Fernando Buitrago, Christopher J. Conselice, Benoit Epinat, Alejandro G. Bedregal, Ruth Grutzbauch
There is cumulative evidence showing that, for the most massive galaxies, the fraction of disk-like objects compared to those with spheroidal properties increases with redshift. However, this evidence is thus far based on detailed morphological analyses of these objects which ultimately rests on the shape of their surface brightness profiles. To explore the consistency of this scenario, it is necessary to measure the dynamical status of these galaxies. With this aim we have obtained near-infrared integral field spectra in the H-band for 10 massive galaxies (M_{stellar} >10^{11} h_{70}^-2 M_{Sun}) at z~1.4 with SINFONI at the VLT. Our sample is selected by their stellar mass and EW[OII] > 15\AA, to secure their kinematic measurements, but without accounting for any morphological or flux criteria a priori. Through this 3D kinematic spectroscopy analysis we find that half (i.e. 50+/-7%) of our galaxies are compatible with being rotationally supported disks, in agreement with previous morphological expectations. This is a factor of approximately two higher than what is observed in the present Universe for objects of the same stellar mass. Strikingly, the majority of our sample of massive galaxies show clear and fairly large rotational velocity maps, implying that massive galaxies acquire rapidly rotational support and hence gravitational equilibrium. Our sample also show evidence for ongoing interactions and mergers. This demonstrates that massive galaxies at this epoch are not a homogenous sample, but show significant diversity and must have continued evolution beyond the fading of stellar populations, to become the massive galaxies we find in today's Universe.
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http://arxiv.org/abs/1305.0268
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