The X‐Ray Concentration–Virial Mass Relation

Buote, David A.; Gastaldello, F.; Humphrey, Philip J.; Zappacosta, L.; Bullock, James S.; Brighenti, Fabrizio; Mathews, William G.

doi:10.1086/518684

Cited by 161 publications

(264 citation statements)

References 67 publications

(163 reference statements)

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“…Pointecouteau et al 2005;Vikhlinin et al 2005;Buote et al 2007;Schmidt & Allen 2007;Comerford & Natarajan 2007). For example, Buote et al (2007) find that the concentration-mass relation measured with a sample of 39 clusters agrees closely with the expectations in the framework of the concordance model. Allen et al (2008) use the cluster gas fraction to constrain the time evolution of the dark energy component of the universe.…”

Section: Introductionsupporting

confidence: 58%

Weighing simulated galaxy clusters using lensing and X-ray

Meneghetti

Rasia

Merten

et al. 2010

A&A

290

409

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Context. Among the methods employed to measure the mass of galaxy clusters, the techniques based on lensing and X-ray analyses are perhaps the most widely used; however, the comparison between these mass estimates is often difficult and, in several clusters, the results apparently inconsistent. Aims. We aim at investigating potential biases in lensing and X-ray methods to measure the cluster mass profiles. Methods. We performed realistic simulations of lensing and X-ray observations that were subsequently analyzed using observational techniques. The resulting mass estimates were compared with the input models. Three clusters obtained from state-of-the-art hydrodynamical simulations, each of which projected along three independent lines-of-sight, were used for this analysis. Results. We find that strong lensing models can be trusted over a limited region around the cluster core. Extrapolating the strong lensing mass models to outside the Einstein ring can lead to significant biases in the mass estimates, if the BCG is not modeled properly, for example. Weak-lensing mass measurements can be strongly affected by substructures, depending on the method implemented to convert the shear into a mass estimate. Using nonparametric methods which combine weak and strong lensing data, the projected masses within R 200 can be constrained with a precision of ∼10%. Deprojection of lensing masses increases the scatter around the true masses by more than a factor of two because of cluster triaxiality. X-ray mass measurements have much smaller scatter (about a factor of two less than the lensing masses), but they are generally biased toward low values between 5 and 10%. This bias is entirely ascribable to bulk motions in the gas of our simulated clusters. Using the lensing and the X-ray masses as proxies for the true and the hydrostatic equilibrium masses of the simulated clusters and by averaging over the cluster sample, we are able to measure the lack of hydrostatic equilibrium in the systems we have investigated. Conclusions. Although the comparison between lensing and X-ray masses may be difficult in individual systems due to triaxiality and substructures, using a large number of clusters with both lensing and X-ray observations may lead to important information about their gas physics and allow use of lensing masses to calibrate the X-ray scaling relations.

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Section: Introductionsupporting

confidence: 58%

Weighing simulated galaxy clusters using lensing and X-ray

Meneghetti

Rasia

Merten

et al. 2010

A&A

290

409

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“…(1). There is a clear dependence of f gas on temperature/mass, throughout the observed temperature range, in the sense that hotter, more massive systems have higher gas 8 The dependence of concentration on total mass is negligible for the mass range we consider here Buote et al 2007). …”

Section: Linking Entropy and Gas Mass Fractionmentioning

confidence: 92%

Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction

Pratt

Arnaud²,

Piffaretti³

et al. 2010

A&A

309

415

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We examine the radial entropy distribution and its scaling using 31 nearby galaxy clusters from the representative XMM-Newton cluster structure survey (REXCESS), a sample in the temperature range 2−9 keV selected in X-ray luminosity only, with no bias toward any particular morphological type. The entropy profiles are robustly measured at least out to R 1000 in all systems and out to R 500 in thirteen systems. Compared to theoretical expectations from non-radiative cosmological simulations, the observed distributions show a radial and mass-dependent excess entropy, such that the excess is greater and extends to larger radii in lower mass systems. At R 500 , the mass dependence and entropy excess are both negligible within the large observational and theoretical uncertainties. Mirroring this behaviour, the scaling of gas entropy is shallower than self-similar in the inner regions, but steepens with radius, becoming consistent with self-similar at R 500 . There is a large dispersion in scaled entropy in the inner regions, apparently linked to the presence of cool cores and dynamical activity; at larger radii the dispersion decreases by approximately a factor of two to 30 per cent, and the dichotomy between subsamples disappears. There are two peaks in the distribution of both inner slope and, after parameterising the profiles with a power law plus constant model, in central entropy K 0 . However, we are unable to distinguish between a bimodal or a left-skewed distribution of K 0 with the present data. The distribution of outer slopes is unimodal with a median value of 0.98, and there is a clear correlation of outer slope with temperature. Renormalising the dimensionless entropy profiles by the gas mass fraction profile f gas (

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“…The galaxies are selected with isolation criteria similar to ours, from the sample of O'Sullivan et al (2001b, and Helsdon et al (2001: NGC 6776 and NGC 2271, plus seven galaxies with a somewhat less stringent isolation radius of 0.4 Mpc, mostly upper limits), plus NGC 2865 (Fukazawa et al 2006), and NGC 821 (Pellegrini et al 2007). We also include four "fossil" groups (NGC 6482 and ESO306-17: O'Sullivan et al 2001b (note that the total mass of NGC 6482 could be significantly lower than typical fossil groups, see Buote et al 2007); NGC 1132: Mulchaey & Zabludoff 1999;and NGC 1600: Fukazawa et al 2006), which would also pass our isolation criteria, and 4 isolated early-type pairs (Grützbauch et al 2007). …”

Section: X-ray Emission From Isolated Galaxiesmentioning

confidence: 99%

The diverse X-ray properties of four truly isolated elliptical galaxies: NGC 2954, NGC 6172, NGC 7052, and NGC 7785

Memola¹,

Trinchieri²,

Wolter³

et al. 2009

A&A

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Aims. We investigate the X-ray properties of four isolated elliptical galaxies, selected from the Updated Zwicky Catalog according to strict isolation criteria. Isolated galaxies are not influenced by the group/cluster environment, and their X-ray emission can be studied independently of the often overwhelming contribution of the hot intergalactic medium. They are therefore suited to studying the X-ray characteristics relative to their intrinsic properties. Methods. We analyzed our own XMM-Newton and archival Chandra data in detail for three objects, and derived, when possible, the spatial and spectral characteristics of each source. An upper limit for the fourth one was obtained from archival ASCA data. We compared their characteristics with those of other 23 isolated objects for which X-ray and optical data are available in the literature. We explored possible theoretical explanations to interpret our results. Results. In spite of our attempt to select very homogeneous objects, both in terms of optical properties and environmental characteristics, we find a wide range in X-ray luminosities and L X /L B ratios for the four objects: two of them show a hot gaseous halo, whereas no gas is detected in the other two, to a factor >10 in luminosity. In fact, we find a large spread in the L X /L B for all galaxies considered, suggesting that the presence of hot gas is not easily related to the optical luminosity or to the mass, even in isolated systems. Younger objects tend to be less luminous in X-rays than older systems. However, it appears that older objects could span a wide range in luminosities.

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The X‐Ray Concentration–Virial Mass Relation

Cited by 161 publications

References 67 publications

Weighing simulated galaxy clusters using lensing and X-ray

Weighing simulated galaxy clusters using lensing and X-ray

Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction

The diverse X-ray properties of four truly isolated elliptical galaxies: NGC 2954, NGC 6172, NGC 7052, and NGC 7785

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