precision and accuracy. To predict these characteristics of eROSITA galaxy clusters and to optimise optical follow-up observations, we estimate the precision and the accuracy with which eROSITA will be able to determine galaxy cluster temperatures and redshifts from X-ray spectra. Additionally, we present the total number of clusters for which these two properties will be available from the eROSITA survey directly. Methods. We simulate the spectra of galaxy clusters for a variety of different cluster masses and redshifts while taking into account the X-ray background as well as the instrumental response. An emission model is then fit to these spectra to recover the cluster temperature and redshift. The number of clusters with precise properties is then based on the convolution of the above fit results with the galaxy cluster mass function and an assumed eROSITA selection function. Results. During its four years of all-sky surveys, eROSITA will determine cluster temperatures with relative uncertainties of ∆T/T 10% at the 68%-confidence level for clusters up to redshifts of z ∼ 0.16 which corresponds to ∼1670 new clusters with precise properties. Redshift information itself will become available with a precision of ∆z/(1 + z) 10% for clusters up to z ∼ 0.45. Additionally, we estimate how the number of clusters with precise properties increases with a deepening of the exposure. For the above clusters, the fraction of catastrophic failures in the fit is below 20% and in most cases it is even much smaller. Furthermore, the biases in the best-fit temperatures as well as in the estimated uncertainties are quantified and shown to be negligible in the relevant parameter range in general. For the remaining parameter sets, we provide correction functions and factors. In particular, the standard way of estimating parameter uncertainties significantly underestimates the true uncertainty, if the redshift information is not available. Conclusions. The eROSITA survey will increase the number of galaxy clusters with precise temperature measurements by a factor of 5-10. Thus the instrument presents itself as a powerful tool for the determination of tight constraints on the cosmological parameters. At the same time, this sample of clusters will extend our understanding of cluster physics, e.g. through precise L X − T scaling relations.

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Outskirts of Galaxy Clusters

Cited by 159 publications

References 277 publications

A deepXMM–Newtonstudy of the hot gaseous halo around NGC 1961

A deepXMM–Newtonstudy of the hot gaseous halo around NGC 1961

The 400d Galaxy Cluster Survey weak lensing programme

Constraining galaxy cluster temperatures and redshifts with eROSITA survey data

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