NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-04-20 T17:54:32 PDT
Help | Comment | NED Home

For refcode 2010MNRAS.408..272S:
Retrieve 53 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by Royal Astronomical Society. 2010MNRAS.408..272S Early-type galaxies at large galactocentric radii - II. Metallicity gradients and the [Z/H]-mass, [{alpha}/Fe]-mass relations Spolaor, Max; Kobayashi, Chiaki; Forbes, Duncan A.; Couch, Warrick J.; Hau, George K. T. 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 x 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 initial mass function, energy feedback via active galactic nucleus and the effects due to merger-induced starbursts can also reproduce both our observed relationships. Key words: galaxies: abundances, galaxies: dwarf, galaxies: elliptical and lenticular, cD, galaxies: evolution, galaxies: formation, galaxies: stellar content
Retrieve 53 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home