The Galaxy Content of SDSS Clusters and Groups

Hansen, S. M.; Sheldon, E.; Koester, Benjamin P.

doi:10.1088/0004-637x/699/2/1333

Cited by 237 publications

(367 citation statements)

References 160 publications

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“…The tangential shear profile yields r 200 ∼ 840 kpc and M 200 ∼ 0.85 × 10 14 M , fully consistent with the predictions made by the cluster sizerichness relation of Hansen et al (2009). From this point of view J0454 is indistinguishable from normal clusters, forming either a rich fossil group or a poor fossil cluster.…”

Section: Discussionsupporting

confidence: 84%

J0454-0309: evidence of a strong lensing fossil group falling into a poor galaxy cluster

Schirmer¹,

Suyu²,

Schrabback

et al. 2010

A&A

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Aims. We have discovered a strong lensing fossil group (J0454) projected near the well-studied cluster MS0451-0305. Using the large amount of available archival data, we compare J0454 to normal groups and clusters. A highly asymmetric image configuration of the strong lens enables us to study the substructure of the system. Methods. We used multicolour Subaru/Suprime-Cam and CFHT/Megaprime imaging, together with Keck spectroscopy to identify member galaxies. A VLT/FORS2 spectrum was taken to determine the redshifts of the brightest elliptical and the lensed arc. Using HST/ACS images, we determined the group's weak lensing signal and modelled the strong lens system. This is the first time that a fossil group is analysed with lensing methods. The X-ray luminosity and temperature were derived from XMM-Newton data. Results. J0454 is located at z = 0.26, with a gap of 2.5 mag between the brightest and second brightest galaxies within half the virial radius. Outside a radius of 1.5 Mpc, we find two filaments extending over 4 Mpc, and within we identify 31 members spectroscopically and 33 via the red sequence with i < 22 mag. (BGG) is inconsistent with the dynamic centre of J0454. It strongly lenses a galaxy at z = 2.1 ± 0.3, and we model the lens with a pseudo-isothermal elliptical mass distribution. A high external shear, and a discrepancy between the Einstein radius and the weak lensing velocity dispersion requires that the BGG must be offset from J0454's dark halo centre by at least 90−130 kpc. The X-ray halo is offset by 24 ± 16 kpc from the BGG, shows no signs of a cooling flow and can be fit by a single β-model. With L X = (1.4 ± 0.2) × 10 43 erg s −1 J0454 falls onto standard cluster scaling relations, but appears cooler (T = 1.1 ± 0.1 keV) than expected (T ∼ 2.0 keV). Taken all together, these data indicate that J0454 consists of two systems, a sparse cluster and an infalling fossil group, where the latter seeds the brightest cluster galaxy. An alternative to the sparse cluster could be a filament projected along the line of sight mimicking a cluster, with galaxies streaming towards the fossil group.

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Section: Discussionsupporting

confidence: 84%

J0454-0309: evidence of a strong lensing fossil group falling into a poor galaxy cluster

Schirmer¹,

Suyu²,

Schrabback

et al. 2010

A&A

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show abstract

“…First, the Skibba & Sheth (2009) model is extended by allowing for a dependence of the colour distribution on halo mass at fixed luminosity Hearin & Watson 2013;Rodríguez-Puebla et al 2013), and we include colour gradients within haloes (Hansen et al 2009;van den Bosch et al 2008), which results in red galaxies having higher number density concentrations than blue galaxies in haloes of a given mass (as measured by Collister & Lahav 2005). We include stellar masses based on the Zibetti et al (2009) Wojtak & Mamon (2013) and account for the fact that galaxies and subhaloes are less concentrated than dark matter (e.g., Hansen et al 2005;Yang et al 2005b, Wojtak & Mamon 2013 by adopting concentration index c gal = cDM/1.5.…”

Section: Halo Occupation Distribution Modelmentioning

confidence: 99%

Galaxy Cluster Mass Reconstruction Project – II. Quantifying scatter and bias using contrasting mock catalogues

Old

Wojtak

Mamon

et al. 2015

Monthly Notices of the Royal Astronomical Society

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This article is the second in a series in which we perform an extensive comparison of various galaxy-based cluster mass estimation techniques that utilise the positions, velocities and colours of galaxies. Our aim is to quantify the scatter, systematic bias and completeness of cluster masses derived from a diverse set of 25 galaxy-based methods using two contrasting mock galaxy catalogues based on a sophisticated halo occupation model and a semi-analytic model. Analysing 968 clusters, we find a wide range in the RMS errors in log M 200c delivered by the different methods (0.18 to 1.08 dex, i.e., a factor of ∼1.5 to 12), with abundance matching and richness methods providing the best results, irrespective of the input model assumptions. In addition, certain methods produce a significant number of catastrophic cases where the mass is under-or over-estimated by a factor greater than 10. Given the steeply falling high-mass end of the cluster mass function, we recommend that richness or abundance matching-based methods are used in conjunction with these methods as a sanity check for studies selecting high mass clusters. We see a stronger correlation of the recovered to input number of galaxies for both catalogues in comparison with the group/cluster mass, however, this does not guarantee that the correct member galaxies are being selected. We do not observe significantly higher scatter for either mock galaxy catalogues. Our results have implications for cosmological analyses that utilise the masses, richnesses, or abundances of clusters, which have different uncertainties when different methods are used.

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“…Quantitatively speaking, the red satellite fraction decreases from ∼ 80 % at projected radius 100 kpc from L * satellite galaxies to ∼ 70 % at about the virial radius (e.g., Hansen et al 2009;Prescott et al 2011). Here we consider only L * halos because they are expected to be the dominant contributor to the Mg II covering fraction from a halo occupation analysis ).…”

Section: Environmental Effectsmentioning

confidence: 99%

Characterizing the chemically enriched circumgalactic medium of ∼38 000 luminous red galaxies in SDSS DR12

Huang

Chen

Johnson

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We report a definitive detection of chemically-enriched cool gas around massive, quiescent galaxies at z ≈ 0.4 − 0.7. The result is based on a survey of 37621 luminous red galaxy (LRG)-QSO pairs in SDSS DR12 with projected distance d < 500 kpc. LRGs at d < 50 kpc, provides important insights into the origin of the observed chemically-enriched cool gas in LRG halos. We consider different scenarios and conclude that the observed Mg II absorbers around LRGs are best-explained by a combination of cool clouds formed in thermally unstable LRG halos and satellite accretion through filaments.

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The Galaxy Content of SDSS Clusters and Groups

Cited by 237 publications

References 160 publications

J0454-0309: evidence of a strong lensing fossil group falling into a poor galaxy cluster

J0454-0309: evidence of a strong lensing fossil group falling into a poor galaxy cluster

Galaxy Cluster Mass Reconstruction Project – II. Quantifying scatter and bias using contrasting mock catalogues

Characterizing the chemically enriched circumgalactic medium of ∼38 000 luminous red galaxies in SDSS DR12

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