The initial mass function of a massive relic galaxy
  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.
