J/MNRAS/446/3199 24um fluxes of GOODS-S AGN (Garcia-Gonzalez+, 2015)
Selection of AGN candidates in the GOODS-South Field through
Spitzer/MIPS 24 µm variability.
Garcia-Gonzalez J., Alonso-Herrero A., Perez-Gonzalez P.G.,
Hernan-Caballero A., Sarajedini V.L., Villar V.
<Mon. Not. R. Astron. Soc., 446, 3199-3223 (2015)>
=2015MNRAS.446.3199G 2015MNRAS.446.3199G (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Galaxies, IR ; Photometry, infrared
Keywords: galaxies: active - infrared: galaxies
Abstract:
We present a study of galaxies showing mid-infrared variability in
data taken in the deepest Spitzer/MIPS 24µm surveys in the Great
Observatory Origins Deep Survey South field. We divide the data set in
epochs and subepochs to study the long-term (months-years) and the
short-term (days) variability. We use a χ2-statistics method to
select active galactic nucleus (AGN) candidates with a probability
≤1% that the observed variability is due to statistical errors alone.
We find 39 (1.7% of the parent sample) sources that show long-term
variability and 55 (2.2% of the parent sample) showing short-term
variability. That is, 0.03sources/arcmin2 for both, long-term and
short-term variable sources. After removing the expected number of
false positives inherent to the method, the estimated percentages are
1.0 and 1.4% of the parent sample for the long term and short term,
respectively. We compare our candidates with AGN selected in the X-ray
and radio bands, and AGN candidates selected by their IR emission.
Approximately, 50% of the MIPS (Multiband Imaging Photometer for
Spitzer) 24µm variable sources would be identified as AGN with
these other methods. Therefore, MIPS 24µm variability is a new
method to identify AGN candidates, possibly dust obscured and
low-luminosity AGN, that might be missed by other methods. However,
the contribution of the MIPS 24µm variable identified AGN to the
general AGN population is small (≤13%) in GOODS-South.
Description:
We compiled all the data taken around the GOODS South field with the
MIPS instrument at 24µm by querying the Spitzer Heritage Archive.1
This field was observed by Spitzer during several campaigns from 2004
January to 2007 March. We focused our study on a region around
RA=03:32:36 (J2000) and DE=-27:48:39 (J2000). These data correspond
to different observing proposals from different PI, including the
Guaranteed Time Observations programme (GTO, PI: G. Rieke) and the
GOODS programme (PI: M. Dickinson).
We have obtained 151 AORs (Astronomical Observation Request) but only
downloaded 127 because the others were from the SWIRE (Spitzer
Wide-area InfraRed Extragalactic) survey and were not sufficiently
deep.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tabled1.dat 106 39 Catalogue of the long-term variable candidates
tablee1.dat 99 55 Catalogue of the short-term variable candidates
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See also:
J/A+A/428/1043 : Redshifts from VIMOS VLT Deep Survey (Le Fevre+, 2004)
J/A+A/437/883 : K20 survey: spectroscopic catalogue (Mignoli+, 2005)
J/A+A/449/951 : GOODS-MUSIC sample: multicolour catalog (Grazian+, 2006)
J/ApJS/179/95 : VLA survey of CDF-S. II. (Mainieri+, 2008)
J/A+A/512/A12 : VLT/VIMOS spectroscopy in GOODS-South field (Balestra+, 2010)
Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- ID Identification number
6 A1 --- f_ID [*] *: in the E-CDFS
7- 9 A3 --- n_ID [a,b ] Note (G1)
12- 21 F10.7 deg RAdeg Right ascension (J2000)
23- 33 F11.7 deg DEdeg Declination (J2000)
35- 37 I3 uJy Flux1 Spitzer/MIPS 24um Flux [epoch 1]
39- 40 I2 uJy e_Flux1 rms uncertainty on Flux1
42- 44 I3 uJy Flux3 Spitzer/MIPS 24um Flux [epoch 3]
46- 47 I2 uJy e_Flux3 rms uncertainty on Flux3
49- 51 I3 uJy Flux6 Spitzer/MIPS 24um Flux [epoch 6]
53- 54 I2 uJy e_Flux6 rms uncertainty on Flux6
56- 58 I3 uJy Flux7 Spitzer/MIPS 24um Flux [epoch 7]
60- 61 I2 uJy e_Flux7 rms uncertainty on Flux7
63- 65 I3 uJy <Flux> Mean 24um flux
67- 71 F5.2 --- chi2 Chi2 value
73- 76 F4.1 % Var Measure of the variability
(Var=[(Fmax-Fmin)/]*100)
78- 81 F4.2 --- Rmax Maximum to minimum flux ratio (Dmax/Fmin)
83- 86 F4.2 --- zph ? Photometric redshift
88- 92 F5.3 --- zsp ? Spectrocopic redshift (G2)
94- 98 F5.2 --- R ?=- COMBO-17 R magnitude
100-102 A3 --- Xray? [YES NO] Detected in X-ray ?
104-106 A3 --- Radio? [YES NO] Detected in radio ?
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Byte-by-byte Description of file: tablee1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- ID Identification number
6 A1 --- f_ID [*] *: in the E-CDFS
7- 9 A3 --- n_ID [a,b ] Note (G1)
12- 21 F10.7 deg RAdeg Right ascension (J2000)
23- 33 F11.7 deg DEdeg Declination (J2000)
35- 37 I3 uJy Flux7a Spitzer/MIPS 24um Flux [epoch 7a]
39- 40 I2 uJy e_Flux7a rms uncertainty on Flux7a
42- 44 I3 uJy Flux7b Spitzer/MIPS 24um Flux [epoch 7b]
46- 47 I2 uJy e_Flux7b rms uncertainty on Flux7b
49- 51 I3 uJy Flux7 Spitzer/MIPS 24um Flux [epoch 7]
53- 54 I2 uJy e_Flux7 rms uncertainty on Flux7
56- 58 I3 uJy <Flux> Mean 24um flux
60- 64 F5.2 --- chi2 Chi2 value
66- 69 F4.1 % Var Measure of the variability
(Var=[(Fmax-Fmin)/]*100)
71- 74 F4.2 --- Rmax Maximum to minimum flux ratio (Dmax/Fmin)
76- 79 F4.2 --- zph ? Photometric redshift
81- 85 F5.3 --- zsp ? Spectrocopic redshift (G2)
87- 91 F5.2 --- R ?=- COMBO-17 R magnitude
93- 95 A3 --- Xray? [YES NO] Detected in X-ray ?
97- 99 A3 --- Radio? [YES NO] Detected in radio ?
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Globasl notes:
Note (G1): Notes as follows:
a = in COMBO-17 catalogue and only one counterpart in 2.5" in Rainbow
catalogue
b = only one counterpart in 2.5" in COMBO-17 catalogue
Note (G2): References for spectroscopic redshifts:
ID 5080 :
Grazian et al. (2006A&A...449..951G 2006A&A...449..951G, Cat. J/A+A/449/951)
ID 5109, 4501 :
Mignoli et al. (2005A&A...437..883M 2005A&A...437..883M, Cat. J/A+A/437/883)
ID 7742, 10015, 14779, 2324, 4648, 2847 :
Le Fevre et al. (2004A&A...428.1043L 2004A&A...428.1043L, Cat. J/A+A/428/1043)
ID 2226, 718, 7513 :
Balestra et al. (2010A&A...512A..12B 2010A&A...512A..12B, Cat. J/A+A/512/A12)
ID 13601, 7761 :
Mainieri et al. (2008ApJS..179...95M 2008ApJS..179...95M, Cat. J/ApJS/179/95)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 26-Jun-2015