J/MNRAS/444/846 AKARI NEP Survey sources at 18um (Pearson+, 2014)
The first source counts at 18µm from the AKARI NEP Survey.
Pearson C.P., Serjeant S., Oyabu S., Matsuhara H., Wada T., Goto T.,
Takagi T., Lee H.M., Im M., Ohyama Y., Kim S.J., Murata K.
<Mon. Not. R. Astron. Soc., 444, 846-859 (2014)>
=2014MNRAS.444..846P 2014MNRAS.444..846P
ADC_Keywords: Galaxy catalogs ; Infrared sources
Mission_Name: AKARI
Keywords: galaxies: evolution; infrared: galaxies
Abstract:
We present the first galaxy counts at 18µm using the Japanese
AKARI satellite's survey at the North Ecliptic Pole (NEP), produced
from the images from the NEP-Deep and NEP-Wide surveys covering 0.6
and 5.8deg2, respectively. We describe a procedure using a point
source filtering algorithm to remove background structure and a
minimum variance method for our source extraction and photometry that
delivers the optimum signal to noise for our extracted sources,
confirming this by comparison with standard photometry methods. The
final source counts are complete and reliable over three orders of
magnitude in flux density, resulting in sensitivities (80 per cent
completeness) of 0.15 and 0.3mJy for the NEP-Deep and NEP-Wide
surveys, respectively, a factor of 1.3 deeper than previous catalogues
constructed from this field. The differential source counts exhibit a
characteristic upturn from Euclidean expectations at around a
milliJansky and a corresponding evolutionary bump between 0.2-0.4mJy
consistent with previous mid-infrared surveys with ISO and Spitzer at
15 and 24µm. We compare our results with galaxy evolution models
confirming the striking divergence from the non-evolving scenario. The
models and observations are in broad agreement implying that the
source counts are consistent with a strongly evolving population of
luminous infrared galaxies at redshifts higher than unity. Integrating
our source counts down to the limit of the NEP survey at the 150µJy
level we calculate that AKARI has resolved approximately 55 per cent
of the 18µm cosmic infrared background relative to the predictions
of contemporary source count models.
Description:
The NEP-Deep survey at 18u in the IRC-L18W band is constructed from a
total of 87 individual pointed observations taken between May 2006 to
August 2007, using the IRC Astronomical Observing Template (AOT)
designed for deep observations (IRC05), with approximately 2500 second
exposures per IRC filter in all mid-infrared bands. The deep imaging
IRC05 AOT has no explicit dithering built into the AOT operation,
therefore dithering is achieved by layering separate pointed
observations on at least three positions on a given piece of sky.
The NEP-Wide survey consists of 446 pointed observations
with .300 second exposures for each filter. The NEP-Wide survey uses
the shallower IRC03 AOT optimized for large area multi-band mapping
with the dithering included within the AOT. Note that for both
surveys, although images are taken simultaneously in all three IRC
channels, the target area of sky in the MIR-L channel is offset from
the corresponding area of sky in the NIR/MIR-S channel by ∼20arcmin.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 41 5546 Source catalog for NEP-deep survey
tablea2.dat 41 11889 Source catalog for NEP-wide survey
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See also:
II/297 : AKARI/IRC mid-IR all-sky Survey (ISAS/JAXA, 2010)
II/298 : AKARI/FIS All-Sky Survey Point Source cat. (ISAS/JAXA, 2010)
J/PASJ/59/S529 : NEP deep survey at 11um (Lee+, 2007)
J/A+A/517/A54 : 20cm survey of the AKARI NEP (White+, 2010)
J/ApJS/190/166 : Optical catalog of AKARI NEP-wide survey (Jeon+, 2010)
J/A+A/537/A24 : AKARI NEP-Deep field mid-IR source catalogue (Takagi+, 2012)
J/A+A/548/A29 : IR source catalog of AKARI NEP-Wide field (Kim+, 2012)
J/A+A/559/A132 : AKARI NEP Deep Survey revised catalog (Murata+, 2013)
J/ApJS/207/37 : IR sources spectroscopy in the AKARI NEP (Shim+, 2013)
J/A+A/566/A60 : Optical-NIR catalog of AKARI NEP Deep Field (Oi+, 2014)
J/ApJS/214/20 : AKARI NEP field J- and H- band source catalog (Jeon+, 2014)
Byte-by-byte Description of file: tablea1.dat tablea2.dat
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Bytes Format Units Label Explanations
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1- 11 F11.7 deg RAdeg Right ascension (J2000)
13- 23 F11.8 deg DEdeg Declination sign (J2000)
25- 33 F9.5 mJy S18um [0.06/506] Flux density at 18µm
35- 41 F7.5 mJy e_S18um [0.02/0.6] rms uncertainty on S18um
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 23-Apr-2015