Cosmological constraints from the X-ray gas mass fraction in relaxed lensing clusters observed with Chandra

Allen, S. W.; Schmidt, Robert W.; Fabian, A. C.

doi:10.1046/j.1365-8711.2002.05601.x

Cited by 275 publications

(306 citation statements)

References 32 publications

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“…The measurement of the baryon mass fraction in nearby galaxy clusters has been recognised for several years to be a powerful method to measure the cosmological density parameter (e.g., Mohr et al 1999), while its redshift evolution provides constraints on the dark energy content of the Universe (e.g., Allen et al 2002;Ettori et al 2003, and references therein). Since diffuse gas dominates the baryon budget of clusters, a precise measurement of the ICM total mass represents a fundamental step in the application of this cosmological test.…”

Section: The Gas Mass Fractionmentioning

confidence: 99%

Thermodynamical Properties of the ICM from Hydrodynamical Simulations

et al. 2008

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Modern hydrodynamical simulations offer nowadays a powerful means to trace the evolution of the X-ray properties of the intra-cluster medium (ICM) during the cosmological history of the hierarchical build up of galaxy clusters. In this paper we review the current status of these simulations and how their predictions fare in reproducing the most recent X-ray observations of clusters. After briefly discussing the shortcomings of the self-similar model, based on assuming that gravity only drives the evolution of the ICM, we discuss how the processes of gas cooling and non-gravitational heating are expected to bring model predictions into better agreement with observational data. We then present results from the hydrodynamical simulations, performed by different groups, and how they compare with observational data. As terms of comparison, we use X-ray scaling relations between mass, luminosity, temperature and pressure, as well as the profiles of temperature and entropy. The results of this comparison can be summarised as follows: (a) which include gas cooling, star formation and supernova feedback, are generally successful in reproducing the X-ray properties of the ICM outside the core regions; (b) simulations generally fail in reproducing the observed "cool core" structure, in that they have serious difficulties in regulating overcooling, thereby producing steep negative central temperature profiles. This discrepancy calls for the need of introducing other physical processes, such as energy feedback from active galactic nuclei, which should compensate the radiative losses of the gas with high density, low entropy and short cooling time, which is observed to reside in the innermost regions of galaxy clusters.

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Section: The Gas Mass Fractionmentioning

confidence: 99%

Thermodynamical Properties of the ICM from Hydrodynamical Simulations

et al. 2008

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“…In this section we consider a recently proposed test based on the gas mass fraction in galaxy clusters (Allen et al 2002). Both theoretical arguments and numerical simulations predict that the baryonic mass fraction in the largest relaxed galaxy clusters should not depend on the redshift, and should provide an estimate of the cosmological baryonic density parameter Ω b (Eke et al 1998).…”

Section: The Gas Fraction In Clustersmentioning

confidence: 99%

“…Following the procedure described in (Allen et al 2002(Allen et al , 2004, we adopt the SCDM model (i.e., a flat universe with Ω M = 1 and h = 0.5, where h is the Hubble constant in units of 100 km s −1 Mpc −1 ) as a reference cosmology in making the measurements so that the theoretical expectation for the apparent variation of f gas with the redshift is:…”

Section: The Gas Fraction In Clustersmentioning

confidence: 99%

Accelerating universe in scalar tensor models – comparison of theoretical predictions with observations

Demiański

Piedipalumbo

Rubano

et al. 2006

A&A

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Aims. To study the possibility of the appearance of an accelerated universe in scalar tensor cosmological models. Methods. We consider scalar tensor theories of gravity assuming that the scalar field is not minimally coupled with gravity. We use this theory to study evolution of a flat homogeneous and isotropic universe. In this case the dynamical equations can be derived form a point-like Lagrangian. We study the general properties of dynamics of this system and show that for a wide range of initial conditions such models lead in a natural way to an accelerated phase of expansion of the universe. Assuming that the point-like Lagrangian admits a Noether symmetry, we are able to explicitly solve the dynamical equations. Results. We study one particular model and show that its predictions are compatible with observational data, namely the publicly available data on type Ia supernovae, the parameters of large scale structure determined by the 2-degree Field Galaxy Redshift Survey (2dFGRS), the measurements of cosmological distances with the Sunyaev-Zel'dovich effect and the rate of growth of density perturbations. This model produces in a natural way an epoch of accelerated expansion. With an appropriate choice of parameters our model is fully compatible with several observed characteristics of the universe.

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“…Starting from these pioneering works, many studies have followed this approach to constrain the cosmological parameters (White & Fabian 1995;David et al 1995;Ettori & Fabian 1998;Rines et al 1999;Roussel et al 2000;Allen et al 2002;Ettori et al 2003;Castillo-Morales & Schindler 2003;Sadat et al 2005;Allen et al 2008). We present here a revised and updated version of the work discussed in Ettori et al (2003, Paper I).…”

Section: Introductionmentioning

confidence: 99%

The cluster gas mass fraction as a cosmological probe: a revised study

Ettori

Morandi

Tozzi

et al. 2009

A&A

185

237

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Context. We present the analysis of the baryonic content of 52 X-ray luminous galaxy clusters observed with Chandra in the redshift range 0.3-1.273. Aims. Our study aims at resolving the gas mass fraction in these objects to place constraints on the cosmological parameters Ω m , Ω Λ and the ratio between the pressure and density of the dark energy, w. Methods. We deproject the X-ray surface brightness profiles to recover the gas mass profiles and fit a single thermal component to the spectrum extracted from a region around the cluster that maximizes the signal-to-noise ratios in the observation. The measured values of the gas temperature are used to evaluate the temperature profile with a given functional form and to estimate the total gravitating mass in combination with the gas density profiles. These measured quantities are then used to statistically estimate the gas fraction and the fraction of mass in stars. By assuming that galaxy clusters are representative of the cosmic baryon budget, the distribution of the cluster baryon fraction in the hottest (T gas > 4 keV) systems as a function of redshift is used to constrain the cosmological parameters. We discuss how our constraints are affected by several systematic effects, namely the isothermality, the assumed baryon fraction in stars, the depletion parameter and the sample selection. Results. By using only the cluster baryon fraction as a proxy for the cosmological parameters, we obtain that Ω m is very well constrained at the value of 0.35 with a relative statistical uncertainty of 11% (1σ level; w = −1) and a further systematic error of about (−6, +7)%. On the other hand, constraints on Ω Λ (without the prior of flat geometry) and w (using the prior of flat geometry) are definitely weaker due to the presence of greater statistical and systematic uncertainties (of the order of 40 per cent on Ω Λ and greater than 50 per cent on w). If the WMAP 5-year best-fit results are assumed to fix the cosmological parameters, we limit the contributions expected from non-thermal pressure support and ICM clumpiness to be lower than about 10 per cent, also leaving room to accommodate baryons not accounted for either in the X-ray emitting plasma or in stars of the order of 18 per cent of the total cluster baryon budget. This value is lowered to zero for a no-flat Universe with Ω Λ > 0.7.

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Cosmological constraints from the X-ray gas mass fraction in relaxed lensing clusters observed with Chandra

Cited by 275 publications

References 32 publications

Thermodynamical Properties of the ICM from Hydrodynamical Simulations

Thermodynamical Properties of the ICM from Hydrodynamical Simulations

Accelerating universe in scalar tensor models – comparison of theoretical predictions with observations

The cluster gas mass fraction as a cosmological probe: a revised study

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