CANDELS: The Progenitors of Compact Quiescent Galaxies at z 2

G. Barro, S. M. Faber, P. G. Pérez-González, D. C. Koo, C. C. Williams, D. D. Kocevski, J. R. Trump, M. Mozena, E. McGrath, A. van der Wel, S. Wuyts, E. F. Bell, D. J. Croton, D. Ceverino, A. Dekel, M. L. N. Ashby, E. Cheung, H. C. Ferguson, A. Fontana, J. FangM. Giavalisco, N. A. Grogin, Y. Guo, N. P. Hathi, P. F. Hopkins, K.-H. Huang, A.~M. Koekemoer, J. S. Kartaltepe, K.-S. Lee, J. A. Newman, L. A. Porter, J. R. Primack, R. E. Ryan, D. Rosario, R. S. Somerville, M. Salvato, L.-T. Hsu

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360 Citations (SciVal)


We combine high-resolution Hubble Space Telescope/WFC3 images with multi-wavelength photometry to track the evolution of structure and activity of massive (M sstarf > 1010 M ☉) galaxies at redshifts z = 1.4-3 in two fields of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. We detect compact, star-forming galaxies (cSFGs) whose number densities, masses, sizes, and star formation rates (SFRs) qualify them as likely progenitors of compact, quiescent, massive galaxies (cQGs) at z = 1.5-3. At z gsim 2, cSFGs present SFR = 100-200 M ☉ yr–1, yet their specific star formation rates (sSFR ~ 10–9 yr–1) are typically half that of other massive SFGs at the same epoch, and host X-ray luminous active galactic nuclei (AGNs) 30 times (~30%) more frequently. These properties suggest that cSFGs are formed by gas-rich processes (mergers or disk-instabilities) that induce a compact starburst and feed an AGN, which, in turn, quench the star formation on dynamical timescales (few 108 yr). The cSFGs are continuously being formed at z = 2-3 and fade to cQGs down to z ~ 1.5. After this epoch, cSFGs are rare, thereby truncating the formation of new cQGs. Meanwhile, down to z = 1, existing cQGs continue to enlarge to match local QGs in size, while less-gas-rich mergers and other secular mechanisms shepherd (larger) SFGs as later arrivals to the red sequence. In summary, we propose two evolutionary tracks of QG formation: an early (z gsim 2), formation path of rapidly quenched cSFGs fading into cQGs that later enlarge within the quiescent phase, and a late-arrival (z lesssim 2) path in which larger SFGs form extended QGs without passing through a compact state.
Original languageEnglish
Pages (from-to)104
Number of pages1
JournalAstrophysical Journal
Issue number2
Early online date21 Feb 2013
Publication statusPublished - 10 Mar 2013


  • galaxies: high redshift
  • galaxies: photometry
  • galaxies: starburst


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