Hostname: page-component-7479d7b7d-qs9v7 Total loading time: 0 Render date: 2024-07-12T23:24:02.160Z Has data issue: false hasContentIssue false

Ages and metallicities of early-type galaxies

Published online by Cambridge University Press:  13 April 2010

Ricardo Ogando
Affiliation:
Grupo de Pesquisas em Astronomia, Observatório Nacional, 20921-400, Rio de Janeiro, Brazil email: ogando@on.br, maia@on.br, pssp@on.br, ldacosta@on.br Instituto de Física, UFRJ, Box 68528, Rio de Janeiro, Brazil (former PhD student)
Marcio Maia
Affiliation:
Grupo de Pesquisas em Astronomia, Observatório Nacional, 20921-400, Rio de Janeiro, Brazil email: ogando@on.br, maia@on.br, pssp@on.br, ldacosta@on.br
Paulo Pellegrini
Affiliation:
Grupo de Pesquisas em Astronomia, Observatório Nacional, 20921-400, Rio de Janeiro, Brazil email: ogando@on.br, maia@on.br, pssp@on.br, ldacosta@on.br
Luiz da Costa
Affiliation:
Grupo de Pesquisas em Astronomia, Observatório Nacional, 20921-400, Rio de Janeiro, Brazil email: ogando@on.br, maia@on.br, pssp@on.br, ldacosta@on.br
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The study of stellar populations in early-type galaxies give us clues on how they form and evolve. We calculate age, [Z/H], and [α/Fe] ratio for 162 early-type galaxies using the SSP models from Thomas, Maraston, & Bender (2003) applied to Lick indices measurements, such as Hβ, Mgb, Fe5270 and Fe5335. Those were obtained from longslit spectra observed in the ESO 1.52m telescope as described in Ogando et al. (2008). We study the relations between the SSP parameters and velocity dispersion, as well as the influence of environment on these relations. We find that age, [Z/H], and [α/Fe] correlate well with velocity dispersion, so that more massive galaxies, have on average, higher metallicities, ages and abundance ratios than that of the low-mass ones. Galaxies in high density regions are older and more metal-rich than those in regions with low number of neighbors. These results are not consistent with standard predictions of hierarchical clustering. In the last decade, this “anti-hierarchical” behavior has also been generally tagged as downsizing and has challenged the current theoretical framework of galaxy formation, calling for new ways of star formation regulation in early-type galaxies.

Type
Poster Papers
Copyright
Copyright © International Astronomical Union 2010

References

Cimatti, A., Daddi, E., Renzini, A. et al. 2004, Nature, 430, 184CrossRefGoogle Scholar
Cowie, L. L., Songaila, A., Hu, E. M., & Cohen, J. G. 1996, AJ, 112, 839CrossRefGoogle Scholar
De Lucia, G., Springel, V., White, S. D. M. et al. 2006, MNRAS, 366, 499CrossRefGoogle Scholar
Kauffmann, G., White, S. D. M., & Guiderdoni, B. 1993, MNRAS, 264, 201CrossRefGoogle Scholar
Ogando, R. L. C., Maia, M. A. G., Pellegrini, P. S., & da Costa, L. N. 2008, AJ, 135, 2424CrossRefGoogle Scholar
Ogando, R. L. C., Maia, M. A. G., Pellegrini, P. S., & da Costa, L. N. 2010, in preparationGoogle Scholar
Thomas, D., Maraston, C., & Bender, R. 2003, MNRAS, 339, 897CrossRefGoogle Scholar
Trager, S. C., Faber, S. M., Worthey, G., & González, J. J. 2000a, AJ, 119, 1645CrossRefGoogle Scholar
Sánchez-Blázquez, P., Gorgas, J., Cardiel, N. et al. 2006b, A&A, 457, 809Google Scholar