Clustering of galaxies in a hierarchical universe -- III. Mock redshift surveys

Diaferio, Antonaldo; Kauffmann, Guinevere; Colberg, J. M.; White, Simon D. M.

doi:10.1046/j.1365-8711.1999.02663.x

Cited by 119 publications

(163 citation statements)

References 79 publications

(132 reference statements)

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“…Since they are outside the cluster, their spatial distribution is not as centrally concentrated as that of real cluster member particles, hence they contribute to increase the harmonic mean radius estimate. Diaferio et al (1999) came to essentially the same conclusions.…”

Section: Discussionsupporting

confidence: 52%

“…This causes the harmonic mean radius to be overestimated. Therefore, interlopers cause the overestimate of the harmonic mean radius, and, at the same time, the underestimate of the velocity dispersion, as already noted by C97 and Diaferio et al (1999). Since the strongest of the two effects is the harmonic mean radius overestimate, also the virial mass is overestimated.…”

Section: Projection Effectsmentioning

confidence: 59%

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On the efficiency and reliability of cluster mass estimates based on member galaxies

Biviano¹,

Murante

Borgani

et al. 2006

A&A

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232

353

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Aims. We study the efficiency and reliability of cluster mass estimators that are based on the projected phase-space distribution of galaxies in a cluster region. Methods. We analyse a data-set of 62 clusters extracted from a concordance ΛCDM cosmological hydrodynamical simulation. We consider both dark matter (DM) particles and simulated galaxies as tracers of the clusters gravitational potential. Two cluster mass estimators are considered: the virial mass estimator, corrected for the surface-pressure term, and a mass estimator (that we call M σ ) based entirely on the velocity dispersion estimate of the cluster. In order to simulate observations, galaxies (or DM particles) are first selected in cylinders of given radius (from 0.5 to 1.5h −1 Mpc) and 200h −1 Mpc length. Cluster members are then identified by applying a suitable interloper removal algorithm. Results. The virial mass estimator overestimates the true mass by 10% on average, for sample sizes of > ∼ 60 cluster members. For similar sample sizes, M σ underestimates the true mass by 15%, on average. For smaller sample sizes, the bias of the virial mass estimator substantially increases, while the M σ estimator becomes essentially unbiased. The dispersion of both mass estimates increases by a factor ∼2 as the number of cluster members decreases from ∼400 to ∼20. It is possible to reduce the bias in the virial mass estimates either by removing clusters with significant evidence for subclustering or by selecting early-type galaxies, which substantially reduces the interloper contamination. Early-type galaxies cannot however be used to improve the M σ estimates since their intrinsic velocity distribution is slightly biased relative to that of the DM particles. Radially-dependent incompleteness can drastically affect the virial mass estimates, but leaves the M σ estimates almost unaffected. Other observational effects, like centering and velocity errors and different observational apertures, have little effect on the mass estimates.

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Section: Discussionsupporting

confidence: 52%

Section: Projection Effectsmentioning

confidence: 59%

On the efficiency and reliability of cluster mass estimates based on member galaxies

Biviano¹,

Murante

Borgani

et al. 2006

A&A

Self Cite

232

353

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“…This was first pointed out by Biviano et al (1995) in their study of the Coma cluster LF (see also Thompson & Gregory 1993). The deviation of the cluster LF from a single Schecter function was also found in the clusters extracted from the N-body simulations combined with semi-analytical models analysed by Diaferio et al (1999). They interpreted the LF shape as the effect of the large merger cross-section of the bright and massive central galaxies.…”

Section: Luminosity Function Shape and Cluster Massmentioning

confidence: 60%

RASS-SDSS galaxy cluster survey

Popesso¹,

Biviano

Böhringer

et al. 2006

A&A

135

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Aims. We explore the mass-to-light ratio in galaxy clusters and its relation to the cluster mass. Methods. We study the relations among the optical luminosity (L op ), the cluster mass (M 200 ) and the number of cluster galaxies within r 200 (N gal ) in a sample of 217 galaxy clusters with confirmed 3D overdensity. We correct for projection effect, by determining the galaxy surface number density profile in our cluster sample. This is best fitted by a cored King profile in low and intermediate mass systems. The core radius decreases with cluster mass, and, for the highest mass clusters, the profile is better represented by a generalized King profile or a cuspy Navarro, Frenk & White profile. Results. We find a very tight proportionality between L op and N gal , which, in turn, links the cluster mass-to-light ratio to the Halo Occupation Distribution N gal vs. M 200 . After correcting for projection effects, the slope of the L op −M 200 and N gal −M 200 relations is found to be 0.92 ± 0.03, close, but still significantly less than unity. We show that the non-linearity of these relations cannot be explained by variations of the galaxy luminosity distributions and of the galaxy M/L with the cluster mass. Conclusions. We suggest that the nonlinear relation between number of galaxies and cluster mass reflects an underlying nonlinear relation between number of subhaloes and halo mass.

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“…Galaxy groups were identified via the friends-of-friends algorithm (Ramella et al 1997;Diaferio et al 1999;. For the line-of-sight and transverse linking lengths, we adopted 500 km s −1 and 500 kpc, respectively.…”

Section: Color-radius Relationmentioning

confidence: 99%

The environmental dependence of properties of galaxies around the RDCSJ0910+54 cluster atz = 1.1

Tanaka¹,

Finoguenov²,

Kodama³

et al. 2008

A&A

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We report on the environmental dependence of properties of galaxies around the RDCSJ0910+54 cluster at z = 1.1. We obtained multi-band wide-field images of the cluster with Suprime-Cam and MOIRCS on Subaru and WFCAM on UKIRT. Also, an intensive spectroscopic campaign was carried out using LRIS on Keck and FOCAS on Subaru. We collected 161 spectra with secure redshifts, with which we calibrated a larger sample of photometric redshifts. We discover a possible large-scale structure around the cluster in the form of three clumps of galaxies. Two out of the three newly discovered clumps of galaxies are detected as extended X-ray sources, suggesting that they are bound systems. There seem to be filaments of galaxies in between the clumps. This is potentially one of the largest structures found so far in the z > 1 Universe. We then examined stellar populations of galaxies in the structure. First, we quantified the color-radius relation. Red galaxies have already become the dominant population in the cores of rich clusters at z ∼ 1, and the fraction of red galaxies has not strongly changed since then. The red fraction depends on the richness of clusters in the sense that it is higher in rich clusters than in poor groups. We confirm that this trend is not due to possible biases in photometric redshifts. Next, we examined red sequence galaxies. The luminosity function of red galaxies in rich clusters is consistent with one in local clusters. On the other hand, the luminosity function of red galaxies in poor groups shows a deficit of faint red galaxies. This confirms our earlier findings that galaxies follow an environment-dependent down-sizing evolution. Interestingly, the truncation magnitude of the red sequence appears brighter than found in the RDCS J1252−29 field at z = 1.24. This suggests that there is a large variation in the evolutionary phases of galaxies in groups with similar masses. Further studies of high redshift clusters will be a promising way of addressing the role of nature and nurture effects in shaping the environmental dependence of galaxy properties observed in the local Universe.

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Clustering of galaxies in a hierarchical universe -- III. Mock redshift surveys

Cited by 119 publications

References 79 publications

On the efficiency and reliability of cluster mass estimates based on member galaxies

On the efficiency and reliability of cluster mass estimates based on member galaxies

RASS-SDSS galaxy cluster survey

The environmental dependence of properties of galaxies around the RDCSJ0910+54 cluster atz = 1.1

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