Mass distribution in nearby Abell clusters

Łokas, Ewa L.; Wojtak, Radosław; Gottlöber, Stefan; Mamon, G. A.; Prada, Francisco

doi:10.1111/j.1365-2966.2006.10151.x

Cited by 70 publications

(115 citation statements)

References 41 publications

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“…Kinematical modelers attempt to throw out the high-velocity interlopers by identifying this gap by eye (Kent & Gunn 1982;Łokas & Mamon 2003) or automatically (Fadda et al 1996) or by rejecting 3σ outliers, either using a global criterion (Yahil & Vidal 1977) or a local one (e.g. Łokas et al 2006;Wojtak & Łokas 2010). Interestingly, the 3σ v criterion was first motivated on statistical grounds, but the v 2.0 v v inflection point one sees in the plots of Fig.…”

Section: Global Statisticsmentioning

confidence: 99%

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The universal distribution of halo interlopers in projected phase space

Mamon

Biviano

Murante

2010

A&A

Self Cite

106

149

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When clusters of galaxies are viewed in projection, one cannot avoid picking up a fraction of foreground/background interlopers, that lie within the virial cone, but outside the virial sphere. Structural and kinematic deprojection equations are known for the academic case of a static Universe, but not for the real case of an expanding Universe, where the Hubble flow (HF) stretches the line-of-sight distribution of velocities. Using 93 mock relaxed clusters, built from the dark matter (DM) particles of a hydrodynamical cosmological simulation, we quantify the distribution of interlopers in projected phase space (PPS), as well as the biases in the radial and kinematical structure of clusters produced by the HF. The stacked mock clusters are well fit by an m = 5 Einasto DM density profile (but only out to 1.5 virial radii), with velocity anisotropy (VA) close to the Mamon-Łokas model with characteristic radius equal to that of density slope −2. The surface density of interlopers is nearly flat out to the virial radius, while their velocity distribution shows a dominant Gaussian cluster-outskirts component and a flat field component. This distribution of interlopers in PPS is nearly universal, showing only small trends with cluster mass, and is quantified. A local κ = 2.7 sigma velocity cut is found to return the line-ofsight velocity dispersion profile (LOSVDP) expected from the NFW density and VA profiles measured in three dimensions. The HF causes a shallower outer LOSVDP that cannot be well matched by the Einasto model for any value of κ. After this velocity cut, which removes 1 interloper out of 6, interlopers still account for 23 ± 1% of all DM particles with projected radii within the virial radius (surprisingly very similar to the observed fraction of cluster galaxies lying off the Red Sequence) and over 60% between 0.8 and 1 virial radius. The HF causes the best-fit projected NFW or m = 5 Einasto model to the stacked cluster to underestimate the true concentration measured in 3D by 6 ± 6% (16 ± 7%) after (before) the velocity cut. These biases in concentration are reduced by over a factor two once a constant background is included in the fit. The VA profile recovered from the measured LOSVDP by assuming the correct mass profile recovers fairly well the VA measured in 3D, with a slight, marginally significant, bias towards more radial orbits in the outer regions. These small biases in the concentration and VA of the galaxy system are overshadowed by important cluster-to-cluster fluctuations caused by cosmic variance and by the strong inefficiency caused by the limited numbers of observed galaxies in clusters. An appendix provides an analytical approximation to the surface density, projected mass and tangential shear profiles of the Einasto model. Another derives the expressions for the surface density and mass profiles of the NFW model projected on the sphere (for future kinematic modeling).

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Section: Global Statisticsmentioning

confidence: 99%

“…We remove the interlopers of the stacked cluster proceeding along similar lines as Łokas et al (2006Łokas et al ( , see also Wojtak et al 2007, by clipping the velocities beyond κ times the local lineof-sight velocity dispersion. We assume that our stacked cluster has an NFW profile (Eq.…”

Section: Interloper Removalmentioning

confidence: 99%

The universal distribution of halo interlopers in projected phase space

Mamon

Biviano

Murante

2010

A&A

Self Cite

106

149

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“…Girardi et al 1998;Lokas & Mamon 2003;Lokas et al 2006;Mamon & Boué 2010;Falco et al 2014). Clusters of galaxies are a very important cosmological probe.…”

Section: Motivationmentioning

confidence: 99%

Weak lensing reconstructions in 2D and 3D: implications for cluster studies

Leonard

Lanusse

Starck

2015

Monthly Notices of the Royal Astronomical Society

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We compare the efficiency with which 2D and 3D weak lensing mass mapping techniques are able to detect clusters of galaxies using two state-of-the-art mass reconstruction techniques: MRLens in 2D and GLIMPSE in 3D. We simulate otherwise-empty cluster fields for 96 different virial mass-redshift combinations spanning the ranges 3 × 10 13 h −1 M ⊙ M vir 10 15 h −1 M ⊙ and 0.05 z cl 0.75, and for each generate 1000 realisations of noisy shear data in 2D and 3D. For each field, we then compute the cluster (false) detection rate as the mean number of cluster (false) detections per reconstruction over the sample of 1000 reconstructions. We show that both MRLens and GLIMPSE are effective tools for the detection of clusters from weak lensing measurements, and provide comparable quality reconstructions at low redshift. At high redshift, GLIMPSE reconstructions offer increased sensitivity in the detection of clusters, yielding cluster detection rates up to a factor of ∼ 10× that seen in 2D reconstructions using MRLens. We conclude that 3D mass mapping techniques are more efficient for the detection of clusters of galaxies in weak lensing surveys than 2D methods, particularly since 3D reconstructions yield unbiased estimators of both the mass and redshift of the detected clusters directly.

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“…Moore's law is roughly reflected also in the evolution of the ART code: It's very first version could handle 32 3 particles, whereas 20 years later the MPI version handles 1024 3 particles, a factor of 2 15 increase. Moore's law predicts a factor of 2 13 .…”

Section: Historymentioning

confidence: 99%

“…Using indirect approaches, which are applied to the data stacked from many objects, we reproduced the properties of composite clusters and estimated the probability of finding an interloper as a function of distance from the object center. We used mock catalogs extracted from the same simulation to test a new method with which we studied the mass distribution in six nearby (z < 0.06) relaxed Abell clusters of galaxies [15]. Based on this cosmological N-body simulation we are able to interpret the complex velocity distribution of galaxies in galaxy cluster Abell 1689 [14].…”

Section: Recent Simulations Run With the Art Codementioning

confidence: 99%

The ART of Cosmological Simulations

Gottlöber

Klypin

High Performance Computing in Science and Engineering, Garching/Munich 2007

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We describe the basic ideas of MPI parallelization of the N-body Adaptive Refinement Tree (ART) code. The code uses self-adaptive domain decomposition where boundaries of the domains (parallelepipeds) constantly move -with many degrees of freedom -in the search of the minimum of CPU time. The actual CPU time spent by each MPI task on a previous time-step is used to adjust boundaries for the next time-step. For a typical decomposition of 5 3 domains, the number of possible changes in boundaries is 3 84 ≈ 10 40 . We describe two algorithms of finding minimum of CPU time for configurations with a large number of domains. Each MPI task in our code solves the N-body problem where the large-scale distribution of matter outside of the boundaries of a domain is represented by relatively few temporary large particles created by other domains. At the beginning of a zerolevel time-step, domains create and exchange large particles. Then each domain advances all its particles for many small time-steps. At the end of the large step, the domains decide where to place new boundaries and re-distribute particles. The scheme requires little communications between processors and is very efficient for large cosmological simulations.

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Mass distribution in nearby Abell clusters

Cited by 70 publications

References 41 publications

The universal distribution of halo interlopers in projected phase space

The universal distribution of halo interlopers in projected phase space

Weak lensing reconstructions in 2D and 3D: implications for cluster studies

The ART of Cosmological Simulations

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