J/A+A/625/A114 Star-forming galaxies over 0.35<z<2.25 (Jimenez-Andrade+, 2019)
Radio continuum size evolution of star-forming galaxies over 0.35<z<2.25.
Jimenez-Andrade E.F., Magnelli B., Karim A., Zamorani G., Bondi M.,
Schinnerer E., Sargent M., Romano-Diaz E., Novak M., Lang P., Bertoldi F.,
Vardoulaki E., Toft S., Smolcic V., Harrington K., Leslie S., Delhaize J.,
Liu D., Karoumpis C., Kartaltepe J., Koekemoer A.M.
<Astron. Astrophys. 625, A114 (2019)>
=2019A&A...625A.114J 2019A&A...625A.114J (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Galaxies, photometry
Keywords: galaxies: evolution - galaxies: high-redshift - galaxies: structure -
galaxies: starburst - radio continuum: galaxies
Abstract:
To 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 3GHz map (noise rms=2.3Jy/beam,
θbeam=0.75arcsec) 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)alpha yields a shallow slope of only
alpha=-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 that inferred from
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 ({SIGMA}SFR) scales with the distance
to the MS, except for a fraction of MS galaxies (∼10%) that harbor
starburst-like {SIGMA}SFR. These "hidden" starbursts might have
experienced a compaction phase due to disk instability and/or
merger-driven burst of star formation, which may or may not
significantly offset a galaxy from the MS. We thus propose to use
{SIGMA}SFR and distance to the MS in conjunction to better identify
the galaxy population undergoing a starbursting phase.
Description:
Flux density and size measurements at 3GHz of 3814 radio-selected
star-forming galaxies at 0.35<z<2.25. We report the parameters
originally retrieved with PyBDSF (https://www.astron.nl/citt/pybdsf/)
and those that have been corrected using extensive Monte Carlo
simulations. We recall that the corrected values should be used to
obtain global/statistical trends, given that their reliability might
differ on a galaxy-by-galaxy basis.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
catalog.dat 267 3184 Flux density and size measurements at 3GHz of
3814 radio-selected star-forming galaxies
at 0.35<z<2.25
--------------------------------------------------------------------------------
See also:
J/ApJS/224/24 : The COSMOS2015 catalog (Laigle+, 2016)
Byte-by-byte Description of file: catalog.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right ascension (J2000)
11- 17 F7.5 deg DEdeg Declination (J2000)
19- 24 F6.4 --- z Photometric redshift from the COSMOS2015
catalog; Laigle et al.
(2016, Cat. J/ApJS/224/24)
26- 33 F8.5 [Msun] logMass Stellar mass from the COSMOS2015 catalog,
median of the PDF
35- 42 F8.5 [Msun] E_logMass Upper limit, 68% confidence level, for the
stellar mass
44- 51 F8.5 [Msun] e_logMass Lower limit, 68% confidence level, for the
stellar mass
53- 61 F9.5 --- SNR signal-to-noise ratio
63- 70 F8.6 arcsec DCFWHM Deconvolved FWHM from PyBDSF,
prior correction
72- 79 F8.6 arcsec e_DCFWHM 68% confidence level for DCFWHM,
prior correction
81-102 E22.15 Jy Stot3 Integrated flux density at 3GHz from
PyBDSF, prior correction
104-125 E22.15 Jy e_Stot3 68% confidence level for Stot3,
prior correction
127-136 F10.5 Msun/yr SFR Total SFR (STOT3)=SFR_ir/radio + SFR_UV
138-145 F8.5 Msun/yr e_SFR 68% confidence level for SFR
147-154 F8.6 kpc Reff Effective radius derived from DCFWHM using
the relation: Reff=DCFWHM/2.430; following
Murphy et al. (2017ApJ...839...35M 2017ApJ...839...35M)
156-163 F8.6 kpc e_Reff 68% confidence level for Reff
165-172 F8.6 arcsec DCFWHMc Deconvolved FWHM from PyBDSF,
after correction
174-181 F8.6 arcsec e_DCFWHMc 68% confidence level for DCFWHM,
after correction
183-204 E22.15 Jy Stot3c Integrated flux density at 3GHz from
PyBDSF, after correction
206-227 E22.15 Jy e_Stot3c 68% confidence level for Stot3,
after correction
229-238 F10.5 Msun/yr SFRc Total SFR (STOT3c)=SFR_ir/radio + SFR_UV
240-247 F8.5 Msun/yr e_SFRc 68% confidence level for SFRc
249-256 F8.6 kpc Reffc Effective radius derived from DCFWHMc using
the relation: Reff=DCFWHM/2.430; following
Murphy et al. (2017ApJ...839...35M 2017ApJ...839...35M)
258-265 F8.6 kpc e_Reffc 68% confidence level for REFFc
267 A1 --- Flag [0/1] Flag resolved (1)
--------------------------------------------------------------------------------
Note (1): Flag resolved as follows:
1 = unresolved
0 = resolved
--------------------------------------------------------------------------------
Acknowledgements:
Eric F. Jimenez-Andrade,
ericja(at)astro.uni-bonn.de; jimenezandrade.eric(at)gmail.com
(End) Patricia Vannier [CDS] 26-Apr-2019