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MOSFIRE Absorption Line Spectroscopy of z > 2 Quiescent Galaxies: Probing a Period of Rapid Size Growth

Belli, Sirio and Newman, Andrew B. and Ellis, Richard S. and Konidaris, Nick P. (2014) MOSFIRE Absorption Line Spectroscopy of z > 2 Quiescent Galaxies: Probing a Period of Rapid Size Growth. Astrophysical Journal Letters, 788 (2). Art. No. L29. ISSN 2041-8205.

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Using the MOSFIRE near-infrared multi-slit spectrograph on the Keck 1 Telescope, we have secured high signal-to-noise ratio absorption line spectra for six massive galaxies with redshift 2 < z < 2.5. Five of these galaxies lie on the red sequence and show signatures of passive stellar populations in their rest-frame optical spectra. By fitting broadened spectral templates we have determined stellar velocity dispersions and, with broad-band HST and Spitzer photometry and imaging, stellar masses and effective radii. Using this enlarged sample of galaxies we confirm earlier suggestions that quiescent galaxies at z > 2 have small sizes and large velocity dispersions compared to local galaxies of similar stellar mass. The dynamical masses are in very good agreement with stellar masses (logM_∗/M_(dyn) = −0.02 ± 0.03), although the average stellar-to-dynamical mass ratio is larger than that found at lower redshift (−0.23 ± 0.05). By assuming evolution at fixed velocity dispersion, not only do we confirm a surprisingly rapid rate of size growth but we also consider the necessary evolutionary track on the mass-size plane and find a slope ɑ = d logR_e/d logM_∗ ≳ 2 inconsistent with most numerical simulations of minor mergers. Both results suggest an additional mechanism may be required to explain the size growth of early galaxies.

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
Konidaris, Nick P.0000-0003-1905-2815
Additional Information:© 2014 American Astronomical Society. Received 2014 April 18; accepted 2014 May 12; published 2014 June 3. We thank Chuck Steidel, Ian McLean and their team for their work in producing the remarkable MOSFIRE instrument. We thank Guillermo Barro for useful discussions. The authors acknowledge the very significant cultural role that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
Subject Keywords:galaxies: evolution, galaxies: fundamental parameters, galaxies: high-redshift, galaxies: structure
Issue or Number:2
Record Number:CaltechAUTHORS:20140505-133910034
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Official Citation: MOSFIRE Absorption Line Spectroscopy of z > 2 Quiescent Galaxies: Probing a Period of Rapid Size Growth Sirio Belli et al. 2014 ApJ 788 L29
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45501
Deposited By: Ruth Sustaita
Deposited On:05 May 2014 23:34
Last Modified:03 Oct 2019 06:31

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