VELOCITY DISPERSIONS AND STELLAR POPULATIONS OF THE MOST COMPACT AND MASSIVE EARLY-TYPE GALAXIES AT REDSHIFT ∼1 (original) (raw)
2011, The Astrophysical Journal
We present Gran-Telescopio-Canarias/OSIRIS optical spectra of 4 of the most compact and massive early-type galaxies in the Groth Strip Survey at redshift z ∼ 1, with effective radii R e = 0.5 − 2.4 kpc and photometric stellar masses M ⋆ = 1.2 − 4 × 10 11 M ⊙ . We find these galaxies have velocity dispersions σ = 156 − 236 km s −1 . The spectra are well fitted by single stellar population models with approximately 1 Gyr of age and solar metallicity. We find that: i) the dynamical masses of these galaxies are systematically smaller by a factor of ∼6 than the published stellar masses using BRIJK photometry; ii) when estimating stellar masses as 0.7×M dyn , a combination of passive luminosity fading with mass/size growth due to minor mergers can plausibly evolve our objects to match the properties of the local population of early-type galaxies.
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