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http://hdl.handle.net/20.500.12386/30846
Titolo: | Radial variations in the stellar initial mass function of early-type galaxies | Autori: | Ignacio Martín-Navarro LA BARBERA, Francesco Alexandre Vazdekis Jesús Falcón-Barroso Ignacio Ferreras |
Data pubblicazione: | 2015 | Rivista: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Numero: | 447 | Fascicolo: | 2 | Da pagina:: | 1033 | Abstract: | The hypothesis of a universal initial mass function (IMF) -- motivated by observations in nearby stellar systems -- has been recently challenged by the discovery of a systematic variation of the IMF with the central velocity dispersion, {\sigma}, of early-type galaxies (ETGs), towards an excess of low-mass stars in high-{\sigma} galaxies. This trend has been derived so far from integrated spectra, and remains unexplained at present. To test whether such trend depends on the local properties within a galaxy, we have obtained new, extremely deep, spectroscopic data, for three nearby ETGs, two galaxies with high {\sigma} (~300 km/s), and one lower mass system, with {\sigma} ~ 100 km/s. From the analysis of IMF-sensitive spectral features, we find that the IMF depends significantly on galactocentric distance in the massive ETGs, with the enhanced fraction of low-mass stars f mostly confined to their central regions. In contrast, the low-{\sigma} galaxy does not show any significant radial gradient in the IMF, well described by a shallower distribution, relative to the innermost regions of massive galaxies, at all radii. Such a result indicates that the IMF should be regarded as a local (rather than global) property, and suggests a significant difference between the formation process of the core and the outer regions of massive ETGs. | URI: | http://hdl.handle.net/20.500.12386/30846 | URL: | http://arxiv.org/abs/1404.6533v2 https://academic.oup.com/mnras/article/447/2/1033/2593650 |
ISSN: | 0035-8711 | DOI: | 10.1093/mnras/stu2480 | Bibcode ADS: | 2015MNRAS.447.1033M | Fulltext: | open |
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