Entropy scaling in galaxy clusters: Insights from an<b><i>XMM-Newton</i></b>observation of the poor cluster A1983

Pratt, G. W.; Arnaud, M.

doi:10.1051/0004-6361:20030844

Cited by 96 publications

(135 citation statements)

References 68 publications

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“…The observed gas profile in the outer regions fits well to a beta-model with a density slope of 3β gas ¼ α gas (where ρ gas ∝ r −α gas ). We use observations that have small uncertainties on the gas-density slope at large radii and that cover our entire cluster mass range (12,(33)(34)(35)(36). 72 M ⊙ ).…”

Section: Observations Analysis and Resultsmentioning

confidence: 99%

Searching for the missing baryons in clusters

Rasheed¹,

Bahcall²,

Bode³

2011

Proc. Natl. Acad. Sci. U.S.A.

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Observations of clusters of galaxies suggest that they contain fewer baryons (gas plus stars) than the cosmic baryon fraction. This "missing baryon" puzzle is especially surprising for the most massive clusters, which are expected to be representative of the cosmic matter content of the universe (baryons and dark matter). Here we show that the baryons may not actually be missing from clusters, but rather are extended to larger radii than typically observed. The baryon deficiency is typically observed in the central regions of clusters (∼0.5 the virial radius). However, the observed gas-density profile is significantly shallower than the mass-density profile, implying that the gas is more extended than the mass and that the gas fraction increases with radius. We use the observed density profiles of gas and mass in clusters to extrapolate the measured baryon fraction as a function of radius and as a function of cluster mass. We find that the baryon fraction reaches the cosmic value near the virial radius for all groups and clusters above ∼5 × 10 13 h −1 72 M ⊙ . This suggests that the baryons are not missing, they are simply located in cluster outskirts. Heating processes (such as shock-heating of the intracluster gas, supernovae, and Active Galactic Nuclei feedback) likely contribute to this expanded distribution. Upcoming observations should be able to detect these baryons.cosmology | hot intracluster gas C lusters of galaxies, the largest virialized systems in the universe, are powerful tools in constraining cosmology and tracing the large-scale structure of the universe (1-4, and references therein). The large mass of clusters (∼10 14 to 10 15 h −1 72 M ⊙ ) implies that their contents-dark and baryonic matter-have been accreted from very large regions of ∼10 comoving Mpc, and therefore should be representative of the mean matter content of the universe; on these large scales there are no clear mechanisms to separate dark and baryonic matter (e.g., refs. 5 and 6). The strong gravitational potential of clusters also implies that baryons cannot easily escape from these systems. Therefore, clusters are expected to retain the cosmic baryon fraction, the relative fraction of baryons to total matter on large scales. This basic expectation of a representative baryon fraction in clusters was used in 1993 (6) to suggest that the mass-density of the universe must be low, since the observed baryon fraction in clusters was considerably larger than expected for a critical density universe. Most of the baryons in clusters reside in the X-ray emitting hot intracluster gas, which approximately traces the cluster gravitational potential dominated by dark matter. The rest of the baryons are in the luminous galaxies and in isolated stars that comprise the small amount of faint diffuse intracluster light (ICL).A puzzle has been raised, however, over the last few years: Detailed X-ray observations from Chandra, XMM-Newton, and ROSAT suggest that the cluster baryon fraction (gas plus stars relative to total mass) is considerably low...

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Section: Observations Analysis and Resultsmentioning

confidence: 99%

Searching for the missing baryons in clusters

Rasheed¹,

Bahcall²,

Bode³

2011

Proc. Natl. Acad. Sci. U.S.A.

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“…However, simulations have shown that the resulting entropy profiles of the simulated groups are much too flat compared to observations (Borgani et al 2005;Younger & Bryan 2007). Therefore the observed lack of iso-entropic core entropy profiles in groups and poor clusters has shown that simple preheating is unlikely to be the sole explanation of the observations (Ponman et al 2003;Pratt & Arnaud 2003). Ettori et al (2004b) using a simulation that included radiative cooling, star formation and supernova feedback, found a significant negative evolution in the normalization of the L X − T and S − T relations in objects selected in the range 0.5 < z < 1.…”

Section: Interpretation Of Scaling Relations With Simulationsmentioning

confidence: 90%

Scaling Relations for Galaxy Clusters: Properties and Evolution

et al. 2013

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Well-calibrated scaling relations between the observable properties and the total masses of clusters of galaxies are important for understanding the physical processes that give rise to these relations. They are also a critical ingredient for studies that aim to constrain cosmological parameters using galaxy clusters. For this reason much effort has been spent during the last decade to better understand and interpret relations of the properties of the intra-cluster medium. Improved X-ray data have expanded the mass range down to galaxy groups, whereas SZ surveys have openened a new observational window on the intracluster medium. In addition, continued progress in the performance of cosmological simulations has allowed a better understanding of the physical processes and selection effects affecting the observed scaling relations. Here we review the recent literature on various scaling relations, focussing on the latest observational measurements and the progress in our understanding of the deviations from self similarity.

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“…The corresponding uncertainties were given by differentiation of the regularised density profile at each point corresponding to the effective radius of the deconvolved temperature profile. Uncertainties on each X-ray mass point were calculated using a Monte Carlo approach based on that of Pratt & Arnaud (2003), where a random temperature was generated at each radius at which the temperature profile is measured, and a cubic spline used to compute the derivative. We only kept random profiles that were physical, meaning that the mass profile must increase monotonically with radius and the randomised temperature profiles must be convectively stable, assuming the standard Schwarzschild criterion in the abscence of strong heat conductivity, i.e., dln T/dln n e < 2/3.…”

Section: X-ray Mass Profilementioning

confidence: 99%

Planckintermediate results

Ade¹,

Aghanim²,

Arnaud³

et al. 2013

A&A

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We examine the relation between the galaxy cluster mass M and Sunyaev-Zeldovich (SZ) effect signal D 2 A Y 500 for a sample of 19 objects for which weak lensing (WL) mass measurements obtained from Subaru Telescope data are available in the literature. Hydrostatic X-ray masses are derived from XMM-Newton archive data, and the SZ effect signal is measured from Planck all-sky survey data. We find an M WL −D 2 A Y 500 relation that is consistent in slope and normalisation with previous determinations using weak lensing masses; however, there is a normalisation offset with respect to previous measures based on hydrostatic X-ray mass-proxy relations. We verify that our SZ effect measurements are in excellent agreement with previous determinations from Planck data. For the present sample, the hydrostatic X-ray masses at R 500 are on average ∼20 percent larger than the corresponding weak lensing masses, which is contrary to expectations. We show that the mass discrepancy is driven by a difference in mass concentration as measured by the two methods and, for the present sample, that the mass discrepancy and difference in mass concentration are especially large for disturbed systems. The mass discrepancy is also linked to the offset in centres used by the X-ray and weak lensing analyses, which again is most important in disturbed systems. We outline several approaches that are needed to help achieve convergence in cluster mass measurement with X-ray and weak lensing observations.

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Entropy scaling in galaxy clusters: Insights from anXMM-Newtonobservation of the poor cluster A1983

Cited by 96 publications

References 68 publications

Searching for the missing baryons in clusters

Searching for the missing baryons in clusters

Scaling Relations for Galaxy Clusters: Properties and Evolution

Planckintermediate results

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