Day 821

Thursday.

1501.04977
Quiescent compact galaxies at intermediate redshift in the COSMOS field II.  The fundamental plane of massive galaxies
Zahid, et al

~150 massive quiescent galaxies with an average sigma ~ 250 km/s and 0.2<z>0.8.  More than half of the galaxies in the sample are compact.  The COSMOS galaxies exhibit a tight relation (~0.1 dex scatter) between surface brightness, velocity dispersion and size.  At a fixed combination of velocity dispersion and size, the COSMOS galaxies are brighter than galaxies in the local universe.  The surface brightness offsets are correlated with the rest-frame g-z color and D_n4000 index; bluer galaxies and those with smaller D_n4000 indices have larger offsets.  Stellar population synthesis models indicate that the massive COSMOS galaxies are younger and therefore brighter than similarly massive quiescent galaxies in the local universe.  Passive evolution alone brings the massive compact quiescent COSMOS galaxies into the local fundamental plane at z=0.  Therefore, evolution in size or velocity dispersion for massive compact quiescent galaxies since z~1 is constrained by the small scatter observed in the fundamental plane.  Conclude that massive compact quiescent galaxies at z<~1 are not a special class of objects but rather the tail of the mass and size distribution of the normal quiescent galaxy population.