On optical mass estimation methods for galaxy groups

Pearson, Richard; Ponman, T. J.; Norberg, Peder; Robotham, Aaron S. G.; Farr, W. M.

doi:10.1093/mnras/stv463

Cited by 20 publications

(22 citation statements)

References 68 publications

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“…Combined with the fact that these measurements were made on shallow survey data, this work suggests that these luminosities are promising mass proxies for future surveys, consistent with previous studies (e.g. Girardi et al 2000;Lin et al 2003Lin et al , 2004Ramella et al 2004;Popesso et al 2005;Mulroy et al 2014;Pearson et al 2015;Ziparo et al 2016). We highlight that the specific luminosity measurements used in this work benefited from highly complete K band limited (roughly stellar mass limited) spectroscopic membership catalogues, and prior radial knowledge from weak-lensing analysis.…”

Section: Conclusion and Implications For Future Surveyssupporting

confidence: 83%

Galaxy cluster luminosities and colours, and their dependence on cluster mass and merger state

Mulroy

McGee

Gillman

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We study a sample of 19 galaxy clusters in the redshift range 0.15 < z < 0.30 with highly complete spectroscopic membership catalogues (to K < K * (z) + 1.5) from the Arizona Cluster Redshift Survey, individual weak-lensing masses and near-infrared data from the Local Cluster Substructure Survey, and optical photometry from the Sloan Digital Sky Survey. We fit the scaling relations between total cluster luminosity in each of six bandpasses (grizJK) and cluster mass, finding cluster luminosity to be a promising mass proxy with low intrinsic scatter σ ln L|M of only ∼10-20 per cent for all relations. At fixed overdensity radius, the intercept increases with wavelength, consistent with an old stellar population. The scatter and slope are consistent across all wavelengths, suggesting that cluster colour is not a function of mass. Comparing colour with indicators of the level of disturbance in the cluster, we find a narrower variety in the cluster colours of 'disturbed' clusters than of 'undisturbed' clusters. This trend is more pronounced with indicators sensitive to the initial stages of a cluster merger, e.g. the Dressler Schectman statistic. We interpret this as possible evidence that the total cluster star formation rate is 'standardized' in mergers, perhaps through a process such as a system-wide shock in the intracluster medium.Key words: gravitational lensing: weak -galaxies: clusters: general -cosmology: observations. I N T RO D U C T I O NThe composition of galaxy clusters is thought to represent that of the whole Universe, and so they offer a window into astrophysics on both cluster and galaxy scales (e.g. Kravtsov & Borgani 2012). Their position at the extreme end of the mass function makes them sensitive to the underlying cosmology and provides a late time estimate of the cosmological parameters, complementary to alternative probes such as the cosmic microwave background and supernovae (e.g. Weinberg et al. 2013).Accurate mass measurements of galaxy clusters are necessary to constrain the mass function, and thus cosmology (e.g. Allen, Evrard & Mantz 2011). Methods to make such measurements include: dynamical, which measure the depth of the potential well of the clusters using the velocities of the galaxies; hydrostatic, which E-mail: smulroy@star.sr.bham.ac.uk assume that the gas pressure is balanced by the gravitational attraction; and gravitational weak lensing, which measure the distortion of the light distribution from distant galaxies by the gravitational potential of the cluster. While these methods each have different biases that require further exploration, well-constrained direct individual mass measurements require deep observations and extensive analysis that is not easily extended to very large samples. This motivates research into well-calibrated scaling relations between easily measured 'mass proxies' and cluster mass. The preferable scaling relation is one with minimal intrinsic scatter between observable and mass, and an observable that is easily obtainable from survey data.Potent...

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Section: Conclusion and Implications For Future Surveyssupporting

confidence: 83%

Galaxy cluster luminosities and colours, and their dependence on cluster mass and merger state

Mulroy

McGee

Gillman

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…By further assuming that the group radius is proportional to the velocity dispersion (Carlberg et al 1997), one finds that M scales with σ 3 . It is important to realize, that even if the virial theorem is well established, proxies to the group velocity dispersion (and radius) depends on the survey properties, such that the scaling relation depends also on the group selection technique and definitions choice of observational proxies to r and σ (Old et al 2014;Pearson et al 2015). To estimate the group masses, we use the relation 11 log(M500/(10 14 M )) = α log((H0/H(z)) × (σ/σ0) 3 ) + β, with (α, β, σ0)=(0.94, 0.39, 794.32 km s −1 ) (Pearson et al 2015).…”

Section: Appendix C: Virial Masses Of the Groupsmentioning

confidence: 99%

H0LiCOW – II. Spectroscopic survey and galaxy-group identification of the strong gravitational lens system HE 0435−1223

Sluse¹,

Sonnenfeld

Rumbaugh

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Galaxies located in the environment or on the line of sight towards gravitational lenses can significantly affect lensing observables, and can lead to systematic errors on the measurement of H 0 from the time-delay technique. We present the results of a systematic spectroscopic identification of the galaxies in the field of view of the lensed quasar HE 0435−1223 using the W. M. Keck, Gemini and ESO-Very Large telescopes. Our new catalog triples the number of known galaxy redshifts in the direct vicinity of the lens, expanding to 102 the number of measured redshifts for galaxies separated by less than 3 from the lens. We complement our catalog with literature data to gather redshifts up to 15 from the lens, and search for galaxy groups or clusters projected towards HE 0435−1223. We confirm that the lens is a member of a small group that includes at least 12 galaxies, and find 8 other group candidates near the line of sight of the lens. The flexion shift, namely the shift of lensed images produced by high order perturbation of the lens potential, is calculated for each galaxy/group and used to identify which objects produce the largest perturbation of the lens potential. This analysis demonstrates that i) at most three of the five brightest galaxies projected within 12 of the lens need to be explicitly used in the lens models, and ii) the groups can be treated in the lens model as an external tidal field (shear) contribution.

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“…The optical mass estimators we employ are mostly taken from the study of Pearson et al (2015), and we therefore reselect the member galaxies for each of our groups using the method employed by these authors. Galaxies are extracted from a cylindrical volume with a projected radius of 1 Mpc and a velocity depth ±3σ along the line of sight centred on the X-ray centroid where possible, where the velocity dispersion σ is derived using the gapper estimator of Beers, Flynn & Gebhardt (1990).…”

Section: Mass Estimation Qualitymentioning

confidence: 99%

“…observed group richness, (ii) luminosity (both extrapolated from the m r = 19.8 mag flux limit to a standard limiting absolute magnitude M r = −16.5 mag assuming a cluster luminosity function derived from the SDSS (Popesso et al 2005), (iii) galaxy, (iv) luminosity overdensity (from fits to an NFW radial density profile (Navarro et al 1996)), and (v) a dynamical mass estimator ∝σ 3α . These mass estimates, labelled M N , M L , M δ , M δ L and M σ , respectively, are based on mass-proxy relations that have been calibrated against M 500 from a sample of X-ray-selected groups, as described in Pearson et al (2015).…”

Section: Mass Estimation Qualitymentioning

confidence: 99%

Galaxy And Mass Assembly: search for a population of high-entropy galaxy groups

Pearson

Ponman

Norberg

et al. 2017

Monthly Notices of the Royal Astronomical Society

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On optical mass estimation methods for galaxy groups

Cited by 20 publications

References 68 publications

Galaxy cluster luminosities and colours, and their dependence on cluster mass and merger state

Galaxy cluster luminosities and colours, and their dependence on cluster mass and merger state

H0LiCOW – II. Spectroscopic survey and galaxy-group identification of the strong gravitational lens system HE 0435−1223

Galaxy And Mass Assembly: search for a population of high-entropy galaxy groups

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