From a search of a portion of the sky covered by the SDSS and UKIDSS databases , we have located 2 galaxies at z \sim 0.5 that have properties similar to those of the luminous passive compact galaxies found at z \sim 2.5 .
From Keck moderate-resolution spectroscopy and laser-guided adaptive-optics imaging of these galaxies , we can begin to put together a more detailed picture of what their high-redshift counterparts might be like .
Spectral-synthesis models that fit the u to K photometry also seem to give good fits to the spectral features .
From these models , we estimate masses in the range of 3– 4 \times 10 ^ { 11 } M _ { \odot } for both galaxies .
Under the assumption that these are spheroidal galaxies , our velocity dispersions give estimated masses about a factor of 3 smaller .
However , our high-resolution imaging data indicate that these galaxies are not normal spheroids , and the interpretation of the kinematic data depends critically on the actual morphologies and the nature of the stellar orbits .
While recent suggestions that the population of high-redshift compact galaxies is present locally as the inner regions of local massive elliptical galaxies are quite plausible , the peak mass surface densities of the two galaxies we discuss here appear to be up to a factor of 10 higher than those of the highest density local ellipticals , assuming that our photometric masses are roughly correct .
It thus seems possible that some dynamical “ puffing-up ” of the high-redshift galaxies might still be required in this scenario .