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arXiv · 1310.6367

NGC1277: a massive compact relic galaxy in the nearby Universe

Ignacio Trujillo·Anna Ferre-Mateu·Marc Balcells·Alexandre Vazdekis·Patricia Sanchez-Blazquez
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Abstract

As early as 10 Gyr ago, galaxies with more than 10^11 Msun in stars already existed. While most of these massive galaxies must have subsequently transformed through on-going star formation and mergers with other galaxies, a small fraction (<0.1%) may have survived untouched till today. Searches for such relic galaxies, useful windows to explore the early Universe, have been inconclusive to date: galaxies with masses and sizes like those observed at high redshift (M*>10^11 Msun; Re<1.5 kpc) have been found in the local Universe, but their stars are far too young for the galaxy to be a relic galaxy. This paper explores the first case of a nearby galaxy, NGC1277 (in the Perseus cluster at a distance of 73 Mpc), which fulfills all the criteria to be considered a relic galaxy. Using deep optical spectroscopy, we derive the star formation history along the structure of the galaxy: the stellar populations are uniformly old (>10 Gyr) with no evidence for more recent star formation episodes. The metallicity of their stars is super-solar ([Fe/H]=0.20+-0.04) and alpha enriched ([alpha/Fe]=0.4+-0.1). This suggests a very short formation time scale for the bulk of stars of this galaxy. This object also rotates very fast (Vrot~300 km/s) and has a large velocity dispersion (sigma>300 km/s). NGC1277 will allow future explorations in full detail of properties such as the structure, internal dynamics, metallicity, dust content and initial mass function at around 10-12 Gyr back in time when the first massive galaxies were built.

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Ignacio Trujillo, Anna Ferre-Mateu, Marc Balcells, Alexandre Vazdekis, Patricia Sanchez-Blazquez. 2013-10-23. NGC1277: a massive compact relic galaxy in the nearby Universe. https://doi.org/10.1088/2041-8205/780/2/l20

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