Barbera, FL;
Vazdekis, A;
Ferreras, I;
Pasquali, A;
Prieto, CA;
Rock, B;
Aguado, DS;
(2017)
IMF and [Na/Fe] abundance ratios from optical and NIR Spectral Features in Early-type Galaxies.
Monthly Notices of the Royal Astronomical Society
, 464
(3)
pp. 3597-3626.
10.1093/mnras/stw2407.
Preview |
Text
Barbera_IMF_Na-Fe_abundance._VoR.pdf - Published Version Download (1MB) | Preview |
Abstract
We present a joint analysis of the four most prominent sodium-sensitive features (NaD, NaI8190, NaI1.14, and NaI2.21), in the optical and Near-Infrared spectral range, of two nearby, massive (sigma~300km/s), early-type galaxies (named XSG1 and XSG2). Our analysis relies on deep VLT/X-Shooter long-slit spectra, along with newly developed stellar population models, allowing for [Na/Fe] variations, up to 1.2dex, over a wide range of age, total metallicity, and IMF slope. The new models show that the response of the Na-dependent spectral indices to [Na/Fe] is stronger when the IMF is bottom heavier. For the first time, we are able to match all four Na features in the central regions of massive early-type galaxies, finding an overabundance of [Na/Fe], in the range 0.5-0.7dex, and a bottom-heavy IMF. Therefore, individual abundance variations cannot be fully responsible for the trends of gravity-sensitive indices, strengthening the case towards a non-universal IMF. Given current limitations of theoretical atmosphere models, our [Na/Fe] estimates should be taken as upper limits. For XSG1, where line strengths are measured out to 0.8Re, the radial trend of [Na/Fe] is similar to [Mg/Fe] and [C/Fe], being constant out to 0.5Re, and decreasing by 0.2-0.3dex at 0.8Re, without any clear correlation with local metallicity. Such a result seems to be in contrast with the predicted increase of Na nucleosynthetic yields from AGB stars and TypeII SNe. For XSG1, the Na-inferred IMF radial profile is consistent, within the errors, with that derived from TiO features and the Wing-Ford band, presented in a recent paper.
| Type: | Article |
|---|---|
| Title: | IMF and [Na/Fe] abundance ratios from optical and NIR Spectral Features in Early-type Galaxies |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stw2407 |
| Publisher version: | http://dx.doi.org/10.1093/mnras/stw2407 |
| Language: | English |
| Additional information: | This is the published version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | galaxies: elliptical and lenticular, cD; galaxies: formation; galaxies: fundamental parameters; galaxies: stellar content |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/1522630 |
Archive Staff Only
 |
View Item |
