THE ASSEMBLY HISTORIES OF QUIESCENT GALAXIES SINCE z = 0.7 FROM ABSORPTION LINE SPECTROSCOPY

We present results from modeling the optical spectra of a large sample of quiescent galaxies between 0.1 1 indicate the inhomogeneous nature of the z ≲ 0.7 quiescent population. The data also permit the addition of newly quenched galaxies at masses below ∼10{sup 10.5} M {sub ☉} at z < 0.7. Additionally, we analyze very deep Keck DEIMOS spectra of the two brightest quiescent galaxies in a cluster at z = 0.83. There is tentative evidence that these galaxies are older than their counterparts in low-density environments. In the Appendix, we demonstrate that our full spectrum modeling technique allows for accurate and reliable modeling of galaxy spectra to low S/N (∼20 A{sup –1}) and/or low spectral resolution (R ∼ 500).« less