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arXiv · 1505.01485

The initial mass function of a massive relic galaxy

Ignacio Martín-Navarro·Francesco La Barbera·Alexandre Vazdekis·Anna Ferré-Mateu·Ignacio Trujillo·Michael A. Beasley
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Abstract

Massive relic galaxies formed the bulk of their stellar component before z~2 and have remained unaltered since then. Therefore, they represent a unique opportunity to study in great detail the frozen stellar population properties of those galaxies that populated the primitive Universe. We have combined optical to near-infrared line-strength indices in order to infer, out to 1.5 Reff, the IMF of the nearby relic massive galaxy NGC 1277. The IMF of this galaxy is bottom-heavy at all radii, with the fraction of low-mass stars being at least a factor of two larger than that found in the Milky Way. The excess of low-mass stars is present throughout the galaxy, while the velocity dispersion profile shows a strong decrease with radius. This behaviour suggests that local velocity dispersion is not the only driver of the observed IMF variations seen among nearby early-type galaxies. In addition, the excess of low-mass stars shown in NGC 1277 could reflect the effect on the IMF of dramatically different and intense star formation processes at z~2, compared to the less extreme conditions observed in the local Universe.

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Ignacio Martín-Navarro, Francesco La Barbera, Alexandre Vazdekis, Anna Ferré-Mateu, Ignacio Trujillo, Michael A. Beasley. 2015-05-21. The initial mass function of a massive relic galaxy. https://doi.org/10.1093/mnras%2Fstv1022

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