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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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Fast and slow paths to quiescence
T2 - ages and sizes of 400 quiescent galaxies from the LEGA-C survey
AU - Wu, Po-Feng
AU - Wel, Arjen van der
AU - Bezanson, Rachel
AU - Gallazzi, Anna
AU - Pacifici, Camilla
AU - Straatman, Caroline M. S.
AU - Barisic, Ivana
AU - Bell, Eric F.
AU - Chauke, Priscilla
AU - Houdt, Josha van
AU - Franx, Marijn
AU - Muzzin, Adam
AU - Sobral, David
AU - Wild, Vivienne
N1 - 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
PY - 2018/11/20
Y1 - 2018/11/20
N2 - 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.
AB - 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.
KW - galaxies: evolution
KW - galaxies: formation
KW - galaxies: high-redshift
KW - galaxies: stellar content
KW - galaxies: structure
U2 - 10.3847/1538-4357/aae822
DO - 10.3847/1538-4357/aae822
M3 - Journal article
VL - 868
JO - The Astrophysical Journal
JF - The Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 37
ER -