J/ApJ/723/1110 MIPS 24um observations of the HDFS (Huynh+, 2010)
MIPS 24 µm observations of the Hubble Deep Field South: probing the IR-radio
correlation of galaxies at z>1.
Huynh M.T., Gawiser E., Marchesini D., Brammer G., Guaita L.
<Astrophys. J., 723, 1110-1118 (2010)>
=2010ApJ...723.1110H 2010ApJ...723.1110H
ADC_Keywords: Photometry, infrared ; Galaxies, IR ; Radio sources
Keywords: galaxies: evolution - galaxies: formation - galaxies: starburst
Abstract:
We present MIPS 24um observations of the Hubble Deep Field South taken
with the Spitzer Space Telescope. The resulting image is 254arcmin2
in size and has a sensitivity ranging between ∼12 and ∼30uJy rms, with
a median sensitivity of ∼20uJy rms. A total of 495 sources have been
catalogued with a signal-to-noise ratio greater than 5σ. The
source catalog is presented as well as source counts which have been
corrected for completeness and flux boosting. The IR sources are then
combined with MUSYC optical/NIR and ATHDFS radio observations to
obtain redshifts and radio flux densities of the sample. We use the
IR/radio flux density ratio (q24) to explore the IR-radio
correlation for this IR sample and find q24=0.71±0.31 for sources
detected in both IR and radio. The results are extended by stacking IR
sources not detected in the radio observations and we derive an
average q24 for redshift bins between 0<z<2.5. We find that the
high-redshift (z>1) sources have an average q24 ratio which is
better fit by local LIRG SEDs rather than local ULIRG SEDs, indicating
that high-redshift ULIRGs differ in their IR/radio properties. So,
ULIRGs at high-redshift have SEDs different from those found locally.
Infrared-faint radio sources are examined, and while nine radio
sources do not have an MIPS detection and are therefore radio-loud
active galactic nuclei (AGNs), only one radio source has an extreme
IRAC 3.6um to radio flux density ratio indicating it is a radio-loud
AGN at z>1.
Description:
The MIPS 24um observations of the HDF-S were carried out over two
campaigns. The first was in 2004 as part of the guaranteed time
observations (GTOs; PI: Fazio) and the second in 2007 Cycle 3
observations (PID 30873, PI: Labbe).
The radio observations of the HDF-S were made between 1998 and 2001
with the Australia Telescope Compact Array using all four available
frequency bands. Between 100 and 300hr of observing at each band
yielded images at 1.4, 2.5, 5.2, and 8.7GHz with maximum sensitivities
of ∼10uJy rms (Huynh et al. 2005, Cat. J/AJ/130/1373; 2007, Cat.
J/AJ/133/1331).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 495 The MIPS 24µm catalog
table4.dat 75 9 Summary of radio Sources that have no MIPS 24um
counterpart and hence are candidate
infrared-faint radio sources
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See also:
J/ApJS/189/270 : MUSYC optical imaging in ECDF-S (Cardamone+, 2010)
J/AJ/135/2470 : Radio observations of the HDFS region. IV. (Huynh+, 2008)
J/AJ/133/1331 : Observation of HDFS at 2.5, 5.2, and 8.7GHz (Huynh+, 2007)
J/ApJ/655/51 : HDFS IRAC observations of 2<z<3.5 galaxies (Wuyts+, 2007)
J/AJ/134/1103 : MUSYC deep near-infrared imaging (Quadri+, 2007)
J/AJ/132/2409 : Deep ATLAS radio observations of CDFS (Norris+, 2006)
J/A+A/452/119 : EIS: infrared observations of CDF-S and HDF-S (Olsen+, 2006)
J/ApJS/162/1 : MUSYC: optical source catalog (Gawiser+, 2006)
J/AJ/130/1373 : Radio observations of the HDFS region. II (Huynh+, 2005)
J/A+A/440/61 : FORS spectroscopy of HDFS galaxies (Rigopoulou+, 2005)
J/AJ/125/1107 : Ultra-deep near-IR observation in HDF-S (Labbe+, 2003)
J/A+A/375/1 : IR observations of CDF + HDF-South (Saracco+, 2001)
J/A+AS/145/111 : HDF-South catalogue of galaxies (Volonteri+, 2000)
J/ApJ/538/493 : HDF-South NICMOS field (Yahata+, 2000)
J/AJ/120/2206 : NTT, HDF-S and HDF-N photometric redshifts (Fontana+, 2000)
J/AJ/120/2747 : HDF-South WFPC2 observations (Casertano+, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- --- [MUSYC_MIPS]
11- 27 A17 --- ID Source identification (JHHMMSS.s+DDMMSS)
29- 38 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
40- 49 F10.6 deg DEdeg Declination in decimal degrees (J2000)
51- 58 F8.1 uJy S24um Spitzer/MIPS 24 micron flux density
60- 63 F4.1 uJy e_S24um Uncertainty in S24um (formal error from APEX)
65- 70 F6.1 --- S/N Signal-to-noise ratio of the source
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- --- [ATHDFS_]
8- 23 A16 --- ATHDFS Radio identification (JHHMMSS.s+DDMMSS) (1)
25- 27 I3 uJy S24um Spitzer/MIPS 24um flux, 5σ limit
29- 33 F5.3 mJy S1.4 ATCA 1.4GHz flux density
35 A1 --- l_S3.6 Limit flag on S3.6
36- 41 F6.2 uJy S3.6 ? Spitzer/IRAC 3.6um flux density (from
Marchesini et al., 2009ApJ...701.1765M 2009ApJ...701.1765M)
42 A1 --- f_S3.6 [cd] not observed with IRAC (2)
44 A1 --- l_q24 Limit flag on q24
45- 49 F5.2 --- q24 IR/radio flux density ratio
(q24=log(S24um/S1.4GHz))
51 A1 --- l_R/IR Limit flag on R/IR
52- 56 F5.1 --- R/IR ? Radio-to-IRAC flux density ratio
(S1.4GHz/S3.6um)
57 A1 --- f_R/IR [cd] not observed with IRAC (2)
59- 63 F5.3 --- zph ? Photometric redshift
64 A1 --- f_zph [b] undetected in optical (2)
66- 70 F5.2 --- alpha ? Radio spectral index (2.5GHz-1.4GHz) from
Huynh et al. (2007, Cat. J/AJ/133/1331) and
S∝να
72- 75 F4.2 --- e_alpha ? alpha uncertainty
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Note (1): Only ATHDFS_J223205.9-603857 is faint enough at 3.6um to meet the
original infrared-faint radio source (IFRS) definition of Norris et
al. (2006, Cat. J/AJ/132/2409). All of these sources have q24 values
suggestive of radio-loud AGNs.
Note (2): Flag as follows:
b = Not detected in MUSYC optical imaging.
c = IRAC image of source has artifacts, so photometry is inaccurate.
d = Out of IRAC coverage.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Jul-2012