J/A+A/567/A76 COSMOS field radio-loud AGN population at z>1 (Baldi+, 2014)
The radio-loud AGN population at z > 1 in the COSMOS field.
I. selection and spectral energy distributions.
Baldi R.D., Capetti A., Chiaberge M., Celotti A.
<Astron. Astrophys., 567, A76-76 (2014)>
=2014A&A...567A..76B 2014A&A...567A..76B
ADC_Keywords: Galaxies, radio ; Photometry ; Redshifts
Keywords: galaxies: active - galaxies: high-redshift - galaxies: jets -
galaxies: nuclei - galaxies: photometry
Abstract:
We select a sample of radio galaxies at high redshifts (z>1) in the
COSMOS field by cross-matching optical and infrared (IR) images with
the FIRST radio data. The aim of this study is to explore the high-z
radio-loud (RL) active galactic nuclei (AGN) population at much lower
luminosities than the classical samples of distant radio sources,
which are similar to those of the local population of radio galaxies.
Precisely, we extended a previous analysis focused on low-luminosity
radio galaxies. The wide multiwavelength coverage provided by the
COSMOS survey allows us to derive their spectral energy distributions
(SEDs). We model them with our own developed technique 2SPD that
includes old and young stellar populations and dust emission. When
added to those previously selected, we obtain a sample of 74 RL AGN.
The SED modeling returns several important quantities associated with
the AGN and host properties. The resulting photometric redshifts range
from z∼0.7 to 3. The sample mostly includes compact radio sources but
also 21 FR IIs sources; the radio power distribution of the sample
covers ∼1031.5-1034.3erg/s/Hz, thus straddling the local FR I/FR
II break. The inferred range of stellar mass of the hosts is
∼1010-1011.5M☉. The SEDs are dominated by the contribution
from an old stellar population with an age of ∼1-3Gyr for most of the
sources. However, UV and mid-IR (MIR) excesses are observed for half
of the sample. The dust luminosities inferred from the MIR excesses
are in the range, Ldust∼1043-1045.5erg/s, which are associated
with temperatures approximately of 350-1200K. Estimates of the UV
component yield values of ∼1041.5-1045.5erg/s at 2000Å. The UV
emission is significantly correlated with both IR and radio
luminosities; the former being the stronger link. However, the origin
of UV and dust emission, whether it is produced by the AGN of by star
formation, is still unclear. Our results show that this RLAGN
population at high redshifts displays a wide variety of properties.
Low-power radio galaxies, which are associated with UV- and IR-faint
hosts are generally similar to red massive galaxies of the local FR
Is. At the opposite side of the radio luminosity distribution, large
MIR and UV excesses are observed in objects consistent with
quasar-like AGN, as also proved by their high dust temperatures, which
are more similar to local FR IIs.
Description:
The photometric data used to derive the SEDs of our sources are taken
from the COSMOS survey (Scoville et al., 2007ApJS..172....1S 2007ApJS..172....1S). This
survey comprises ground based, imaging, and spectroscopic observations
from radio to X-rays wavelengths, which covers a 2deg2 area in the
sky.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 112 46 Identified radio galaxies
table2.dat 80 10 Radio galaxies with no clear host identification
table3.dat 92 46 Results from the analysis of the SEDs with 2SPD
table5.dat 86 74 The radio-loud AGN population in the COSMOS field
at z≳1
tablea1.dat 151 46 COSMOS multiwavelength counterparts of the sample
tablea2.dat 92 46 COSMOS GALEX and Spitzer counterparts of the sample
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See also:
J/AJ/128/1974 : The VLA-COSMOS survey (Schinnerer+, 2004)
J/ApJS/172/46 : VLA-COSMOS survey. II. (Schinnerer+, 2007)
J/ApJS/172/70 : zCOSMOS-bright catalog (Lilly+, 2007)
J/ApJS/172/383 : AGN candidates in the COSMOS field (Trump+, 2007)
J/MNRAS/405/2302 : Improved redshifts for SDSS quasar spectra (Hewett+, 2010)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/56] ID number of the object (1)
4- 22 A19 --- RadioID COSMOS-VLA (Large Project) ID number of the
object (Schinnerer et al., 2007, J/ApJS/172/46)
26 I1 --- Nm ? Number of components in case of
multiple objects
27 A1 --- n_RadioID [*] Source from COSMOS-VLA Deep (2)
29- 30 I2 h RAh Right ascension of (one of the components of)
FIRST radio source (J2000)
32- 33 I2 min RAm Right ascension of (one of the components of)
FIRST radio source (J2000)
35- 40 F6.3 s RAs Right ascension of (one of the components of)
FIRST radio source (J2000)
42 A1 --- DE- Declination sign of (one of the components of)
FIRST radio source (J2000)
43- 44 I2 deg DEd Declination of (one of the components of)
FIRST radio source (J2000)
46- 47 I2 arcmin DEm Declination of (one of the components of)
FIRST radio source (J2000)
49- 53 F5.2 arcsec DEs Declination of (one of the components of)
FIRST radio source (J2000)
55 I1 --- Nc Number of matches found in the FIRST catalog
associated with the same radio galaxy
57- 62 F6.2 mJy FFIRST (total) FIRST radio flux of the entire
radio source
64 A1 --- l_FNVSS Limit flag on FNVSS
65- 69 F5.1 mJy FNVSS ? NVSS radio flux
70 A1 --- n_FNVSS [*] objects #12 and 13 are included in the same
NVSS radio source with a flux of 7.6mJy
72- 83 A12 --- MRadio COSMOS-VLA radio morphology
(FR I, FR II, compact or extended)
84- 90 I7 --- HostID ? ID number of the host associated with the
radio galaxy from the COSMOS Intermediate
and Broad Band Photometry Catalog 2008
92 A1 --- l_imag Limit flag on imag
93- 97 F5.2 mag imag ? Subaru i+, CFHT i* or ACS/HST F814W magnitude
of the host galaxy from the the COSMOS
catalog or measured on the image
99-103 F5.3 --- zph ?=- Photometric redshift with 99%
confidence-level errors
105-111 F7.5 --- zsp ?=- Spectroscopic redshift
112 A1 --- r_zsp Reference for zsp (3)
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Note (1): For table2, identification number increasing with the distance from
the center of the COSMOS field.
Note (2): * for objects identified in the COSMOS-VLA Deep Project
(Schinnerer et al., 2004, Cat. J/AJ/128/1974).
The object #34 has the NVSS ID.
Note (3): References for zsp as follows:
a = from the zCOSMOS catalog (Lilly et al., 2007, Cat. J/ApJS/172/70)
b = the Magellan catalog (Trump et al., 2007, J/ApJS/172/383)
c = SDSS quasar (QSO) spectra (Hewett & Wild, 2010, Cat. J/MNRAS/405/2302)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/46] ID number of the object
3 A1 --- n_Seq [*] * for objects excluded from the final sample
for their ambiguous SED properties
4- 9 F6.4 --- z Photometric redshift measured with 2SPD
10 A1 --- n_z [s] s when spectroscopic redshift
12- 16 F5.3 Gyr AgeYSP [0.001/0.04]? Age of the young stellar
population (YSP) at 4800Å rest frame
18- 21 F4.2 mag AVYSP ? Absorption of the young stellar population
(YSP) at 4800Å rest frame
23- 26 F4.1 % fYSP [0/99]? Flux fraction of the young stellar
population (YSP) at 4800Å rest frame
28- 31 F4.2 % fM*YSP ? Mass fraction of the young stellar population
(YSP) at 4800Å rest frame
32- 34 A3 --- QSO [QSO] QSO for spectroscopically-confirmed quasar
36- 39 F4.2 Gyr AgeOSP ? Age of the old stellar population (OSP)
41- 44 F4.2 --- AVOSP ? Absorption of the old stellar population (OSP)
46- 50 F5.2 [Msun] logM* ? Total stellar mass of the galaxy
52- 54 I3 K Tdust ? Effective dust temperature of the first
component
55 A1 --- --- [-]
56- 58 I3 K Tdust2 ? Effective dust temperature of the second
component
60- 64 F5.1 10+9Lsun Ldust ? Dust luminosity of the first component
65 A1 --- --- [-]
66- 70 F5.1 10+9Lsun Ldust2 ? Dust luminosity of the second component
72 A1 --- l_LIRex Limit flag on LIRex
73- 77 F5.2 [10-7W] LIRex ? Infrared excess luminosity defined in the
text (Sect. 6.3)
79 A1 --- l_a8-24 Limit flag on a8-24
80- 84 F5.2 --- a8-24 ? Spectral index α measured on the
infrared excess at 8 and 24um
86 A1 --- l_LUV Limit flag on LUV
87- 91 F5.2 [10-7W] LUV ? UV luminosity at 2000Å in the rest frame
92 A1 --- n_LUV [m] m indicates marginal UV excess
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/46]? ID number of the object
3- 13 A11 --- --- [COSMOS-FR I]
15- 17 I3 --- ID1 [1/285]? COSMOS-FR I name (Chiaberge et al.
2009ApJ...696.1103C 2009ApJ...696.1103C <[CTC2009] NNN> in Simbad)
19- 24 F6.4 --- z Photometric or spectroscopic redshift
25 A1 --- n_z [s] s for spectroscopic redshift
27- 31 F5.2 --- LFIRST FIRST radio luminosity
33 A1 --- l_LNVSS Limit flag on LNVSS
34- 38 F5.2 --- LNVSS ? NVSS radio luminosity
40- 41 A2 --- RCl Radio class (LP or HP for low or high power)
43- 53 A11 --- RMorph Radio morphology based on the VLA-COSMOS images
(FR I, FR II, compact or extended)
55- 57 A3 --- QSO [QSO] "QSO" for spectroscopically-confirmed and
photometrically-defined quasar
59- 63 F5.2 [Msun] logM* ? Total stellar mass of the galaxy
66 A1 --- l_LIRex Limit flag on LIRex
67- 71 F5.2 [10-7W] LIRex ? Infrared excess luminosity defined in the
text (Sect. 6.3)
73 A1 --- l_a8-24 Limit flag on a8-24
74- 78 F5.2 --- a8-24 ? Spectral index measured on the infrared excess
at 8 and 24um
80 A1 --- l_LUV Limit flag on LUV
81- 85 F5.2 [10-7W] LUV ? UV luminosity at 2000Å in the rest frame
86 A1 --- n_LUV [m] m indicates marginal UV excess
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/46] ID number of the object
4 A1 --- l_u*mag Limit flag on u*mag
5- 9 F5.2 mag u*mag CFHT u* magnitude
11- 14 F4.2 mag e_u*mag ? rms uncertainty on u*mag
15 A1 --- n_u*mag [*] our 3"-aperture photometry measure
16 A1 --- l_BJmag Limit flag on Bjmag
17- 21 F5.2 mag BJmag Subaru Bj magnitude
23- 26 F4.2 mag e_BJmag ? rms uncertainty on Bjmag
27 A1 --- n_BJmag [*] our 3"-aperture photometry measure
28 A1 --- l_g+mag Limit flag on g+mag
29- 34 F6.3 mag g+mag Subaru g+ magnitude
36- 39 F4.2 mag e_g+mag ? rms uncertainty on g+mag
40 A1 --- n_g+mag [*] our 3"-aperture photometry measure
41 A1 --- l_VJmag Limit flag on VJmag
42- 46 F5.2 mag VJmag Subaru VJ magnitude
48- 51 F4.2 mag e_VJmag ? rms uncertainty on VJmag
52 A1 --- n_VJmag [*] our 3"-aperture photometry measure
53 A1 --- l_r+mag Limit flag on r+mag
54- 58 F5.2 mag r+mag Subaru r+ magnitude
60- 63 F4.2 mag e_r+mag ? rms uncertainty on r+mag
64 A1 --- n_r+mag [*] our 3"-aperture photometry measure
65 A1 --- l_i*mag Limit flag on i*mag
66- 70 F5.2 mag i*mag CFHT i* magnitude
72- 75 F4.2 mag e_i*mag ? rms uncertainty on i*mag
76 A1 --- n_i*mag [*] our 3"-aperture photometry measure
77 A1 --- l_i+mag Limit flag on i+mag
78- 82 F5.2 mag i+mag ?=- Subaru i+ magnitude
84- 87 F4.2 mag e_i+mag ? rms uncertainty on i+mag
88 A1 --- n_i+mag [*] our 3"-aperture photometry measure
89 A1 --- l_F814W Limit flag on F814Wmag
90- 94 F5.2 mag F814W ?=- HST/ACS F814W magnitude
96- 99 F4.2 mag e_F814W ? rms uncertainty on F814W
100 A1 --- n_F814W [*] our 3"-aperture photometry measure
102 A1 --- l_z+mag Limit flag on z+mag
103-108 F6.3 mag z+mag Subaru z+ magnitude
110-114 F5.3 mag e_z+mag ? rms uncertainty on z+mag
115 A1 --- n_z+mag [*] our 3"-aperture photometry measure
116 A1 --- l_Jmag Limit flag on Jmag
117-121 F5.2 mag Jmag UKIRT J magnitude
123-126 F4.2 mag e_Jmag ? rms uncertainty on Jmag
127 A1 --- n_Jmag [*] our 3"-aperture photometry measure
128 A1 --- l_Kmag Limit flag on Kmag
129-133 F5.2 mag Kmag ?=- CFHT K magnitude
135-138 F4.2 mag e_Kmag ? rms uncertainty on Kmag
139 A1 --- n_Kmag [*] our 3"-aperture photometry measure
140 A1 --- l_Ksmag Limit flag on Kmag
141-145 F5.2 mag Ksmag ?=- NOAO Ks magnitude
147-150 F4.2 mag e_Ksmag ? rms uncertainty on Ksmag
151 A1 --- n_Ksmag [*] our 3"-aperture photometry measure
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/46] ID number of the object
5- 9 F5.2 mag FUV ? GALEX FUV magnitude
11- 14 F4.2 mag e_FUV ? rms uncertainty on FUV
16- 20 F5.2 mag NUV ? GALEX NUV magnitude
22- 25 F4.2 mag e_NUV ? rms uncertainty on NUV
26 A1 --- n_NUV [*] our 3"-aperture photometry measure
29- 34 F6.2 mJy IRAC1 Spitzer/IRAC 3.6um flux
36- 39 F4.2 mJy e_IRAC1 rms uncertainty on IRAC1
40 A1 --- n_IRAC1 [*] our 3"-aperture photometry measure
42- 47 F6.2 mJy IRAC2 Spitzer/IRAC 4.5um flux
49- 52 F4.2 mJy e_IRAC2 rms uncertainty on IRAC2
53 A1 --- n_IRAC2 [*] our 3"-aperture photometry measure
54 A1 --- l_IRAC3 Limit flag on IRAC3
55- 61 F7.2 mJy IRAC3 ?=- Spitzer/IRAC 5.8um flux
63- 66 F4.2 mJy e_IRAC3 ? rms uncertainty on IRAC3
67 A1 --- n_IRAC3 [*] our 3"-aperture photometry measure
69- 75 F7.2 mJy IRAC4 ?=- Spitzer/IRAC 8.0um flux
77- 80 F4.2 mJy e_IRAC4 ? rms uncertainty on IRAC4
81 A1 --- n_IRAC4 [*] our 3"-aperture photometry measure
82 A1 --- l_MIPS Limit flag on MIPS
83- 86 F4.2 mJy MIPS ?=- Spitzer/MIPS 24um flux
88- 91 F4.2 mJy e_MIPS ? rms uncertainty in MIPS
92 A1 --- n_MIPS [*] our 3"-aperture photometry measure
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Oct-2014