1905.02958.pdf (1.11 MB)
The main sequence at z ~ 1.3 contains a sizable fraction of galaxies with compact star formation sizes: a new population of early post-starbursts?
journal contribution
posted on 2023-06-09, 18:05 authored by A Puglisi, E Daddi, D Liu, F Bournaud, J D Silverman, C Circosta, A Calbrò, M Aravena, Anna Cibinel, H Dannernauer, I Delvecchio, D Elbaz, Y Gao, R Gobat, S Jin, E Le Floc'h, G E Magdis, C Mancini, D A Riechers, G Rodighiero, Mark SargentAtacama Large Millimeter/submillimeter Array (ALMA) measurements for 93 Herschel-selected galaxies at 1.1 = z = 1.7 in COSMOS reveal a sizable (>29%) population with compact star formation (SF) sizes, lying on average >×3.6 below the optical stellar mass (M ?)-size relation of disks. This sample widely spans the star-forming main sequence (MS), having 108 = M ? = 1011.5 M ? and 20 = star formation rate (SFR) = 680 M ? yr-1. The 32 size measurements and 61 upper limits are measured on ALMA images that combine observations of CO(5-4), CO(4-3), CO(2-1), and ? obs ~ 1.1-1.3 mm continuum, all tracing the star-forming molecular gas. These compact galaxies have instead normally extended K band sizes, suggesting strong specific SFR gradients. Compact galaxies comprise the 50 ± 18% of MS galaxies at M ? > 1011 M ?. This is not expected in standard bimodal scenarios, where MS galaxies are mostly steadily growing extended disks. We suggest that compact MS objects are early post-starburst galaxies in which the merger-driven boost of SF has subsided. They retain their compact SF size until either further gas accretion restores premerger galaxy-wide SF, or until becoming quenched. The fraction of merger-affected SF inside the MS seems thus larger than anticipated and might reach ~50% at the highest M ?. The presence of large galaxies above the MS demonstrates an overall poor correlation between galaxy SF size and specific SFR.
History
Publication status
- Published
File Version
- Accepted version
Journal
Astrophysical JournalISSN
0004-637XPublisher
Institute of PhysicsExternal DOI
Issue
L23Volume
877Page range
1-6Department affiliated with
- Physics and Astronomy Publications
Research groups affiliated with
- Astronomy Centre Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2019-06-17First Open Access (FOA) Date
2019-06-17First Compliant Deposit (FCD) Date
2019-06-16Usage metrics
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