Oral Presentation

Dynamical properties of massive quiescent galaxies at z~4

Author(s):

Presenter: Masayuki Tanaka (National Astronomical Obseravtory of Japan)

We present deep near-IR spectroscopic observations of massive quiescent galaxies at z~4 with Keck/MOSFIRE. It has been long known that the majority of stars in massive elliptical galaxies formed in an intense burst of star formation at high redshifts. However, the detailed physics of intense star formation followed by rapid quenching at high redshift is largely unknown. Recent observations have shown that a large fraction of massive galaxies even at z~2 are known to be quiescent, and the advent of sensitive near-IR spectrograph has made it possible to confirm such quiescent galaxies out to z~4. We have confirmed two quiescent galaxies at z~4 with MOSFIRE. Both of them are the highest redshift quiescent galaxies known to date. Interestingly, they are at different post-starburst phases; one has a stellar age of 0.1 Gyr, while the other is 0.5 Gyr. These galaxies grew massive in a short timescale and then experienced quenching as early as z=6. This deepens the question of massive galaxy formation with rapid quenching. We further discuss implications of our observations using the size-mass relation, stellar mass vs. dynamical mass relation, mass fundamental plane, etc.