2003A&A...407..423M


Query : 2003A&A...407..423M

2003A&A...407..423M - Astronomy and Astrophysics, volume 407, 423-435 (2003/8-4)

Spatially resolved spectroscopy of Coma cluster early-type galaxies. III. The stellar population gradients.

MEHLERT D., THOMAS D., SAGLIA R.P., BENDER R. and WEGNER G.

Abstract (from CDS):

Based on Paper I of this series (Mehlert et al., 2000A&AS..141..449M), we derive central values and logarithmic gradients for the Hβ, Mg and Fe indices of 35 early-type galaxies in the Coma cluster. We find that pure elliptical galaxies have on average slightly higher velocity dispersions, lower Hβ, and higher metallic line-strengths than galaxies with disks (S0). The latter form two families, one comparable to the ellipticals and a second one with significantly higher Hβ, and weaker metallic lines. Our measured logarithmic gradients within the effective radius are <ΔMg b≥~-0.037, <Δ <Fe≫≃-0.029, <ΔHβ≥~+0.017 and <Δσ≥~-0.063. The gradients strongly correlate with the gradients of σ, but only weakly with the central index values and galaxy velocity dispersion. Using stellar population models with variable element abundance ratios from Thomas et al. (2003MNRAS.339..897T) we derive average ages, metallicities and [α/Fe] ratios in the center and at the effective radius. We find that the α/Fe ratio correlates with velocity dispersion and drives 30% of the Mg-σ relation, the remaining 70% being caused by metallicity variations. We confirm previous findings that part of the lenticular galaxies in the Coma cluster host very young (∼2Gyr) stellar populations, hence must have experienced relatively recent star formation episodes. Again in accordance with previous work we derive negative metallicity gradients (~-0.16dex per decade) that are significantly flatter than what is expected from gaseous monolithic collapse models, pointing to the importance of mergers in the galaxy formation history. Moreover, the metallicity gradients correlate with the velocity dispersion gradients, confirming empirically earlier suggestions that the metallicity gradient in ellipticals is produced by the local potential well. The gradients in age are negligible, implying that no significant residual star formation has occurred either in the center or in the outer parts of the galaxies, and that the stellar populations at different radii must have formed at a common epoch. For the first time we derive the gradients of the α/Fe ratio and find them very small on average. Hence, α/Fe enhancement is not restricted to galaxy centers but it is a global phenomenon. Our results imply that the Mg-σ local relation inside a galaxy, unlike the global Mg-σ relation, must be primarily driven by metallicity variations alone. Finally we note that none of the stellar population parameters or their gradients depend on the density profile of the Coma cluster, even though it spans 3dex in density.

Abstract Copyright:

Journal keyword(s): galaxies: clusters: individual: Coma - galaxies: elliptical and lenticular, cD - galaxies: stellar content

VizieR on-line data: <Available at CDS (J/A+A/407/423): position.dat tablea1.dat tablea2.dat tablea3.dat>

Simbad objects: 36

goto Full paper

goto View the references in ADS

Number of rows : 36
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 NGC 4807 GiP 12 55 29.1008459472 +27 31 17.156306460   14.50 13.50     ~ 103 1
2 NGC 4816 GiG 12 56 12.1508733240 +27 44 43.773192276 14.25 13.80 12.84     ~ 137 1
3 NGC 4827 LIN 12 56 43.5187101000 +27 10 43.654438128   13.90 12.91     ~ 122 1
4 NGC 4839 rG 12 57 24.3563164776 +27 29 52.203087132 13.56 13.02 12.06     ~ 465 3
5 NGC 4841 LIN 12 57 31.978 +28 28 36.86   13.5       ~ 147 0
6 NGC 4840 LIN 12 57 32.8380921120 +27 36 37.243946592   14.8       ~ 110 0
7 LEDA 83695 GiC 12 57 46.1623966512 +27 45 25.345511748   15       ~ 45 0
8 NGC 4850 AGN 12 58 21.8338490568 +27 58 04.024808724 15.43 15.3 14.03     ~ 98 0
9 IC 3947 AG? 12 58 52.1045260536 +27 47 06.266103540 16.00 15.866 14.61 14.341 13.633 ~ 91 0
10 NGC 4860 GiG 12 59 03.9057463440 +28 07 25.326557148 14.84 14.7 13.24     ~ 154 0
11 3XMM J125913.6+272409 LIN 12 59 13.7080797336 +27 24 09.261692784   15.4       ~ 66 0
12 NGC 4865 EmG 12 59 19.8737739096 +28 05 03.488821044 15.06 14.6 13.692 13.131 12.443 ~ 112 0
13 NGC 4869 rG 12 59 23.3588349024 +27 54 41.731884360 15.03 14.9 13.52 13.292 12.536 ~ 278 0
14 NGC 4871 AGN 12 59 29.9631023208 +27 57 23.169658968 15.59 15.1 14.07 13.801 13.113 ~ 116 0
15 NGC 4872 AGN 12 59 34.1212116072 +27 56 48.678716616 15.58 14.7 14.10 14.092 13.423 ~ 139 0
16 NGC 4874 LIN 12 59 35.7093764280 +27 57 33.293892204 13.01 13.7 11.40 12.122 11.386 ~ 779 3
17 NGC 4876 LIN 12 59 44.4043327032 +27 54 44.883805032 15.61 15.1 14.18 13.992 13.333 ~ 149 0
18 ACO 1656 ClG 12 59 44.40 +27 54 44.9           ~ 4763 2
19 NGC 4883 GiG 12 59 56.0172515304 +28 02 04.976091780 15.76 15.2 14.27 13.872 13.165 ~ 106 0
20 NGC 4889 EmG 13 00 08.097 +27 58 37.29 12.93 13.0 11.30 11.652 10.906 ~ 703 1
21 NGC 4895 LIN 13 00 17.9283615768 +28 12 08.593323732 14.57 14.3 13.09     ~ 108 0
22 LEDA 83746 GiC 13 00 19.1059455024 +27 33 13.409044308   14       ~ 41 0
23 NGC 4896 LIN 13 00 30.7683020616 +28 20 46.935237984   15.1       ~ 84 0
24 IC 4041 EmG 13 00 40.8541511496 +27 59 47.807863512 16.19 15.88 14.77 14.343 13.733 ~ 105 0
25 IC 4045 AGN 13 00 48.6521997192 +28 05 26.675160468 15.25 15.1 13.77 13.573 12.895 ~ 148 0
26 NGC 4908 LIN 13 00 51.5428778808 +28 02 34.346182596 15.05 14.9 13.58 13.273 12.566 ~ 121 0
27 MCG+05-31-095 LIN 13 00 52.0847397072 +28 21 58.080590892 14.99 14.9 13.56     ~ 75 0
28 IC 4051 EmG 13 00 54.4630403184 +28 00 27.502143300 15.04 14.8 13.50 13.003 12.305 ~ 213 0
29 NGC 4923 EmG 13 01 31.7992415376 +27 50 51.100173564   14.7       ~ 111 0
30 IC 843 LIN 13 01 33.5886614256 +29 07 49.984080384   14.62 13.84 15.24   ~ 84 1
31 2MFGC 10339 LIN 13 01 47.0185231920 +28 05 41.988686424   15.2       ~ 63 0
32 NGC 4926 LIN 13 01 53.7302453520 +27 37 28.027389360   14.1       ~ 157 0
33 NGC 4931 GiG 13 03 00.8766606384 +28 01 56.920384380   14.4       ~ 87 0
34 NGC 4944 GiG 13 03 49.9449729120 +28 11 08.552500332   13.3   12.69   ~ 100 0
35 NGC 4952 LIN 13 04 58.3849361808 +29 07 20.011981188   13.39 13.01     ~ 94 1
36 NGC 4957 GiG 13 05 12.3897926664 +27 34 11.130658716   14.2   14.62   ~ 90 0

To bookmark this query, right click on this link: simbad:objects in 2003A&A...407..423M and select 'bookmark this link' or equivalent in the popup menu