2016A&A...595A.111C -
Astronomy and Astrophysics, volume 595A, 111-111 (2016/11-1)
A new method to assign galaxy cluster membership using photometric redshifts.
CASTIGNANI G. and BENOIST C.
Abstract (from CDS):
We introduce a new effective strategy to assign group and cluster membership probabilities P_{mem} to galaxies using photometric redshift information. Large dynamical ranges both in halo mass and cosmic time are considered. The method takes into account the magnitude distribution of both cluster and field galaxies as well as the radial distribution of galaxies in clusters using a non-parametric formalism, and relies on Bayesian inference to take photometric redshift uncertainties into account. We successfully test the method against 1208 galaxy clusters within redshifts z=0.05-2.58 and masses 10^{13.29–14.80}M_{☉} drawn from wide field simulated galaxy mock catalogs mainly developed for the forthcoming Euclid mission. Median purity and completeness values of (55^{+17}_{–15})% and (95^{+5}_{–10})% are reached for galaxies brighter than 0.25L_{*} within r_{200} of each simulated halo and for a statistical photometric redshift accuracy σ((z_{s}-z_{p})/(1+z_{s}))=0.03. The mean values p=56% and c=93% are consistent with the median and have negligible sub-percent uncertainties. Accurate photometric redshifts (σ((z_{s}-z_{p})/(1+z_{s}))≤0.05) and robust estimates for the cluster redshift and cluster center coordinates are required. The dependence of the assignments on photometric redshift accuracy, galaxy magnitude and distance from the halo center, and halo properties such as mass, richness, and redshift are investigated. Variations in the mean values of both purity and completeness are globally limited to a few percent. The largest departures from the mean values are found for galaxies associated with distant z≥1.5 halos, faint (∼0.25L_{*}) galaxies, and those at the outskirts of the halo (at cluster-centric projected distances ∼r_{200}) for which the purity is decreased, Δp~=20% at most, with respect to the mean value. The proposed method is applied to derive accurate richness estimates. A statistical comparison between the true (N_{true}) vs. estimated richness (λ=∑P_{mem}) yields on average to unbiased results, Log(λ/N_{true})=-0.0051±0.15. The scatter around the mean of the logarithmic difference between λ and the halo mass is 0.10dex for massive halos ≥10^{14.5}M_{☉}. Our estimates could therefore be useful to constrain the cluster mass function and to calibrate independent cluster mass estimates such as those obtained from weak lensing, Sunyaev-Zel'dovich, and X-ray studies. Our method can be applied to any list of galaxy clusters or groups in both present and forthcoming surveys such as SDSS, CFHTLS, Pan-STARRS, DES, LSST, and Euclid.
(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases
Other object types:
X
(2A,3A,...),
ClG
(Ref,ACO,...),
gam
(IGR,INTREF),
GrG
(RASSCALS,[N93]),
gLe
(Ref),
C?G
(Ref),
Rad
(DB)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
quality : flag of quality
E ≥ 10"
D : 1-10" (and some old data)
C : 0.1-1"
B : 0.01-0.1" + 2MASS, Tyc
A : VLBI, Hipparcos
bibcode : bibcode of the coordinates reference
FK4
coord.
(ep=B1950 eq=1950) :
12 57 24.0 +28 14 59
[
]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
quality : flag of quality
E ≥ 10"
D : 1-10" (and some old data)
C : 0.1-1"
B : 0.01-0.1" + 2MASS, Tyc
A : VLBI, Hipparcos
bibcode : bibcode of the coordinates reference
Gal
coord.
(ep=J2000) :
058.0791 +87.9577
[
]
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
(redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
[error] : error of the corresponding value displayed before
(wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or '∼'(unknown)
quality : flag of quality ( A=best quality -> E=worst quality, {� } =unknown quality)
References (4132 between 1850 and 2020) (Total 4132)
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