Thursday, 15 April 2010
A z=1.82 Analog of Local Ultra-massive Elliptical Galaxies
This figure by Onodera et al. shows a velocity dispersion (red-filled circle) of a massive galaxy at z=1.82 in comparison to others (i.e. SDDS, Cappellari et al. 2009, van Dokkum et al. 2009). The velocity dispersion was measured from a 4.7 hours spectrum obtained with MOIRCS on Subaru. They find that their observations (morphology, size, and velocity dispersion) are fully consistent with those expected for passively evolving progenitors of today's giant ellipticals. I particularly like their conclusion: "It is clear that many more observations of similar galaxies are required to establish which kind of ETG is commonest at high redshift: either the compact/high-velocity dispersion objects like those found by van Dokkum et al. (2009), or the apparently normal, low- velocity dispersion objects presented in this paper."