NoSOCS in SDSS

Ribeiro, André; Lopes, P. A. A.; Rembold, Sandro Barboza

doi:10.1051/0004-6361/201220801

Cited by 40 publications

(48 citation statements)

References 105 publications

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“…Specifically, if we split our sample into two redshift bins at z=0.45-which optimally balances the number of bright galaxies in the high and low bins-we see the strong drop in peculiar velocity for bright galaxies in each of the high and low-redshift bins. This same qualitative effect has been observed in lowredshift clusters (Chincarini & Rood 1977;Biviano et al 1992;Mohr et al 1996;Goto 2005;Old et al 2013;Ribeiro et al 2013). Barsanti et al (2016) also recently observed a similar effect in an analysis of galaxy clusters drawn from the literature.…”

Section: Velocity Segregation By Relative Luminositysupporting

confidence: 73%

Velocity Segregation and Systematic Biases in Velocity Dispersion Estimates with the SPT-GMOS Spectroscopic Survey

Bayliss

Zengo

Ruel

et al. 2017

ApJ

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The velocity distribution of galaxies in clusters is not universal; rather, galaxies are segregated according to their spectral type and relative luminosity. We examine the velocity distributions of different populations of galaxies within 89 Sunyaev Zel'dovich (SZ) selected galaxy clusters spanning < < z 0.28 1.08. Our sample is primarily draw from the SPT-GMOS spectroscopic survey, supplemented by additional published spectroscopy, resulting in a final spectroscopic sample of 4148 galaxy spectra-2868 cluster members. The velocity dispersion of starforming cluster galaxies is 17±4% greater than that of passive cluster galaxies, and the velocity dispersion of bright ( * < -m m 0.5) cluster galaxies is 11±4% lower than the velocity dispersion of our total member population. We find good agreement with simulations regarding the shape of the relationship between the measured velocity dispersion and the fraction of passive versus star-forming galaxies used to measure it, but we find a small offset between this relationship as measured in data and simulations, which suggests that our dispersions are systematically low by as much as 3% relative to simulations. We argue that this offset could be interpreted as a measurement of the effective velocity bias that describes the ratio of our observed velocity dispersions and the intrinsic velocity dispersion of dark matter particles in a published simulation result. Measuring velocity bias in this way suggests that large spectroscopic surveys can improve dispersion-based mass-observable scaling relations for cosmology even in the face of velocity biases, by quantifying and ultimately calibrating them out.

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Section: Velocity Segregation By Relative Luminositysupporting

confidence: 73%

Velocity Segregation and Systematic Biases in Velocity Dispersion Estimates with the SPT-GMOS Spectroscopic Survey

Bayliss

Zengo

Ruel

et al. 2017

ApJ

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“…Adami et al (1998) and Ribeiro et al (2013) both found VLS for ellipticals and passive galaxies, but no (or even opposite) effect is reported for galaxies of other types. However, the inspection of Fig.…”

Section: Discussionmentioning

confidence: 90%

Velocity segregation effects in galaxy clusters at 0.4 ≲z≲ 1.5

Barsanti

Girardi

Biviano

et al. 2016

A&A

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Aims. Our study is meant to extend our knowledge of the galaxy color and luminosity segregation in velocity space (VCS and VLS, respectively), to clusters at intermediate and high redshift. Methods. Our sample is a collection of 41 clusters in the 0.4 < ∼ z < ∼ 1.5 redshift range for a total of 4172 galaxies, 1674 of which are member galaxies of the clusters within 2R 200 with photometric or spectroscopic information, as taken from the literature. We perform homogeneous procedures to select cluster members, compute global cluster properties, in particular the line-of-sight (LOS) velocity dispersion σ V , and separate blue from red galaxies. Results. We find evidence of VCS in clusters out to z 0.8 (at the 97−99.99% confidence level, depending on the test), in the sense that the blue galaxy population has a 10−20% larger σ V than the red galaxy population. Poor or no VCS is found in the high-z sample at z ≥ 0.8. For the first time, we detect VLS in non-local clusters and confirm that VLS only affects the very luminous galaxies; brighter galaxies have lower velocities. The threshold magnitude of VLS is ∼m 3 + 0.5, where m 3 is the magnitude of the third brightest cluster galaxy. Current data suggest that the threshold value moves to fainter magnitudes at higher redshift. We also detect (marginal) evidence of VLS for blue galaxies. Conclusions. We conclude that segregation effects can be important tracers of the galaxy evolution and cluster assembly when they are studied up to distant clusters. We also discuss the evidence of VCS at high redshift, which is poor or absent.

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“…Interestingly, in multicomponent clusters, we find that these correlations are still preserved. Indeed, Ribeiro et al (2013) find a decreasing fraction of red galaxies with distance from the centers of both Gaussian and non-Gaussian clusters.…”

Section: Star Formation In Single-and Multi-component Clustersmentioning

confidence: 94%

Star Formation and Substructure in Galaxy Clusters

Cohen

Hickox

Wegner

et al. 2014

ApJ

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We investigate the relationship between star formation (SF) and substructure in a sample of 107 nearby galaxy clusters using data from the Sloan Digital Sky Survey. Several past studies of individual galaxy clusters have suggested that cluster mergers enhance cluster SF, while others find no such relationship. The SF fraction in multi-component clusters (0.228 ± 0.007) is higher than that in single-component clusters (0.175 ± 0.016) for galaxies with M 0.1 r < −20.5. In both single-and multi-component clusters, the fraction of star-forming galaxies increases with clustercentric distance and decreases with local galaxy number density, and multi-component clusters show a higher SF fraction than single-component clusters at almost all clustercentric distances and local densities. Comparing the SF fraction in individual clusters to several statistical measures of substructure, we find weak, but in most cases significant at greater than 2σ , correlations between substructure and SF fraction. These results could indicate that cluster mergers may cause weak but significant SF enhancement in clusters, or unrelaxed clusters exhibit slightly stronger SF due to their less evolved states relative to relaxed clusters.

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NoSOCS in SDSS

Cited by 40 publications

References 105 publications

Velocity Segregation and Systematic Biases in Velocity Dispersion Estimates with the SPT-GMOS Spectroscopic Survey

Velocity Segregation and Systematic Biases in Velocity Dispersion Estimates with the SPT-GMOS Spectroscopic Survey

Velocity segregation effects in galaxy clusters at 0.4 ≲z≲ 1.5

Star Formation and Substructure in Galaxy Clusters

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