Puglisi, A;
Daddi, E;
Liu, D;
Bournaud, F;
Silverman, JD;
Circosta, C;
Calabro, A;
... Zanist, L; + view all
(2019)
The Main Sequence at z similar to 1.3 Contains a Sizable Fraction of Galaxies with Compact Star Formation Sizes: A New Population of Early Post-starbursts?
The Astrophysical Journal Letters
, 877
(2)
, Article L23. 10.3847/2041-8213/ab1f92.
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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 10^{8} ≤ M_{*} ≤ 10^{11.5) 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_{*} > 10^{11} 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.
| Type: | Article |
|---|---|
| Title: | The Main Sequence at z similar to 1.3 Contains a Sizable Fraction of Galaxies with Compact Star Formation Sizes: A New Population of Early Post-starbursts? |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/2041-8213/ab1f92 |
| Publisher version: | https://doi.org/10.3847/2041-8213/ab1f92 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | galaxies: evolution – galaxies: high-redshift – galaxies: interactions – galaxies: ISM – galaxies: star formation |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10084617 |
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