The ESO Nearby Abell Cluster Survey. XII. The Mass and Mass‐to‐Light Ratio Profiles of Rich Clusters

Katgert, P.; Biviano, A.; Mazure, A.

doi:10.1086/380118

Cited by 117 publications

(192 citation statements)

References 101 publications

(197 reference statements)

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“…The best fit density profiles are indistinguishable beyond 0.03 r v , and the outer mass profiles are very close to the infall estimates of Geller, Diaferio & Kurtz (1999). The density profiles are 50% more concentrated than in structures of comparable mass within Katgert et al 2004), as 1) we have, for a single cluster, a larger sample of galaxies, which, given their early morphological type, should be in dynamical equilibrium in the cluster potential; 2) we remove pairs from the computation of the velocity moments; 3) we include kurtosis in the analysis; 4) we model the dark matter distribution using a generalized formula inspired by the results of cosmological N -body simulations; 5) we include hot gas.…”

Section: Kinematic Analysis Of the Coma Clustersupporting

confidence: 62%

Breaking the mass/anisotropy degeneracy in the Coma cluster

Mamon¹,

Łokas²,

Sanchís³

2004

IAU

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Abstract. We provide the first direct lifting of the mass/anisotropy degeneracy for a cluster of galaxies, by jointly fitting the line of sight velocity dispersion and kurtosis profiles of the Coma cluster, assuming an NFW tracer density profile, a generalized-NFW dark matter profile and a constant anisotropy profile. We find that the orbits in Coma must be quasi-isotropic, and find a mass consistent with previous analyses, but a concentration parameter 50% higher than expected in cosmological N -body simulations. We then test the accuracy of our method on realistic non-spherical systems with substructure and streaming motions, by applying it to the ten most massive structures in a cosmological N -body simulation. We find that our method yields fairly accurate results on average (within 20%), although with a wide variation (factor 1.7 at 1 σ) for the concentration parameter, with decreased accuracy and efficiency when the projected mean velocity is not constant with radius.

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Section: Kinematic Analysis Of the Coma Clustersupporting

confidence: 62%

Breaking the mass/anisotropy degeneracy in the Coma cluster

Mamon¹,

Łokas²,

Sanchís³

2004

IAU

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“…Stacked cluster samples have been used successfully in several analyses of the properties of clusters (e.g. Moss & Dickens 1977;Biviano et al 1992;Carlberg et al 1997a;van der Marel et al 2000;Katgert et al 2004;Rines et al 2003). The validity of this approach is supported by the results of cosmological numerical simulations that predict cosmological halos to be characterized by the same, universal mass density profile (Navarro et al 1997).…”

Section: The Construction Of the Stacked Cluster Samplesmentioning

confidence: 98%

“…As a reference low-z (nearby) sample of clusters, we use the 59 ENACS clusters studied in detail by Biviano et al (2002), , and Katgert et al (2004). A full description of the ENACS can be found in Katgert et al (1996Katgert et al ( , 1998.…”

Section: Two Data-setsmentioning

confidence: 99%

“…if at a given radius R n,m , there are m clusters that have not been sampled out to that radius, their contributions at radii R n > R n,m is accounted for by applying a correction factor 1/(1 − m i=1 f i ) to the total galaxy counts in the stacked cluster, where f i is the fraction of galaxies contributed to the total sample by cluster i in the radial range where the cluster is sampled. The method is similar to the one described in Merrifield & Kent (1989) and has been applied to the ENACS sample in Biviano et al (2002) and Katgert et al (2004).…”

Section: The Construction Of the Stacked Cluster Samplesmentioning

confidence: 99%

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The orbital velocity anisotropy of cluster galaxies: evolution

Biviano

Poggianti

2009

A&A

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Context. In nearby clusters early-type galaxies follow isotropic orbits. The orbits of late-type galaxies are instead characterized by slightly radial anisotropy. Little is known about the orbits of the different populations of cluster galaxies at redshift z > 0.3. Aims. We investigate the redshift evolution of the orbits of cluster galaxies. Methods. We use two samples of galaxy clusters spanning similar (evolutionary corrected) mass ranges at different redshifts. The sample of low-redshift (z ∼ 0.0−0.1) clusters is extracted from the ESO Nearby Abell Cluster Survey (ENACS) catalog. The sample of high-redshift (z ∼ 0.4−0.8) clusters is mostly made of clusters from the ESO Distant Cluster Survey (EDisCS). For each of these samples, we solve the Jeans equation for hydrostatic equilibrium separately for two cluster galaxy populations, characterized by the presence and, respectively, absence of emission-lines in their spectra ("ELGs" and "nELGs" hereafter). Using two tracers of the gravitational potential allows to partially break the mass-anisotropy degeneracy which plagues these kinds of analyses. Results. We confirm earlier results for the nearby cluster sample. The mass profile is well fitted by a Navarro, Frenk & White (NFW) profile with concentration c = 4. The mass profile of the distant cluster sample is also well fitted by a NFW profile, but with a slightly lower concentration, as predicted by cosmological simulations of cluster-sized halos. While the mass density profile becomes less concentrated with redshift, the number density profile of nELGs becomes more concentrated with redshift. In nearby clusters, the velocity anisotropy profile of nELGs is close to isotropic, while that of ELGs is increasingly radial with clustercentric radius. In distant clusters the projected phase-space distributions of both nELGs and ELGs are best-fitted by models with radial velocity anisotropy. Conclusions. No significant evolution is detected for the orbits of ELGs, while the orbits of nELGs evolve from radial to isotropic with time. We speculate that this evolution may be driven by the secular mass growth of galaxy clusters during their fast accretion phase. Cluster mass density profiles and their evolution with redshift are consistent with predictions for cluster-sized halos in Λ Cold Dark Matter cosmological simulations. The evolution of the nELG number density profile is opposite to that of the mass density profile, becoming less concentrated with time, probably a result of the transformation of ELGs into nELGs.

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“…where r −2 is the radius of density slope −2, in number (Lin et al 2004), luminosity (Łokas & Mamon 2003) and mass Biviano & Girardi 2003;Katgert et al 2004), with a concentration, c = r v /r −2 , of 3 to 5. For isotropic NFW models, the aperture velocity dispersion is (Appendix A of Mauduit & Mamon 2007) σ v = η v v , where η 0.62 (weakly dependent on concentration), and Eq.…”

Section: Introductionmentioning

confidence: 99%

The universal distribution of halo interlopers in projected phase space

Mamon

Biviano

Murante

2010

A&A

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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The ESO Nearby Abell Cluster Survey. XII. The Mass and Mass‐to‐Light Ratio Profiles of Rich Clusters

Cited by 117 publications

References 101 publications

Breaking the mass/anisotropy degeneracy in the Coma cluster

Breaking the mass/anisotropy degeneracy in the Coma cluster

The orbital velocity anisotropy of cluster galaxies: evolution

The universal distribution of halo interlopers in projected phase space

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