2010MNRAS.402..447R


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.09CEST11:10:22

2010MNRAS.402..447R - Mon. Not. R. Astron. Soc., 402, 447-460 (2010/February-2)

Exploring the star formation history of elliptical galaxies: beyond simple stellar populations with a new line strength estimator.

ROGERS B., FERRERAS I., PELETIER R. and SILK J.

Abstract (from CDS):

We study the stellar populations of a sample of 14 elliptical galaxies in the Virgo cluster. Using spectra with high signal-to-noise ratio (S/N ≳ 100Å–1) we propose an alternative approach to the standard side-band method to measure equivalent widths (EWs). Our boosted median continuum is shown to map the EWs more robustly than the side-band method, minimizing the effect from neighbouring absorption lines and reducing the uncertainty at a given S/N. Our newly defined line strengths are more successful at disentangling the age-metallicity degeneracy. We concentrate on Balmer lines (Hβ, Hγ, Hδ), the G band and the combination [MgFe] as the main age and metallicity indicators. We go beyond the standard comparison of the observations with simple stellar populations (SSPs) and consider four different models to describe the star formation histories, either with a continuous star formation rate or with a mixture of two different SSPs. These models improve the estimates of the more physically meaningful mass-weighted ages. Composite models are found to give more consistent fits among individual line strengths and agree with an independent estimate using the spectral energy distribution. A combination of age- and metallicity-sensitive spectral features allows us to constrain the average age and metallicity. For a Virgo sample of elliptical galaxies our age and metallicity estimates correlate well with stellar mass or velocity dispersion, with a significant threshold around 5x1010M above which galaxies are uniformly old and metal rich. This threshold is reminiscent of the one found by Kauffmann et al. in the general population of Sloan Digital Sky Survey galaxies at a stellar mass 3x1010M. In a more speculative way, our models suggest that it is formation epoch and not formation time-scale what drives the mass-age relationship of elliptical galaxies.

Abstract Copyright: © 2009 The Authors. Journal compilation © 2009 RAS

Journal keyword(s): galaxies: elliptical and lenticular, cD - galaxies: evolution - galaxies: formation - galaxies: stellar content

Simbad objects: 15

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Number of rows : 15

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NGC 4239 GiG 12 17 14.9407244878 +16 31 52.734917127   13.5       ~ 115 0
2 NGC 4339 GiP 12 23 34.9404906978 +06 04 54.466056554   13.1       ~ 225 0
3 NGC 4365 GiG 12 24 28.228 +07 19 03.07   11.5       ~ 806 0
4 NGC 4387 GiG 12 25 41.6768872639 +12 48 37.809497625 13.42 13.01 12.12   10.87 ~ 374 1
5 NAME Vir I ClG 12 26 32.1 +12 43 24   10.00 8.49     ~ 6028 0
6 NGC 4458 GiP 12 28 57.532 +13 14 30.90 13.27 12.93 12.07     ~ 392 2
7 NGC 4464 GiG 12 29 21.313 +08 09 23.63   13.5       ~ 219 0
8 NGC 4467 GiG 12 29 30.267 +07 59 34.62   15.2       ~ 163 0
9 M 49 Sy2 12 29 46.798 +08 00 01.48   13.21 12.17     ~ 1990 2
10 NGC 4473 GiG 12 29 48.878 +13 25 45.55 11.60 11.16 10.20     ~ 612 1
11 NGC 4478 GiP 12 30 17.439 +12 19 42.88 12.82 12.36 11.45   10.17 ~ 474 1
12 NGC 4489 GiG 12 30 52.240 +16 45 31.31   13.2       ~ 242 0
13 NGC 4551 GiP 12 35 37.980 +12 15 50.44 13.49 12.97 12.02     ~ 337 1
14 M 59 GiG 12 42 02.322 +11 38 48.95   11.0       ~ 667 0
15 NGC 4697 GiG 12 48 35.8992791099 -05 48 02.497675635   10.97   9.83   ~ 814 0

    Equat.    Gal    SGal    Ecl

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2021.05.09-11:10:22

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