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|Title:||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?||Authors:||PUGLISI, ANNAGRAZIA
Silverman, J. D.
Floc’h, E. Le
Magdis, G. E.
Riechers, D. A.
|Issue Date:||2019||Journal:||THE ASTROPHYSICAL JOURNAL LETTERS||Number:||877||Issue:||2||First Page:||L23||Abstract:||Atacama 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 λ 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.||URI:||http://hdl.handle.net/20.500.12386/30277||URL:||https://iopscience.iop.org/article/10.3847/2041-8213/ab1f92||ISSN:||2041-8205||DOI:||10.3847/2041-8213/ab1f92||Bibcode ADS:||2019ApJ...877L..23P||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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checked on Jun 14, 2021
checked on Jun 14, 2021
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