J/ApJ/875/80 Faint radio sources in GOODS-N and -S. I. VLA 5GHz (Gim+, 2019)
Nature of faint radio sources in GOODS-North and GOODS-South fields.
I. Spectral index and radio-FIR correlation.
Gim H.B., Yun M.S., Owen F.N., Momjian E., Miller N.A., Giavalisco M.,
Wilson G., Lowenthal J.D., Aretxaga I., Hughes D.H., Morrison G.E.,
Kawabe R.
<Astrophys. J., 875, 80 (2019)>
=2019ApJ...875...80G 2019ApJ...875...80G
ADC_Keywords: Radio sources; Surveys; Interferometry; Radio continuum
Keywords: galaxies: active ; galaxies: starburst ; galaxies: star formation ;
radio continuum: general ; surveys
Abstract:
We present the first results from the deep and wide 5GHz radio
observations of the Great Observatories Origins Deep Survey
(GOODS)-North (σ=3.5µJy/beam, synthesized beam size
θ=1.47"x1.42", and 52 sources over 109arcmin2) and GOODS-South
(σ=3.0µJy/beam, θ=0.98"x0.45", and 88 sources over
190arcmin2) fields using the Karl G. Jansky Very Large Array. We
derive radio spectral indices α between 1.4 and 5GHz using the
beam-matched images and show that the overall spectral index
distribution is broad even when the measured noise and flux bias are
considered. We also find a clustering of faint radio sources around
α=0.8, but only within S5GHz<150µJy. We demonstrate that
the correct radio spectral index is important for deriving accurate
rest-frame radio power and analyzing the radio-FIR correlation, and
adopting a single value of α=0.8 leads to a significant scatter
and a strong bias in the analysis of the radio-FIR correlation,
resulting from the broad and asymmetric spectral index distribution.
When characterized by specific star formation rates, the starburst
population (58%) dominates the 5GHz radio source population, and the
quiescent galaxy population (30%) follows a distinct trend in spectral
index distribution and the radio-FIR correlation. Lastly, we offer
suggestions on sensitivity and angular resolution for future
ultra-deep surveys designed to trace the cosmic history of star
formation and AGN activity using radio continuum as a probe.
Description:
Our observations of the Great Observatories Origins Deep Survey
(GOODS)-North (GN) field were conducted in 2011 February and March,
for a total of 22hr at 5GHz in the B-configuration of the VLA under
the program code 10C-225. We observed two fields with the VLA's
Wideband Interferometric Digital Architecture (WIDAR) correlator on
2011 Feb 28, and Mar 10, 15 and 20.
The GOODS-South (GS) field was observed at 5GHz for a total of 15hr
in the A-configuration of the VLA under the project code of 12B-274.
The observations were executed in six different sessions, each with
2.5hr long over six pointings in 2012 Dec 16, 23, 31 and 2013 Jan 1
and 5 (x2).
1.4GHz data are needed to calculate the radio spectral index with our
5GHz data.
For the GN field, we use the deep 1.525GHz imaging data obtained by
Owen+ (2018, J/ApJS/235/34) with rms noise of 2.2uJy/beam and an
angular resolution of 1.6"x1.6" (FWHM). All of our 5GHz sources have a
matching counterpart in the 1.5GHz source catalog.
For the GS field, we use the 1.4GHz VLA data by
Miller+ (2013, J/ApJS/205/13), which has rms noise of ∼6uJy/beam at
the image center with a beam size of 2.8"x1.6". A total of 19 sources
lack a 1.4GHz counterpart; see Section 2.2.1. Throughout this paper,
we analyze only the GS sources that have a unique 1.4GHz counterpart
to avoid the uncertainty introduced by the upper limits.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 81 143 5GHz flux densities and spectral indices of
GOODS-N (GN) and GOODS-S (GS) radio sources
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See also:
J/ApJ/554/803 : New VLA Sky Survey (NVSS) Cat of IRAS 2Jy Galaxies (Yun+ 2001)
J/ApJ/586/794 : Multiwavelength luminosities of galaxies (Bell, 2003)
J/AJ/127/3137 : Hawaii redshifts in the ACS-GOODS region (Cowie+, 2004)
J/ApJS/155/271 : Chandra Deep Field-South: Opt. spectroscopy (Szokoly+, 2004)
J/ApJS/155/73 : Photometric redshifts of X-ray sources in CDF-S (Zheng+, 2004)
J/A+A/437/883 : K20 survey: spectroscopic catalogue (Mignoli+, 2005)
J/A+A/457/517 : ATESP 5 GHz radio survey. I. (Prandoni+, 2006)
J/A+A/451/457 : X-ray properties of AGN in CDFS (Tozzi+, 2006)
J/ApJ/660/167 : Spitzer AGN candidates in CDFN (Donley+, 2007)
J/ApJ/663/81 : SED of hard X-ray selected AGN in XMDS (Polletta+, 2007)
J/A+A/465/1099 : Redshift catalog of 691 objects in CDFS (Ravikumar+, 2007)
J/ApJ/689/687 : GOODS-N spectroscopic survey (Barger+, 2008)
J/ApJS/179/71 : VLA survey of the CDF-S I. (Kellermann+, 2008)
J/AJ/136/1889 : 20cm observations of deep Swire Field (Owen+, 2008)
J/A+A/478/83 : GOODS-South Field VLT/FORS2 redshifts. III. (Vanzella+, 2008)
J/MNRAS/397/281 : Radio imaging in Lockman Hole (Ibar+, 2009)
J/AJ/138/1022 : Emission-line galaxies from HST PEARS survey (Straughn+, 2009)
J/A+A/512/A12 : VLT/VIMOS spectroscopy in GOODS-South field (Balestra+, 2010)
J/ApJS/188/178 : VLA 1.4GHz observations of GOODS-North field (Morrison+, 2010)
J/ApJS/191/124 : Opt. spectroscopy of ECDF-S X-ray sources (Silverman+, 2010)
J/ApJS/187/251 : Ultradeep Ks imaging in the GOODS-N (Wang+, 2010)
J/ApJ/727/1 : IRAC/MUSYC SIMPLE survey (Damen+, 2011)
J/A+A/533/A119 : GOODS-Herschel North and South catalogs (Elbaz+, 2011)
J/A+A/532/A90 : PACS Evolutionary Probe (PEP-DR1) catalogs (Lutz+, 2011)
J/A+A/528/A35 : Infrared luminosity in GOODS fields (Magnelli+, 2011)
J/MNRAS/425/2116 : Arizona CDFS Environment Survey, ACES (Cooper+, 2012)
J/ApJ/759/139 : Herschel+MIPS photom. of GOODS sources (Kirkpatrick+, 2012)
J/MNRAS/421/1644 : 843MHz MOST ATLAS catalogue (Randall+, 2012)
J/ApJS/203/24 : Structural param. of gal. in CANDELS (van der Wel+, 2012)
J/MNRAS/436/3759 : ECDFS sources optical/IR counterparts (Bonzini+, 2013)
J/A+A/549/A63 : GMASS photometry (Kurk+, 2013)
J/ApJS/205/13 : VLA 1.4GHz survey of ECDF-S (DR2) (Miller+, 2013)
J/ApJS/214/24 : 3D-HST+CANDELS catalog (Skelton+, 2014)
J/MNRAS/454/952 : Chandra Deep Field-South ATLAS 5.5GHz DR2 (Huynh+, 2015)
J/AJ/149/178 : Redshift cat. of gal. in GOODS-South field (Morris+, 2015)
J/AJ/150/153 : Team Keck Redshift Survey 2 (TKRS2) (Wirth+, 2015)
J/ApJS/225/27 : 3D-HST Survey: grism spectra master cat. (Momcheva+, 2016)
J/ApJS/224/15 : Improved 2Ms and 250ks Chandra catalogs (Xue+, 2016)
J/MNRAS/471/210 : eMERGE Survey. I. VLA 5.5GHz sources (Guidetti+, 2017)
J/ApJS/228/2 : Chandra Deep Field-South survey: 7Ms sources (Luo+, 2017)
J/A+A/602/A2 : VLA-COSMOS 3 GHz Large Project. II. (Smolcic+, 2017)
J/ApJS/235/34 : Deep JVLA imaging of GOODS-N at 20cm (Owen, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- ID Radio source identifier
(<[GYO2019] GW-NNa> in Simbad)
8- 9 I2 h RAh [3/12] Hour of right ascension (J2000)
11- 12 I2 min RAm Minute of right ascension (J2000)
14- 19 F6.3 s RAs Second of right ascension (J2000)
21- 25 F5.3 s e_RAs [0/0.3] RA uncertainty
27 A1 --- DE- Sign of declination (J2000)
28- 29 I2 deg DEd Degree of declination (J2000)
31- 32 I2 arcmin DEm Arcminute of declination (J2000)
34- 38 F5.2 arcsec DEs Arcsecond of declination (J2000)
40- 43 F4.2 arcsec e_DEs [0/0.22] DE uncertainty
45- 50 F6.1 uJy/beam Spk [14.5/4030]? 5GHz peak flux density
52- 54 F3.1 uJy/beam e_Spk [2.5/6.4]? Spk uncertainty
56- 61 F6.1 uJy Sint [15/9339] 5GHz integrated flux density (1)
63- 66 F4.1 uJy e_Sint [2.9/78.7] Sint uncertainty
68 A1 --- l_alpha Upper limit flag on alpha
70- 75 F6.3 --- alpha [-0.86/1.65]? Radio spectral index (2)
77- 81 F5.3 --- e_alpha [0.001/0.2]? alpha uncertainty
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Note (1): The integrated flux density is the same as the peak flux density
for a point source.
Note (2): The spectral index α is estimated between 1.4 and 5GHz using
1.4GHz images (Owen+ 2018, J/ApJS/235/34, for the GN and
Miller+ 2013, J/ApJS/205/13 for the GS fields) and 5GHz images with
same beam sizes as those of 1.4GHz images.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 07-Sep-2020