The initial mass function of a massive relic galaxy

Martín-Navarro, I.; La Barbera, F.; Vazdekis, A.; Ferré-Mateu, A.; Trujillo, I.; Beasley, M. A.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 451, Issue 1, p.1081-1089

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7
2015
Number of authors
6
IAC number of authors
4
Citations
75
Refereed citations
73
Description
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 Re, the initial mass function (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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