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  • 1809.01211v2

    Rights statement: This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: 10.3847/1538-4357/aae822

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Fast and slow paths to quiescence: ages and sizes of 400 quiescent galaxies from the LEGA-C survey

Research output: Contribution to journalJournal article

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  • Po-Feng Wu
  • Arjen van der Wel
  • Rachel Bezanson
  • Anna Gallazzi
  • Camilla Pacifici
  • Caroline M. S. Straatman
  • Ivana Barisic
  • Eric F. Bell
  • Priscilla Chauke
  • Josha van Houdt
  • Marijn Franx
  • Adam Muzzin
  • David Sobral
  • Vivienne Wild
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Article number37
<mark>Journal publication date</mark>20/11/2018
<mark>Journal</mark>The Astrophysical Journal
Issue number1
Volume868
Number of pages20
Publication statusPublished
Early online date16/11/18
Original languageEnglish

Abstract

We analyze the stellar age indicators (Dn4000 and EW(Hδ)) and sizes of 467 quiescent galaxies with M ∗ ≥ 1010 M o at z ∼ 0.7 drawn from DR2 of the LEGA-C survey. Interpreting index variations in terms of equivalent single stellar population age, we find that the median stellar population is younger for larger galaxies at fixed stellar mass. The effect is significant, yet small; the ages of the larger and smaller subsets differ by only <500 Myr, much less than the age variation among individual galaxies (∼1.5 Gyr). At the same time, post-starburst galaxies - those that experienced recent and rapid quenching events - are much smaller than expected based on the global correlation between age and size of normal quiescent galaxies. These coexisting trends unify seemingly contradictory results in the literature; the complex correlations between size and age indicators revealed by our large sample of galaxies with high-quality spectra suggest that there are multiple evolutionary pathways to quiescence. Regardless of the specific physical mechanisms responsible for the cessation of star formation in massive galaxies, the large scatter in Dn4000 and EW(Hδ) immediately implies that galaxies follow a large variety of evolutionary pathways. On the one hand, we see evidence for a process that slowly shuts off star formation and transforms star-forming galaxies to quiescent galaxies without necessarily changing their structures. On the other hand, there is likely a mechanism that rapidly quenches galaxies, an event that coincides with dramatic structural changes, producing post-starburst galaxies that can be smaller than their progenitors. © 2018. The American Astronomical Society. All rights reserved.

Bibliographic note

This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: 10.3847/1538-4357/aae822