FORMING COMPACT MASSIVE GALAXIES

著者: Pieter G. van Dokkum, Erica June Nelson, Marijn Franx, Pascal Oesch, Ivelina Momcheva, Gabriel Brammer, Natascha M. Förster Schreiber, Rosalind E. Skelton, Katherine E. Whitaker, Arjen van der Wel, Rachel Bezanson, Mattia Fumagalli, Garth D. Illingworth, Mariska Kriek, Joel Leja, Stijn Wuyts - The Astrophysical Journal 2015 被引用: 301

In this paper we study a key phase in the formation of massive galaxies: the transition of star-forming galaxies into massive (M stars 10 11 M e ), compact (r e 1 kpc) quiescent galaxies, which takes place from z 3 to z 1.5. We use HST grism redshifts and extensive photometry in all five 3D-HST/CANDELS fields, more than doubling the area used previously for such studies, and combine these data with Keck MOSFIRE and NIRSPEC spectroscopy. We first confirm that a population of massive, compact, star-forming galaxies exists at z 2, using K-band spectroscopy of 25 of these objects at 2.0 < z < 2.5. They have a median [N II]/H ratio of 0.6, are highly obscured with SFR(tot)/SFR(H) 10, and have a large range of observed line widths. We infer from the kinematics and spatial distribution of H that the galaxies have rotating disks of ionized gas that are a factor of 2 more extended than the stellar distribution. By combining measurements of individual galaxies, we find that the kinematics are consistent with a nearly Keplerian fall-off from V rot 500 km s -1 at 1 kpc to V rot 250 km s -1 at 7 kpc, and that the total mass out to this radius is dominated by the dense stellar component. Next, we study the size and mass evolution of the progenitors of compact massive galaxies. Even though individual galaxies may have had complex histories with periods of compaction and mergers, we show that the population of progenitors likely followed a simple inside-out growth track in the size-mass plane of r M log 0.3 log . e s t a r s