| | |
| | |
Stat |
Members: 3645 Articles: 2'504'928 Articles rated: 2609
26 April 2024 |
|
| | | |
|
Article overview
| |
|
Early-type galaxies at large galactocentric radii - II. Metallicity gradients, and the [Z/H]--mass, [alpha/Fe]--mass relations | Max Spolaor
; Chiaki Kobayashi
; Duncan A. Forbes
; Warrick J. Couch
; George K. T. Hau
; | Date: |
9 Jun 2010 | Abstract: | We present the results of a study of stellar population properties at large
galactocentric radii of 14 low-mass early-type galaxies in the Fornax and Virgo
clusters. We derive radial profiles of Age, total metallicity [Z/H], and
[alpha/Fe] abundance ratios out to 1 - 3 effective radii by using nearly all of
the Lick/IDS absorption-line indices in comparison to recent single stellar
population models. We extend our study to higher galaxy mass via a novel
literature compilation of 37 early-type galaxies, which provides stellar
population properties out to one effective radius. We find that metallicity
gradients correlate with galactic mass, and the relationship shows a sharp
change in slope at a dynamical mass of 3.5 10^10 M_{sun}. The central and mean
values of the stellar population parameters (measured in r < r_e/8, and at r =
r_e, respectively) define positive mass trends. We suggest that the low
metallicities, almost solar [alpha/Fe] ratios and the tight mass-metallicity
gradient relation displayed by the low-mass galaxies are indicative of an early
star-forming collapse with extended (i.e., > 1 Gyr), low efficiency star
formation, and mass-dependent galactic outflows of metal-enriched gas. The
flattening of metallicity gradients in high-mass galaxies, and the broad
scatter of the relationship are attributed to merger events. The high
metallicities and supersolar abundances shown by these galaxies imply a rapid,
high efficiency star formation. The observed [Z/H]--mass and [alpha/Fe]--mass
relationships can be interpreted as a natural outcome of an early star-forming
collapse. However, we find that hierarchical galaxy formation models
implementing mass-dependent star formation efficiency, varying IMF, energy
feedback via AGN, and the effects due to merger-induced starbursts can also
reproduce both our observed relationships. | Source: | arXiv, 1006.1698 | Services: | Forum | Review | PDF | Favorites |
|
|
No review found.
Did you like this article?
Note: answers to reviews or questions about the article must be posted in the forum section.
Authors are not allowed to review their own article. They can use the forum section.
browser Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)
|
| |
|
|
|
| News, job offers and information for researchers and scientists:
| |