2004ApJ...614..679L

Query : 2004ApJ...614..679L

2004ApJ...614..679L - Astrophys. J., 614, 679-691 (2004/October-3)

The color-magnitude effect in early-type cluster galaxies.

LOPEZ-CRUZ O., BARKHOUSE W.A. and YEE H.K.C.

Abstract (from CDS):

We present the analysis of the color-magnitude relation (CMR) for a sample of 57 X-ray-detected Abell clusters within the redshift interval 0.02≤z≤0.18. We use the B-R versus R color-magnitude plane to establish that the CMR is present in all our low-redshift clusters and can be parameterized by a single straight line. We find that the CMRs for this large cluster sample of different richness and cluster types are consistent with having universal properties. The k-corrected colors of the individual CMRs in the sample at a fixed absolute magnitude have a small intrinsic dispersion of ∼0.05 mag. The slope of the CMR is consistent with being the same for all clusters, with the variations entirely accountable by filter band shifting effects. We determine the mean of the dispersion of the 57 CMRs to be 0.074 mag, with a small rms scatter of 0.026 mag. However, a modest amount of the dispersion arises from photometric measurement errors and possible background cluster superpositions, and the derived mean dispersion is an upper limit. Models that explain the CMR in terms of metallicity and passive evolution can naturally reproduce the observed behavior of the CMR in this paper. The observed properties of the CMR are consistent with models in which the last episode of strong star formation in cluster early-type galaxies occurred significantly more than ∼3 Gyr ago and the core set of early-type galaxies in clusters were formed more than 7 Gyr ago. The universality of the CMR provides us with an important tool for cluster detection and redshift estimation. A very accurate photometric cluster redshift estimator can be devised based on the apparent color shift of the CMR due to redshift. This calibrator has the additional advantage of being very efficient since only two bands are needed. An empirically calibrated redshift estimator based on the B-R color of the CMR for clusters with z<0.20 produces an accuracy of Δz∼0.010. Background clusters, typically at z∼0.25 and previously unknown, are found in this survey in the color-magnitude diagrams as secondary CMRs to the red of the target cluster CMRs. We also find clear cases of apparent X-ray substructure that are due to these cluster superpositions. This suggests that X-ray observations of clusters are also subject to a significant amount of projection contaminations.

Abstract Copyright: ∼

Journal keyword(s): Galaxies: Clusters: General - Galaxies: Elliptical and Lenticular, cD - Galaxies: Photometry - Galaxy: Formation

Simbad objects: 58

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Number of rows : 58
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 ACO 21 ClG 00 20 38.75 +28 41 40.5           ~ 122 0
2 ACO 85 ClG 00 41 36.21 -09 19 30.4           ~ 974 0
3 ACO 84 ClG 00 41 36.85 +21 24 25.7           ~ 64 0
4 ACO 98 ClG 00 46 29.2 +20 28 06           ~ 150 0
5 ACO 154 ClG 01 10 58.1 +17 39 56           ~ 140 1
6 ACO 168 ClG 01 15 07.58 +00 19 10.8           ~ 379 2
7 ACO 260 ClG 01 50 46.811 +33 04 22.17           ~ 67 0
8 ACO 399 ClG 02 57 56.4 +13 00 59           ~ 420 0
9 ACO 401 ClG 02 58 50.3 +13 34 07           ~ 592 0
10 ACO 407 ClG 03 01 43.7 +35 49 48           ~ 113 0
11 ACO 415 ClG 03 06 47 -12 02.5           ~ 63 0
12 ACO 496 ClG 04 33 40.8 -13 14 34           ~ 728 2
13 ACO 514 ClG 04 48 18 -20 28.7           ~ 149 0
14 ACO 634 ClG 08 14 33 +58 02.9           ~ 99 0
15 ACO 629 ClG 08 15 00 +66 25.9           ~ 38 0
16 ACO 646 ClG 08 22 10.0 +47 05 58           ~ 102 1
17 ACO 671 ClG 08 28 48.68 +30 27 07.0           ~ 168 0
18 ACO 665 ClG 08 30 45.2 +65 52 55           ~ 457 0
19 ACO 690 ClG 08 39 14.34 +28 48 47.0           ~ 81 0
20 ACO 779 ClG 09 20 02.70 +33 45 29.7           ~ 261 0
21 ACO 957 ClG 10 14 02.35 -00 53 30.0           ~ 225 2
22 ACO 999 ClG 10 23 22.1 +12 51 48           ~ 91 1
23 ACO 1142 ClG 11 00 56.74 +10 30 15.2           ~ 157 1
24 ACO 1213 ClG 11 16 26.98 +29 16 23.9           ~ 155 0
25 ACO 1291 ClG 11 32 11.20 +56 01 31.3           ~ 135 0
26 ACO 1413 ClG 11 55 12.87 +23 23 46.9           ~ 456 0
27 NAME Virgo Cluster ClG 12 30 47.8 +12 23 07           ~ 7107 0
28 ACO 1569 ClG 12 36 19.49 +16 32 46.8           ~ 83 0
29 ACO 1650 ClG 12 58 42.0 -01 45 45           ~ 325 0
30 ACO 1656 ClG 12 59 44.40 +27 54 44.9           ~ 5141 2
31 ACO 1775 ClG 13 41 50.60 +26 21 10.6           ~ 324 0
32 ACO 1795 ClG 13 48 47.4 +26 34 55           ~ 1330 0
33 ACO 1913 ClG 14 26 43.42 +16 40 26.1           ~ 100 1
34 ACO 1983 ClG 14 52 59.33 +16 46 11.0           ~ 249 1
35 ACO 2022 ClG 15 04 18.34 +28 30 25.5           ~ 95 0
36 ACO 2029 ClG 15 10 54.2 +05 44 23           ~ 1020 0
37 ACO 2152 ClG 16 05 22.4 +16 26 55           ~ 165 0
38 ACO 2247 ClG 16 47 22 +81 34.0           ~ 59 0
39 ACO 2244 ClG 17 02 40.33 +34 02 58.7           ~ 301 0
40 ACO 2256 ClG 17 03 37.5 +78 37 23           ~ 928 1
41 ACO 2255 ClG 17 12 56.0 +64 04 06           ~ 605 0
42 ACO 2271 ClG 17 17 17.5 +78 01 00           ~ 70 0
43 ACO 2328 ClG 20 48 09.8 -17 50 14           ~ 78 0
44 ACO 2356 ClG 21 35 45.13 +00 11 21.1           ~ 46 0
45 ACO 2384 ClG 21 52 20.9 -19 32 53           ~ 117 0
46 ACO 2399 ClG 21 57 19.01 -07 50 57.5           ~ 197 0
47 ACO 2410 ClG 22 02 15.8 -09 50 10           ~ 65 0
48 ACO 2415 ClG 22 05 25.0 -05 35 23           ~ 124 1
49 ACO 2420 ClG 22 10 22.5 -12 11 13           ~ 126 0
50 ACO 2440 ClG 22 23 52.6 -01 35 47           ~ 137 1
51 ACO 2554 ClG 23 12 18.7 -21 30 54           ~ 100 1
52 ACO 2556 ClG 23 13 03.3 -21 37 40           ~ 83 0
53 ACO 2593 ClG 23 24 27.15 +14 33 40.2           ~ 231 0
54 ACO 2597 ClG 23 25 19.70 -12 07 27.7           ~ 572 0
55 ACO 2626 ClG 23 36 31.0 +21 09 36           ~ 265 0
56 ACO 2634 ClG 23 38 18.4 +27 01 37           ~ 515 2
57 ACO 2657 ClG 23 44 51.0 +09 08 40           ~ 280 3
58 ACO 2670 ClG 23 54 10.51 -10 23 06.8           ~ 364 0

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