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Radio continuum size evolution of star-forming galaxies over 0.35 < z < 2.25
journal contribution
posted on 2023-06-07, 06:35 authored by E F Jiménez-Andrade, B Magnelli, A Karim, G Zamorani, M Bondi, E Schinnerer, Mark Sargent, E Romano-Díaz, M Novak, P Lang, F Bertoldi, E Vardoulaki, S Toft, V Smolcic, K Harrington, S Leslie, J Delhaize, D Liu, C Karoumpis, J Kartaltepe, A M KoekemoerTo better constrain the physical mechanisms driving star formation, we present the first systematic study of the radio continuum size evolution of star-forming galaxies (SFGs) over the redshift range 0.35 < z < 2.25. We use the VLA COSMOS 3 GHz map (noise rms = 2.3 µJy beam-1, ?beam = 0.75 arcsec) to construct a mass-complete sample of 3184 radio-selected SFGs that reside on and above the main sequence (MS) of SFGs. We constrain the overall extent of star formation activity in galaxies by applying a 2D Gaussian model to their radio continuum emission. Extensive Monte Carlo simulations are used to validate the robustness of our measurements and characterize the selection function. We find no clear dependence between the radio size and stellar mass, M?, of SFGs with 10.5 ? log(M?/M?) ? 11.5. Our analysis suggests that MS galaxies are preferentially extended, while SFGs above the MS are always compact. The median effective radius of SFGs on (above) the MS of Reff = 1.5 ± 0.2 (1.0 ± 0.2) kpc remains nearly constant with cosmic time; a parametrization of the form Reff ? (1 + z)a yields a shallow slope of only a = -0.26 ± 0.08 (0.12 ± 0.14) for SFGs on (above) the MS. The size of the stellar component of galaxies is larger than the extent of the radio continuum emission by a factor ~2 (1.3) at z = 0.5 (2), indicating star formation is enhanced at small radii. The galactic-averaged star formation rate surface density (SSFR) scales with the distance to the MS, except for a fraction of MS galaxies (?10%) that harbor starburst-like SSFR. These "hidden" starbursts might have experienced a compaction phase due to disk instability and/or a merger-driven burst of star formation, which may or may not significantly offset a galaxy from the MS. We thus propose to use SSFR and distance to the MS in conjunction to better identify the galaxy population undergoing a starbursting phase. A catalog including the flux and size measurements is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/625/A114
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Publication status
- Published
File Version
- Accepted version
Journal
Astronomy and AstrophysicsISSN
0004-6361Publisher
EDP SciencesExternal DOI
Issue
A114Volume
625Page range
1-20Department 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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