J/ApJ/684/136 SEDs of ELAIS-S1 mid-IR sources (Gruppioni+, 2008)
The contribution of AGNs and star-forming galaxies to the mid-infrared as
revealed by their spectral energy distributions.
Gruppioni C., Pozzi F., Polletta M., Zamorani G., La Franca F., Sacchi N.,
Comastri A., Pozzetti L., Vignali C., Lonsdale C., Rowan-Robinson M.,
Surace J., Shupe D., Fang F., Matute I., Berta S.
<Astrophys. J., 684, 136-152 (2008)>
=2008ApJ...684..136G 2008ApJ...684..136G
ADC_Keywords: Energy distributions ; Galaxies, optical ; Redshifts ;
Ultraviolet ; Spectroscopy ; Infrared sources ; Active gal. nuclei
Keywords: cosmology: observations - galaxies: evolution - galaxies: Seyfert -
galaxies: starburst - infrared: galaxies
Abstract:
We present the broadband SEDs of the largest available highly complete
(72%) spectroscopic sample of MIR-selected galaxies and AGNs at
intermediate redshift. The sample contains 203 extragalactic sources
from the 15um ELAIS-SWIRE survey, all with measured spectroscopic
redshift. Most of these sources have full multiwavelength coverage
from the FUV (GALEX) to the FIR (Spitzer) and lie in the redshift
range 0.1<z<1.3. This large sample allows us for the first time to
characterize the spectral properties of sources responsible for the
strong evolution observed in the MIR. Based on SED-fitting, we have
classified the MIR sources, identifying AGN signatures in about 50% of
them. This fraction is significantly higher than that derived from
optical spectroscopy (∼29%) and is due in particular to the
identification of AGN activity in objects spectroscopically classified
as galaxies (the spectroscopic classification may be somewhat
unreliable because of host galaxy dilution in the optical). It is
likely that in most of our objects, the AGN is either obscured or low
luminosity, and thus dominates the energetic output only in the MIR,
showing up just in the range where the host galaxy SED has a minimum.
The fraction of AGNs strongly depends on flux density, with that
derived through the SED-fitting about 20% at S15um∼0.5-1mJy and
gradually increasing to 100% at S15um>10mJy, while that obtained
from optical spectroscopy is never >30%, even at higher flux
densities.
Description:
Our reference sample is the Lari et al. (2001, Cat. J/MNRAS/325/1173)
catalog of 462 sources selected at 15um (LW3 band) in the ELAIS
southern field S1 [centered at 00:34:44.4-43:28:12 (J2000) and
covering about 2x2°]. The multiband SEDs for these sources have
been constructed by looking for counterparts in all the
multiwavelength catalogs from FUV (GALEX) to FIR (ESO Spitzer Imaging
Extragalactic Survey (ESIS, Berta et al. 2006, cat. J/A+A/451/881) and
SWIRE) available in the ELAIS-S1 field.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 157 203 Multiwavelength properties of the 15um sources
in the ELAIS-S1 field (from erratum in
2009ApJ...701..850G 2009ApJ...701..850G)
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See also:
J/MNRAS/325/1173 : ISO ELAIS 15µm survey (Lari+, 2001)
J/AJ/127/3075 : Mid-infrared population of ELAIS-S1 sample (La Franca+,
2004)
J/MNRAS/351/1290 : ELAIS: final band-merged catalogue (Rowan-Robinson+, 2004)
J/MNRAS/358/333 : ELAIS optical ident. at 15um + 1.4GHz (Gonzalez-Solares+,
2005)
J/MNRAS/358/397 : Final analysis of ELAIS 15-µm (Vaccari+, 2005)
J/A+A/451/881 : ESIS BVR catalog, ELAIS-S1 (Berta+, 2006)
J/A+A/476/151 : SWIRE ELAIS-S1 IR-peak galaxy IR fluxes (Berta+, 2007)
J/ApJ/703/1778 : Spitzer sources in SWIRE/XMM/ELAIS-S1 field (Sacchi+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- --- [ELAISC15]
10- 23 A14 --- ELAISC15 ISOCAM name (JHHMMSS+DDMMSS) (1)
24 A1 --- n_ELAISC15 [a-g ] Individual notes (2)
26- 30 F5.1 uJy FFUV ? GALEX FUV flux density (120-177nm)
32- 37 F6.1 uJy FNUV ? GALEX NUV flux density (177-300nm)
39- 44 F6.1 uJy FB ? ESIS B-band flux density
46- 52 F7.1 uJy FV ? ESIS V-band flux density
54- 60 F7.1 uJy FR ? R-band flux density (3)
62- 67 F6.1 uJy FJ ? 2MASS J-band flux density
69- 75 F7.1 uJy FKs ? 2MASS Ks-band flux density
77 A1 --- l_F3.6 Limit flag on F3.6
78- 84 F7.1 uJy F3.6 ? Spitzer/IRAC 3.6um band flux density
86 A1 --- l_F4.5 Limit flag on F4.5
87- 91 I5 uJy F4.5 ? Spitzer/IRAC 4.5um band flux density
93 A1 --- l_F5.8 Limit flag on F5.8
94- 98 I5 uJy F5.8 ? Spitzer/IRAC 5.8um band flux density
100 A1 --- l_F8.0 Limit flag on F8.0
101-105 I5 uJy F8.0 ? Spitzer/IRAC 8.0um band flux density
107-110 F4.1 mJy F15 15um band flux density from Lari et al.,
2001, Cat. J/MNRAS/325/1173
112 A1 --- l_F24 Limit flag on F24
113-116 F4.1 mJy F24 Spitzer/MIPS 24um band flux density
118 A1 --- l_F70 Limit flag on F70
119-124 F6.1 mJy F70 Spitzer/MIPS 70um band flux density
126 A1 --- l_F160 Limit flag on F160
127-132 F6.1 mJy F160 Spitzer/MIPS 160um band flux density
134-138 F5.3 --- zsp Spectroscopic redshift (6)(4)
140-146 E7.3 Lsun LIR Total infrared luminosity (5)
148-152 A5 --- SpCl Optical spectroscopy object type (6)
154-157 A4 --- SEDCl SED-fitting object type (6)
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Note (1): Source name from Lari et al. (2001, Cat. J/MNRAS/325/1173). This
sample, complete at the 5σ level, is the only ISOCAM sample
covering the whole flux density range 0.5-150mJy.
Note (2): Flag as follows:
a = ELAISC15 J003317-431706 was spectroscopically identified through Very
Large Telescope (VLT) VIMOS observations (La Franca et al.,
2007A&A...472..797L 2007A&A...472..797L) and is a R=24.3 galaxy showing [OII] emission at
redshift 0.689.
b = ELAISC15 J003447-432447 was spectroscopically identified through Very
Large Telescope (VLT) VIMOS observations (La Franca et al.,
2007A&A...472..797L 2007A&A...472..797L) and is an AGN2 at redshift 1.076.
c = For ELAISC15 J003915-430426, z-value of 0.013 is from the NED database.
d = For ELAISC15 J003545-431833 we were able to measure z through a more
accurate reduction of the spectrum.
e = ELAISC15 J003330-431553, which was wrongly classified as a starburst
galaxy at z=0.473, showed broad CIII and MgII emission at z=2.170,
typical of AGN1 activity.
f = ELAISC15 J003603-433152, which was classified as AGN2, showed a broad
MgII emission typical of AGN1 activity.
g = ELAISC15 J003622-432826, which was classified as a starburst galaxy,
showed a clear [OIII]/Hβ ratio typical of AGN2 activity.
Note (3): In the area not covered by ESIS (Berta et al. 2006,
Cat. J/A+A/451/881), R magnitudes are from the La Franca et
al. catalog (2004, Cat. J/AJ/127/3075).
Note (4): Three sources with previously poor-quality spectra had their
spectroscopic classification changed after being reobserved with VIMOS
at ESO VLT (La Franca et al., 2007A&A...472..797L 2007A&A...472..797L). See flags e to g
in column f_ELAISC15.
Note (5): Total infrared luminosity; obtained by integrating the best-fitting
SED in the range 8-1000um.
Note (6): Spectroscopic observations of the optical counterparts of the
ISOCAM S1 sources were carried out at the AAT 2dF, ESO Danish 1.5 and
3.6m telescopes, and the New Technology Telescope (NTT) (La Franca et
al. 2004, Cat. J/AJ/127/3075).
The Objects classes are AGN1, AGN2, GAL, ULIG, STB (starburst galaxy),
LINER or UNCL (unclassified).
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 06-Dec-2010