J/MNRAS/478/5473 X-ray-selected galaxy clusters BCG offsets (Lopes+, 2018)
Optical substructure and BCG offsets of Sunyaev-Zel'dovich and
X-ray-selected galaxy clusters.
Lopes P.A.A., Trevisan M., Lagana T.F., Durret F., Ribeiro A.L.B.,
Rembold S.B.
<Mon. Not. R. Astron. Soc., 478, 5473-5490 (2018)>
=2018MNRAS.478.5473L 2018MNRAS.478.5473L (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; X-ray sources
Keywords: galaxies: clusters: general -
galaxies: clusters: intracluster medium - X-rays: galaxies: clusters
Abstract:
We used optical imaging and spectroscopic data to derive substructure
estimates for local Universe (z<0.11) galaxy clusters from two
different samples. The first was selected through the
Sunyaev-Zel'dovich (SZ) effect by the Planck satellite, and the second
is an X-ray-selected sample. In agreement to X-ray substructure
estimates, we found that the SZ systems have a larger fraction of
substructure than the X-ray clusters. We have also found evidence that
the higher mass regime of the SZ clusters, compared to the X-ray
sample, explains the larger fraction of disturbed objects in the
Planck data. Although we detect a redshift evolution in the
substructure fraction, it is not sufficient to explain the different
results between the higher-z SZ sample and the X-ray one. We have also
verified a good agreement (∼60 per cent) between the optical
and X-ray substructure estimates. However, the best level of agreement
is given by the substructure classification given by measures based on
the brightest cluster galaxy (BCG), either the BCG-X-ray centroid
offset, or the magnitude gap between the first and second BCGs. We
advocate the use of those two parameters as the most reliable and
cheap way to assess cluster dynamical state. We recommend an offset
cut-off ∼0.01xR500 to separate relaxed and disturbed
clusters. Regarding the magnitude gap, the separation can be done at
Δm12=1.0. The central galaxy paradigm (CGP) may not be valid
for ∼20 per cent of relaxed massive clusters. This fraction
increases to ∼60 per cent for disturbed systems.
Description:
This work is based on the two samples presented by Andrade-Santos et
al. (2017ApJ...843...76A 2017ApJ...843...76A, Cat. J/ApJ/843/76). The first is based on
the Planck Early Sunyaev-Zel'dovich (ESZ) sample of 189 SZ
clusters, containing 164 clusters at z<0.35. These clusters have
been followed up in X-rays by the Chandra-Planck Legacy Program for
Massive Clusters of Galaxies
(hea-www.cfa.harvard.edu/CHANDRAPLANCKCLUSTERS). The second data set
is composed of 100 clusters from a flux-limited X-ray sample for which
Chandra data are also available. Most (∼90 per cent) of the
clusters in this data set are located below z=0.1, with the
remaining objects spread up to z∼0.2. The Planck ESZ and X-ray
samples have 49 clusters in common.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 125 72 Main properties of the 72 clusters
tablea2.dat 113 72 Substructure measures, BCG coordinates, offsets
and magnitude gaps for the 72 clusters
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- Name Name
17- 25 F9.5 deg RAdeg Right ascension (J2000)
27- 35 F9.5 deg DEdeg Declination (J2000)
37- 42 F6.4 --- z Heliocentric redshift
44- 49 F6.1 km/s sigmaP Velocity dispersion
51- 55 F5.1 km/s E_sigmaP Error on sigmaP, upper value
57- 61 F5.1 km/s e_sigmaP Error on sigmaP, lower value
63- 66 F4.2 Mpc R500 Radius within which the matter density is
500 times the critical density for the
total and dark matter profiles
68- 71 F4.2 Mpc E_R500 Error on R500, upper value
73- 76 F4.2 Mpc e_R500 Error on R500, lower value
78- 82 F5.2 10+14Msun M500 Mass of the cluster within R200
84- 87 F4.2 10+14Msun E_M500 Error on M500, upper value
89- 92 F4.2 10+14Msun e_M500 Error on M500, lower value
94- 97 F4.2 Mpc R200 Radius within which the matter density is
200 times the critical density for the
total and dark matter profiles
99-103 F5.2 Mpc E_R200 Error on R200, upper value
105-108 F4.2 Mpc e_R200 Error on R200, lower value
110-114 F5.2 10+14Msun M200 Mass of the cluster within R500
116-120 F5.2 10+14Msun E_M200 Error on M200, upper value
122-125 F4.2 10+14Msun e_M200 Error on M200, lower value
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name Name
16- 20 F5.1 --- beta Symmetry (beta) test (1)
22- 26 F5.3 --- betas beta test significance (1)
28- 32 F5.1 --- DELTA Dressler & Shectman ({DELTA}) test (1)
34- 38 F5.3 --- DELTAs DELTA test significance (1)
40- 42 F3.1 --- L3D Dressler & Shectman (DS) and Lee 3D tests (1)
44- 48 F5.3 --- L3Ds DS and Lee 3D tests significance (1)
50- 52 F3.1 --- AD Anderson-Darling (AD) statistic
54- 60 E7.2 --- pAD p-value associated to AD statistic
62- 70 F9.5 deg RAdeg BCG right ascension (J2000)
72- 80 F9.5 deg DEdeg BCG declination (J2000)
82- 87 F6.2 --- rMAG BCG r absolute magnitude
89- 93 F5.2 --- Dm12 Luminosity gap, {DELTA}m12
95- 99 F5.1 kpc Offset Offset to the X-ray centre (in kpc)
101-105 F5.3 --- Offset2 Offset to the X-ray centre (in R500)
107-113 F7.1 --- DVBGC BCG velocity offset
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Note (1): Values of the three substructure tests from Pinkney et al.
(1996ApJS..104....1P 1996ApJS..104....1P).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 28-Oct-2021