2006A&A...446...31T


Query : 2006A&A...446...31T

2006A&A...446...31T - Astronomy and Astrophysics, volume 446, 31-38 (2006/1-4)

The ESO nearby Abell cluster survey. IX. The morphology-radius and morphology-density relations in rich galaxy clusters.

THOMAS T. and KATGERT P.

Abstract (from CDS):

We study the morphology-radius and morphology-density relations for a sample of about 850 galaxies (with MR≤-19.5) in 23 clusters from the ENACS (ESO Nearby Abell Cluster Survey). On the basis of their radial distributions we must distinguish: (i) the brightest ellipticals (with MR←22); (ii) the late spirals, and (iii) the ensemble of the less bright ellipticals, the S0 galaxies and the early spirals, which have indistinguishable distributions of projected radial distance R. The brightest ellipticals are most centrally concentrated, while the late spirals are almost absent from the central regions; the radial distribution of the other galaxy classes is intermediate. The previously found radial segregation of the ellipticals thus appears to be due to the brightest ellipticals only, while that of the spirals is due to the late spirals only. The morphology-density (MD-) relation was derived with two measures of projected density: one using the 10 nearest neighbours (Σ10) and another using only the nearest neighbour (Σ1). In the Σ10 MD-relation, only the classes of early- and late-type galaxies show a significant difference, but the different galaxy types within those classes are indistinguishable. However, this result is affected by significant cross-talk from the morphology-radius (or MR-) relation, as Σ10 is strongly correlated with R. Σ1 appears much less correlated with R and therefore the crosstalk from the MR-relation is much smaller. As a result, the normal ``ellipticals'' (with MR≥-22), the S0 galaxies and the early spirals do have different Σ1-distributions. On average, the ``normal'' ellipticals populate environments with higher projected density than do the S0 galaxies while the early spirals populate even less dense environments. We conclude that the segregation of the brightest ellipticals and the late spirals is driven primarily by global factors, while the segregation between ``normal'' ellipticals, S0 galaxies and early spirals is driven mostly by local factors. We discuss briefly the implications of these results in terms of scenarios for formation and transformation of galaxies in clusters.

Abstract Copyright:

Journal keyword(s): galaxies: clusters: general - galaxies: interactions - galaxies: evolution

Simbad objects: 21

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Number of rows : 21
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 ACO 2734 ClG 00 11 21.60 -28 51 16.6           ~ 137 0
2 ACO 2799 ClG 00 37 28.1 -39 08 59           ~ 40 0
3 ACO 87 ClG 00 43 01 -09 47.6           ~ 46 0
4 ACO 119 ClG 00 56 16.8 -01 15 00           ~ 543 2
5 ACO 151 ClG 01 08 52.3 -15 25 01           ~ 185 1
6 ACO 168 ClG 01 15 09.8 +00 14 51           ~ 350 2
7 ACO 3122 ClG 03 22 10.9 -41 20 15           ~ 57 0
8 ACO 3128 ClG 03 30 34.6 -52 33 12           ~ 173 3
9 ACO 3158 ClG 03 42 39.6 -53 37 50           ~ 290 0
10 ACO 3223 ClG 04 08 34.5 -30 49 08           ~ 52 2
11 ACO 3341 ClG 05 25 31.859 -31 35 56.05           ~ 51 0
12 ACO 548 ClG 05 47 01.7 -25 36 59           B8 200 2
13 ACO 754 ClG 09 08 50.1 -09 38 12           ~ 654 1
14 ACO 957 ClG 10 13 38.42 -00 55 32.6           ~ 202 2
15 ACO 978 ClG 10 20 26.66 -06 31 37.5           ~ 125 1
16 ACO 3528 ClG 12 54 18.2 -29 01 16           ~ 153 1
17 ACO 2040 ClG 15 12 45.2 +07 25 48           ~ 138 1
18 ACO 2052 ClG 15 16 45.5 +07 00 01           ~ 710 1
19 ACO 3651 ClG 19 52 10.9 -55 05 16           ~ 62 0
20 ACO 3667 ClG 20 12 33.68 -56 50 26.3           ~ 602 1
21 ACO 2401 ClG 21 58 52 -20 05.6           ~ 67 0

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2023.02.09-07:36:46

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