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MOSFIRE Spectroscopy of Quiescent Galaxies at 1.5 < z < 2.5. I. Evolution of Structural and Dynamical Properties

Belli, Sirio and Newman, Andrew B. and Ellis, Richard S. (2017) MOSFIRE Spectroscopy of Quiescent Galaxies at 1.5 < z < 2.5. I. Evolution of Structural and Dynamical Properties. Astrophysical Journal, 834 (1). Art. No. 18. ISSN 0004-637X.

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We present deep near-infrared spectra for a sample of 24 quiescent galaxies in the redshift range 1.5 < z < 2.5 obtained with the MOSFIRE spectrograph at the W. M. Keck Observatory. In conjunction with a similar data set we obtained in the range 1 < z < 1.5 with the LRIS spectrograph, we analyze the kinematic and structural properties for 80 quiescent galaxies, the largest homogeneously selected sample to date spanning 3 Gyr of early cosmic history. Analysis of our Keck spectra together with measurements derived from associated Hubble Space Telescope images reveals increasingly larger stellar velocity dispersions and smaller sizes to redshifts beyond z ~ 2. By classifying our sample according to Sérsic indices, we find that among disk-like systems the flatter ones show a higher dynamical to stellar mass ratio compared to their rounder counterparts, which we interpret as evidence for a significant contribution of rotational motion. For this subset of disk-like systems, we estimate that V/σ, the ratio of the circular velocity to the intrinsic velocity dispersion, is a factor of two larger than for present-day disky quiescent galaxies. We use the velocity dispersion measurements also to explore the redshift evolution of the dynamical to stellar mass ratio, and to measure for the first time the physical size growth rate of individual systems over two distinct redshift ranges, finding a faster evolution at earlier times. We discuss the physical origin of this time-dependent growth in size in the context of the associated reduction of the systematic rotation.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Belli, Sirio0000-0002-5615-6018
Newman, Andrew B.0000-0001-7769-8660
Ellis, Richard S.0000-0001-7782-7071
Additional Information:© 2016. The American Astronomical Society. Received 2016 August 2; revised 2016 October 26; accepted 2016 October 29; published 2016 December 27. We thank the referee for a helpful and thorough report. We thank Trevor Mendel and the VIRIAL team for many useful discussions. We also acknowledge Sadegh Khochfar, Eva Wuyts, Alan Meert, and Carlo Nipoti for helpful discussions. We acknowledge Adi Zitrin for completing the observation of one of the MOSFIRE masks. R.S.E. acknowledges support from the European Research Council through an Advanced Grant FP7/669253. The authors recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
Funding AgencyGrant Number
European Research Council (ERC)669253
Subject Keywords:galaxies: evolution; galaxies: formation; galaxies: high-redshift; galaxies: kinematics and dynamics; galaxies: stellar content
Issue or Number:1
Record Number:CaltechAUTHORS:20170104-120608706
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Official Citation:Sirio Belli et al 2017 ApJ 834 18
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73211
Deposited By: George Porter
Deposited On:04 Jan 2017 21:07
Last Modified:03 Oct 2019 16:25

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