J/MNRAS/455/2731 Radio galaxies in ZFOURGE/NMBS (Rees+, 2016)
Radio galaxies in ZFOURGE/NMBS: no difference in the properties of massive
galaxies with and without radio-AGN out to z = 2.25.
Rees G.A., Spitler L.R., Norris R.P., Cowley M.J., Papovich C.,
Glazebrook K., Quadri R.F., Straatman C.M.S., Allen R., Kacprzak G.G.,
Labbe I., Nanayakkara T., Tomczak A.R., Tran K.-V.
<Mon. Not. R. Astron. Soc., 455, 2731-2744 (2016)>
=2016MNRAS.455.2731R 2016MNRAS.455.2731R (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Galaxies, radio
Keywords: galaxies: active - galaxies: evolution - galaxies: high-redshift -
galaxies: stellar content - infrared: galaxies -
radio continuum: galaxies
Abstract:
In order to reproduce the high-mass end of the galaxy mass
distribution, some process must be responsible for the suppression of
star formation in the most massive of galaxies. Commonly active
galactic nuclei (AGN) are invoked to fulfil this role, but the exact
means by which they do so is still the topic of much debate, with
studies finding evidence for both the suppression and enhancement of
star formation in AGN hosts. Using the ZFOURGE (FourStar Galaxy
Evolution) and NMBS (Newfirm Medium Band Survey) galaxy surveys, we
investigate the host galaxy properties of a mass-limited
(M≥1010.5M☉), high-luminosity (L1.4>1024W/Hz) sample of
radio-loud AGN to a redshift of z=2.25. In contrast to low-redshift
studies, which associate radio-AGN activity with quiescent hosts, we
find that the majority of z>1.5 radio-AGN are hosted by star-forming
galaxies. Indeed, the stellar populations of radio-AGN are found to
evolve with redshift in a manner that is consistent with the non-AGN
mass-similar galaxy population. Interestingly, we find that the
radio-AGN fraction is constant across a redshift range of
0.25≤z<2.25, perhaps indicating that the radio-AGN duty cycle has
little dependence on redshift or galaxy type. We do however see a
strong relation between the radio-AGN fraction and stellar mass, with
radio-AGN becoming rare below ∼ 1010.5M☉ or a halo mass of
1012M☉. This halo-mass threshold is in good agreement with
simulations that initiate radio-AGN feedback at this mass limit.
Despite this, we find that radio-AGN host star formation rates are
consistent with the non-AGN mass-similar galaxy sample, suggesting
that while radio-AGN are in the right place to suppress star formation
in massive galaxies they are not necessarily responsible for doing so.
Description:
Our primary data are the pre-release Ks-selected galaxy catalogues
from the FourStar Galaxy Evolution (ZFOURGE) survey (Straatman et al.,
submitted; Spitler et al., 2012ApJ...748L..21S 2012ApJ...748L..21S; Tilvi et al.,
2013ApJ...768...56T 2013ApJ...768...56T; Straatman et al., 2013ApJ...768...56T 2013ApJ...768...56T). This
survey covers the CDF-S (Chandra Deep Field-South) and COSMOS (Cosmic
Evolution Survey) fields (Giacconi et al., 2001ApJ...551..624G 2001ApJ...551..624G;
Schinnerer et al., 2004, Cat. J/AJ/128/1974). Each 11-arcminx11-arcmin
field is imaged at a resolution of 0.6-arcsec down to an
80 per cent Ks band, point source magnitude limit of 24.53 and
24.74ABmag for the CDF-S and COSMOS fields, respectively.
Radio detections in the CDF-S field are determined from the images and
catalogues of the Very Large Array (VLA) 1.4GHz Survey of the
Extended Chandra Deep Field-South: Second Data Release (Miller et al.,
2013, Cat. J/ApJS/205/13).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 126 107 VLA-ZFOURGE sample
tablea2.dat 126 312 VLA-NMBS sample
tablea3.dat 73 39 All VLA sources in COSMOS that have a nearest
neighbour with NMBS useflag = 1
but no Ks neighbour within 1 arcsecond.
tablea4.dat 71 5 All VLA sources in COSMOS that have a nearest
neighbour with ZFOURGE useflag = 1
but no Ks neighbour within 1 arcsecond
tablea5.dat 73 9 All VLA sources in CDFS that have a nearest
neighbour with ZFOURGE useflag = 1
but no Ks neighbour within 1 arcsecond
--------------------------------------------------------------------------------
See also:
II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)
II/253 : Chandra Deep Field South: multi-colour data (Wolf+, 2008)
Byte-by-byte Description of file: tablea1.dat tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Field and ID of the ZFOURGE/NMBS ks-band
object (1)
14- 25 F12.8 deg RAdeg Right ascension (J2000) of the ZFOURGE/NMBS
ks-band object
27- 38 F12.8 deg DEdeg Declination (J2000) of the ZFOURGE/NMBS
ks-band object
40- 44 F5.2 mag Ksmag Ks Band (ZFOURGE/NMBS) apparent magnitude
46- 49 F4.2 --- zphot Peak photometric redshift determined for the
ZFOURGE/NMBS ks-band object
51- 55 F5.2 --- zspec ?=-1 Spectroscopic redshift listed for the
ZFOURGE/NMBS ks-band object (-1 = no data)
57- 61 F5.2 [Msun] logMass Log stellar mass of the ZFOURGE/NMBS ks-band
object
63- 70 F8.2 uJy F1.4GHz 1.4GHz flux of the ZFOURGE/NMBS ks-band object
72- 79 E8.3 W/Hz L1.4GHz 1.4GHz luminosity of the ZFOURGE/NMBS ks-band
object, assumes a spectral index of 0.5
81- 88 E8.3 W/Hz LIR Bolometric IR luminosity of the ZFOURGE/NMBS
ks-band object assuming a Wuyts 2011 average
SED template to extrapolate from 24um fluxes
90- 97 E8.3 W/Hz LUV EAZY interpolated rest-frame 2800Å
luminosity of the ZFOURGE/NMBS ks-band object
99-106 E8.3 Msun/yr SFRRadio SFR from 1.4GHz luminosity of the radio object
108-115 E8.3 Msun/yr SFRUV+IR Combined SFR from LUV and LIR data
117-123 F7.2 --- SFRratio Radio/UV+IR SFR Ratio (≥3.0 are Radio-AGN)
125-126 A2 --- Type [QU SF] Stellar Population type based on
restframe UVJ color color classification (2)
--------------------------------------------------------------------------------
Note (1): COSMOS-NNNNN or CDFS-NNNN in table 1, NMBS-NNNNN in table 2.
Note (2): Stellar Population type as follows:
QU = Quiescent
SF = Star-forming
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat tablea4.dat tablea5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.7 deg RAdeg VLA source right ascension (J2000)
13- 23 F11.7 deg DEdeg VLA source declination (J2000)
25- 30 F6.1 uJy FP1.4GHz 1.4 GHz peak radio flux
32- 35 F4.1 uJy e_FP1.4GHz Error on FP1.4GHz
37- 43 F7.1 uJy IP1.4GHz Integrated 1.4 GHz peak flux
45- 48 F4.1 uJy e_IP1.4GHz Error on IP1.4GHz
50- 53 F4.1 --- RMS Local rms at VLA source position
55- 59 F5.2 mag Kslim Limiting Ks magnitude at the source position
with a zero-point of 25
61- 65 F5.2 arcsec Sep Seperation between VLA radio source and the
nearest Ks-detected object
67- 71 F5.2 mag KsmagNear ?=- Ks magnitude of the nearest Ks-detected
source with a zero-point of 25
73 A1 --- Note Notes (1)
--------------------------------------------------------------------------------
Note (1): Notes as follows:
1 = bright radio object 5"-6" away, radio object may be a sidelobe (psf issue)
of this bright
3 = May be associated with 5-6" away ks-source that has its own (fainter)
radio emission
4 = Extended radio source with core well associated with 2" away ks source
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Jul-2016