EstimatingfNLandgNLfrom massive high-redshift galaxy clusters

Enqvist, Kari; Hotchkiss, Shaun; Taanila, Olli

doi:10.1088/1475-7516/2011/04/017

Cited by 36 publications

(67 citation statements)

References 88 publications

(239 reference statements)

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“…VI. In the range R s ∼ 1 − 10 h −1 Mpc, the scale dependence of S (3) s,loc is accurately reproduced by an empirical power-law relation, S for our fiducial cosmology (this agrees with the findings of [56,57]). Hence, the second term in Eq.…”

Section: Local Non-gaussianitysupporting

confidence: 86%

Non-Gaussian Halo Bias Re-examined: Mass-dependent Amplitude from the Peak-Background Split and Thresholding

Desjacques

Jeong

2011

Phys. Rev. D

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Recent results of N-body simulations have shown that current theoretical models are not able to correctly predict the amplitude of the scale-dependent halo bias induced by primordial nonGaussianity, for models going beyond the simplest, local quadratic case. Motivated by these discrepancies, we carefully examine three theoretical approaches based on (1) the statistics of thresholded regions, (2) a peak-background split method based on separation of scales, and (3) a peak-background split method using the conditional mass function. We first demonstrate that the statistics of thresholded regions, which is shown to be equivalent at leading order to a local bias expansion, cannot explain the mass-dependent deviation between theory and N-body simulations. In the two formulations of the peak-background split on the other hand, we identify an important, but previously overlooked, correction to the non-Gaussian bias that strongly depends on halo mass. This new term is in general significant for any primordial non-Gaussianity going beyond the simplest local fNL model. In a separate paper [1], we compare these new theoretical predictions with N-body simulations, showing good agreement for all simulated types of non-Gaussianity.PACS numbers: 98.80.Cq, 95.36.+x

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Section: Local Non-gaussianitysupporting

confidence: 86%

Non-Gaussian Halo Bias Re-examined: Mass-dependent Amplitude from the Peak-Background Split and Thresholding

Desjacques

Jeong

2011

Phys. Rev. D

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“…When f NL = 580 we note that each cluster is more likely to exist, and the combined probability = 1 (for our mass function), which suggests that this model is a better description to the observed Universe [although see, 13, for a discussion of the validity of the chosen mass function].…”

Section: All Clustersmentioning

confidence: 89%

Implications of multiple high-redshift galaxy clusters

2011

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To date, 14 high-redshift (z > 1.0) galaxy clusters with mass measurements have been observed, spectroscopically confirmed and are reported in the literature. These objects should be exceedingly rare in the standard ΛCDM model. We conservatively approximate the selection functions of these clusters' parent surveys, and quantify the tension between the abundances of massive clusters as predicted by the standard ΛCDM model and the observed ones. We alleviate the tension considering non-Gaussian primordial perturbations of the local type, characterized by the parameter fNL and derive constraints on fNL arising from the mere existence of these clusters. At the 95% confidence level, fNL > 467 with cosmological parameters fixed to their most likely WMAP5 values, or fNL > ∼ 123 (at 95% confidence) if we marginalize over WMAP5 parameters priors. In combination with fNL constraints from Cosmic Microwave Background and halo bias, this determination implies a scaledependence of fNL at 3 σ. Given the assumptions made in the analysis, we expect any future improvements to the modeling of the non-Gaussian mass function, survey volumes, or selection functions to increase the significance of fNL > 0 found here. In order to reconcile these massive, high-z clusters with an fNL = 0, their masses would need to be systematically lowered by 1.5 σ or the σ8 parameter should be ∼ 3 σ higher than CMB (and large-scale structure) constraints. The existence of these objects is a puzzle: it either represents a challenge to the ΛCDM paradigme or it is an indication that the mass estimates of clusters is dramatically more uncertain than we think.

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“…We see that the D08 mass function results in a marginal error σ fNL ≃ 300, which can be compared with the error quoted by W11 which is 450. This shows that our analysis works; the fact that our marginal error for D08 is smaller, is 5 We note that in contrast to W11, earlier analyses [15,16] showed a significant tension with standard ΛCDM. It would then seem to be more interesting to perform our analysis on the set of clusters used in these analyses rather than W11.…”

Section: Constraints On Fnlmentioning

confidence: 58%

“…the Matarrese et al (MVJ) [19] result becomes imaginary for f NL > 0 when ǫν ∼ 3). This would be an academic issue, were it not for the fact that the current quality of data requires predictions of number counts at combinations of (f NL , M, z) values which lie squarely in the |ǫν| > 1 corner [16]. To see this, note that e.g.…”

Section: Number Counts In the Extreme Tailmentioning

confidence: 99%

“…[10][11][12]). There have been several recent attempts at using massive high-redshift clusters to constrain primordial NG [13][14][15][16][17]. Williamson et al (W11) [17] analysed a subset of the clusters detected by the South Pole Telescope (SPT), using a likelihood analysis which carefully accounts for issues such as the survey selection function.…”

Section: Introductionmentioning

confidence: 99%

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Extreme tail of the non-Gaussian mass function

2011

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Number counts of massive high-redshift clusters provide a window to study primordial nonGaussianity. The current quality of data, however, forces the statistical analysis to probe a region of parameter space -the extreme tail of the mass function -which is neither accessible in any of the currently available theoretical prescriptions for calculating the mass function, nor calibrated in N -body simulations. In this work we present a new analytical prescription for calculating a "resummed" non-Gaussian halo mass function, which is constructed to remain stable in the extreme tail. We show that the prescription works well in the parameter regime that has been currently explored in simulations. We then use Fisher matrix techniques to compare our prescription with an extrapolated fit to N -body simulations, which has recently been used to obtain constraints from data collected by the South Pole Telecope. We show that for the current data, both prescriptions would lead to statistically consistent constraints. As the data improve, however, there is a possibility of introducing a statistically significant bias in the constraints due to the choice of prescription, especially if non-Gaussianity is scale dependent and becomes relatively large on cluster scales. It would then be necessary to test the accuracy of the prescriptions in N -body simulations that can probe clusters with high masses and redshifts in the presence of large non-Gaussianity.

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Estimatingf_NLandg_NLfrom massive high-redshift galaxy clusters

Cited by 36 publications

References 88 publications

Non-Gaussian Halo Bias Re-examined: Mass-dependent Amplitude from the Peak-Background Split and Thresholding

Non-Gaussian Halo Bias Re-examined: Mass-dependent Amplitude from the Peak-Background Split and Thresholding

Implications of multiple high-redshift galaxy clusters

Extreme tail of the non-Gaussian mass function

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