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The SIRTF SWIRE Survey
SWIRE is a shallow/moderate
depth survey of ~70 sq.
degrees in all 7 SIRTF imaging
bands
5 sensitivities:
3.6 m
7.3 Jy
4.5 m
9.7 Jy
5.8 m
27.5 Jy
8.0 m
32.5 Jy
24 m
0.45 mJy
70 m
2.75 mJy
160 m
17.5 mJy
SIRTF is ideally designed for detailed
study of the history of star formation
MIPS is optimized for star-forming
galaxies and AGN
IRAC is optimized for old and/or
reddened stellar populations
SWIRE Science Goals
To enable fundamental studies of cosmology and
galaxy evolution in the Mid- and Far-IR for
0.5<z<2.5:
• Evolution of star-forming and passively evolving
galaxies with time in the context of structure formation
models
• Spatial distribution and clustering of evolved galaxies,
starbursts and AGN, and the evolution of their clustering
• Evolutionary relationship between galaxies and AGN,
and the contribution of AGN accretion energy to the
cosmic backgrounds
SWIRE Survey Design
• The 1<z<2.5 universe is less well studied than the z>3
universe
• Galaxy evolution must be studied
in the context of environment
 SWIRE will sample:
– Several hundred >100
Mpc co-moving volumes
– Redshift range
0.5<z<2.5
– 7 target fields to combat
cosmic variance
The SIRTF SWIRE Survey
Plotting only every 10th galaxy
SFRs for galaxies; compared to integrated SFH (which is normalized by volume)
SWIRE
Simulated Image; Shupe, Fang & Xu
Lockman Hole
(preliminary
pointing)
The Power of the Mid-IR
Gordon et al.
As the 7.7m PAH feature redshifts into the 24m filter
 feature in the predicted f24m< 2mJy counts.
IRAC Observation Plan
For a 10 sq deg area, need 24 AORs for two
coverages
• Each AOR: 1.75º x 30
 6 columns by 21 rows, grid spacing 300
 two cycling dithers at each map grid
point
• Total coverage: 4x30 sec per point
MIPS Observation Plan
• Optimization at 24 and 70m due to confusion
limit at 160m.
• Medium scan rate: 4 second exposures
– 10x redundancy at 24 and 70 microns
– filled 160 m map
• Two epochs
– redundancy
– asteroid/transient removal; destriping
The Importance of Field Selection:
Cirrus/NH/extinction
must be minimized
Schlegel et al. 1998
DIRBE-calibrated IRAS 100m map
B100 Contours
at 1 and 2 MJy/sr
Seb Oliver
|b|=45 contours
SWIRE Field Selection
FIELD
RA
J2000
Dec
ISSA
MJy/sr
E(B-V)
Size
Sq. deg
ELAIS-S1
00h38m30s
-44d00m00s
<0.4
0.008
15
XMM-LSS
02h21m00s
05d00m00s
1.1
0.027
10
Chandra-S
03h32m00s
-28d16m00s
<0.4
0.001
5
Lockman Hole 10h45m00s
+58d00m00s
<0.4
0.006
15
Lonsdale Hole
14h38m00s
+59d15m00s
<0.4
0.012
10
ELAIS-N1
16h13m30s
+55d16m00s
<0.4
0.007
10
ELAIS-N2
16h36m48s
+41d01m45s
<0.4
0.007
5
Sensitivity, Cirrus and Confusion Noise
Table A-2: Expected SWIRE Performance: Noise and Sensitivity
Wavelength
3.6 m
4.5m
5.8 m
8.0 m
24m
70m
160m
Cirrus noise, 1 #
(1 Mjy/sr at 100 m)
18 nJy
40 nJy
60 nJy
300 nJy
2.0 Jy
0.1 mJy
2.0 mJy
Bold: dominant noise term
#
model of Gautier
Extragalactic*
Confusion noise, 1
35 nJy
33 nJy
31 nJy
43 nJy
4.8 Jy
1.3 mJy
19 mJy
SWIRE
photometric
sensitivity, 1
1.4 Jy
1.9 Jy
5.5 Jy
6.5 Jy
0.09 mJy
0.55 mJy
3.5 mJy
* derived from Xu et al. model confusion distribution
Supporting Observations
Optical, NIR:
NOAO, ESO, Palomar, INT, 2dF, Keck
Three Tiers:
r'
25
70 sq deg
g'r'i'Ks 26 / 25 / 24 / 19.5 12+
g'r'i'
27 / 26 / 25
3+
Supporting Observations
Radio: Median predicted flux is 43Jy
Too deep for large area coverage
Selected very deep VLA in small areas:
• 3 @ 3Jy rms
• 3@ 7.5Jy rms
X-ray:
Selection wrt existing/planned deep Xray surveys:
Lockman Hole
Chandra-S
ELAIS
XMM-LSS
Anticipated Early SWIRE Results
BRK magnitude
distributions
observations: Cohen
et al. 2000, Hogg et
al. 2000
ISO 15m sample of
Aussel et al. (1999).
Photometric Redshifts
Examples of Additional Science made possible
• Hundreds of field brown dwarfs, especially T
(“methane”) dwarfs
• 50-60 circumstellar debris disks (to 100 pc), and
HR4796A analogs to 1kpc
•Thermal emission at 8 and 24m from main belt
asteroids as small as 1km
• Serendipitous discoveries; rare objects to 1-in104 to 1-in-106
Identifying SIRTF Sources
Confusion and cirrus noise dominate FIR/submm
observations
 Good complement comes from deep radio surveys to
locate the UV-O-NIR counterparts
– median SWIRE 20cm depth is ~ 75 Jy
– impossible for VLA over large areas
– the Square Kilometer Array can map:
1 sq deg
10 nJy rms, 24 hours
10-30 mas beam
or
1 Jy rms, 2 minutes
14Gyr – galaxy evolution – 2 Gyr
AGN
starbursts
mergers
SWIRE:
– 105-106 galaxies
– 104-105 AGN
large scale structures
– hundreds of 100
Mpc-scale cells
Kauffmann et al
swire