%0 Generic %1 labarbera2016abundance %A La Barbera, F. %A Vazdekis, A. %A Ferreras, I. %A Pasquali, A. %A Prieto, C. Allende %A Rock, B. %A Aguado, D. S. %A Peletier, R. F. %D 2016 %K IMF abundance early galaxies ratio type %T IMF and Na/Fe abundance ratios from optical and NIR Spectral Features in Early-type Galaxies %U http://arxiv.org/abs/1610.03853 %X 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.

@misc{labarbera2016abundance, 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.}, added-at = {2016-10-14T09:23:58.000+0200}, author = {La Barbera, F. and Vazdekis, A. and Ferreras, I. and Pasquali, A. and Prieto, C. Allende and Rock, B. and Aguado, D. S. and Peletier, R. F.}, biburl = {https://www.bibsonomy.org/bibtex/22a3feb0ae443d116d0b600520695324b/miki}, description = {[1610.03853] IMF and [Na/Fe] abundance ratios from optical and NIR Spectral Features in Early-type Galaxies}, interhash = {1f8aaa65b2a2134dae6c700bd408194d}, intrahash = {2a3feb0ae443d116d0b600520695324b}, keywords = {IMF abundance early galaxies ratio type}, note = {cite arxiv:1610.03853Comment: 22 pages, 8 figure, accepted for publication in MNRAS. The new Na-enhanced models will be available soon at http://miles.iac.es/}, timestamp = {2016-10-14T09:23:58.000+0200}, title = {IMF and [Na/Fe] abundance ratios from optical and NIR Spectral Features in Early-type Galaxies}, url = {http://arxiv.org/abs/1610.03853}, year = 2016 }