Optimizing observational strategy for future<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>f</mml:mi><mml:mi>gas</mml:mi></mml:msub></mml:math>constraints

Galli, S.; Bartlett, J. G.; Melchiorri, A.

doi:10.1103/physrevd.86.043516

Cited by 2 publications

(3 citation statements)

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“…The number density tail is very sensitive to changes in cosmological parameters (as demonstrated by recent measurements, e.g., by Allen et al 2008;Vikhlinin et al 2009b) including the dynamical characteristics of dark energy, primordial non-Gaussianity, and the theory of gravity. Hence, future large surveys of clusters (in the optical, X-ray, and microwave/radio/sub-mm wavelengths) with substantially increased statistics and resolution can potentially provide a gold mine for fundamental cosmology (e.g., Battye & Weller 2003;Hu 2003;Majumdar & Mohr 2003, 2004Khedekar et al 2010;Galli et al 2012). However, this is only possible if systematics associated with cluster mass calibrations and our incomplete knowledge of the physics of the intracluster medium (ICM) can be understood and controlled.…”

Section: Introductionmentioning

confidence: 99%

On the Cluster Physics of Sunyaev-Zel'dovich and X-Ray Surveys. Iii. Measurement Biases and Cosmological Evolution of Gas and Stellar Mass Fractions

Battaglia

Bond

Pfrommer

et al. 2013

ApJ

103

128

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Gas masses tightly correlate with the virial masses of galaxy clusters, allowing for a precise determination of cosmological parameters by means of large-scale X-ray surveys. However, the gas mass fractions ( f gas ) at the virial radius (R 200 ) derived from recent Suzaku observations of several groups are considerably larger than the cosmic mean, calling into question the accuracy of estimates of cosmological parameters. Here, we use a large suite of cosmological hydrodynamical simulations to study measurement biases of f gas . We employ different variants of simulated physics, including radiative gas physics, star formation, and thermal feedback by active galactic nuclei, which we show is able to arrest overcooling and to result in constant stellar mass fractions for redshifts z < 1. This implies that the stellar and dark matter masses increase at the same rate, which is realized if most of the stellar mass is already in place by the time it assembles in the cluster halo-in agreement with observations. Computing the mass profiles in 48 angular cones, whose footprints partition the sphere, we find anisotropic gas and total mass distributions that imply an angular variance of f gas at the level of 30%. This anisotropic distribution originates from the recent formation epoch of clusters and from the strong internal baryon-to-dark-matter density bias. In the most extreme cones, f gas can be biased high by a factor of two at R 200 in massive clusters (M 200 ∼ 10 15 M ⊙ ), thereby providing a potential explanation for high f gas measurements by Suzaku. While projection lowers this factor, there are other measurement biases that may (partially) compensate. We find that at R 200 , f gas is biased high by 20% when assuming hydrostatic equilibrium masses, i.e., neglecting the kinetic pressure, and by another ∼ 10 − 20% due to the presence of density clumping (depending on mass and dynamical state). At larger radii, both measurement biases increase dramatically. While the cluster sample variance of the true f gas decreases to a level of 5% at R 200 , the sample variance that includes both measurement biases remains fairly constant at the level of 10 − 20% (depending on dynamical state). At the high-mass end (M 500 > 2 × 10 14 M ⊙ ), the true f gas within R 500 shows a constant redshift evolution. While this result is in principle encouraging for using gas masses to derive cosmological parameters, careful X-ray mocks are needed to control those various measurement biases.

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Section: Introductionmentioning

confidence: 99%

On the Cluster Physics of Sunyaev-Zel'dovich and X-Ray Surveys. Iii. Measurement Biases and Cosmological Evolution of Gas and Stellar Mass Fractions

Battaglia

Bond

Pfrommer

et al. 2013

ApJ

103

128

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“…In fact, it implies that exponents of these power-law relations should have particular values (Kaiser 1986). Deviations from these average relations indicate the importance of other factors, such as accretion history or shape of the initial density peaks (Gao & White 2007;Dalal et al 2008). Massive systems like clusters are rare and isolated, and present a more homogeneous population than lower mass systems, such as galaxies.…”

Section: Approachmentioning

confidence: 99%

“…A 5 Ms program would then yield ∼100 massive clusters with measured temperatures and, in the best cases, gas mass profiles in the relatively unexplored redshift range 0.5 < z < 1. This follow-up would help calibrate the SZ-mass relation in this redshift range and extend the reach of cluster gas mass fraction measurements and dark energy studies (e.g., Galli et al 2012). Such a project falls naturally under the category of Very Large Programs envisaged as legacy projects for XMM-Newton after 2010.…”

Section: Introductionmentioning

confidence: 99%

ThePlanckSZ Cluster Catalog: expected X-ray properties

Chamballu¹,

Bartlett²,

Melin³

2012

A&A

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Surveys based on the Sunyaev-Zel'dovich (SZ) effect provide a fresh view of the galaxy cluster population, one that is complementary to X-ray surveys. To better understand the relation between these two kinds of survey, we construct an empirical cluster model using scaling relations constrained by current X-ray and SZ data. We apply our model to predict the X-ray properties of the Planck SZ Cluster Catalog (PCC) and compare them to existing X-ray cluster catalogs. We find that Planck should significantly extend the depth of the previous all-sky cluster survey, performed in the early 1990s by the ROSAT satellite, and should be particularly effective at finding hot, massive clusters (T > 6 keV) out to redshift unity. These are rare objects, and our findings suggest that Planck could increase the observational sample at z > 0.6 by an order of magnitude. This would open the way for detailed studies of massive clusters out to these higher redshifts. Specifically, we find that the majority of newly-detected Planck clusters should have X-ray fluxes 10 −13 erg/s/cm 2 < f X [0.5−2 keV] < 10 −12 erg/s/cm 2 , i.e., distributed over the decade in flux just below the ROSAT All Sky Survey limit. This is sufficiently bright for extensive X-ray follow-up campaigns. Once Planck finds these objects, XMM-Newton and Chandra could measure temperatures to 10% for a sample of ∼100 clusters in the range 0.5 < z < 1, a valuable increase in the number of massive clusters studied over this range.

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Optimizing observational strategy for futurefgasconstraints

Cited by 2 publications

References 50 publications

On the Cluster Physics of Sunyaev-Zel'dovich and X-Ray Surveys. Iii. Measurement Biases and Cosmological Evolution of Gas and Stellar Mass Fractions

On the Cluster Physics of Sunyaev-Zel'dovich and X-Ray Surveys. Iii. Measurement Biases and Cosmological Evolution of Gas and Stellar Mass Fractions

ThePlanckSZ Cluster Catalog: expected X-ray properties

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