Transcript Observations of Near Infrared Extragalactic Background (NIR_EBL)

First stars
and
Near Infrared Extragalactic Background Light
1.
2.
3.
4.
Impact of WMAP
First stars (pop.III) ?
Near Infrared Extragalactic Light(NIR EBL)
Future observations
Sapporo, March 1, 2005
T. Matsumoto (ISAS/JAXA)
Recent topics on Cosmology
WMAP(Wilkinson Microwave Anisotropy Probe）
Launched on June, 2001
Orbit S-E L2
Frequency 23,33,41,61,94 GHz
Polarization can be observed
Angular resolution 0.2 degree
（cf. COBE:7 degree）
First data was opened on Feb.2003
Fluctuation of CMB observed by WMAP
Consistent with COBE
Finer structure is detected
Power spectrum of CMB fluctuation
Positions, heights of peaks provide
cosmological parameters
Geometry of the Universe
Life of the Universe
Baryon, dark matter, dark energy
Hubble constant
Douspis et al.
t~0.17 +/- 0.04
z_rei ~ 20 +/- 8
-----------
Summary of WMAP results
suggesting inflation universe
● Flat universe
Ω=1.04 ± 0.04
● Life of the Universe
134±3 108 yr
● Baryon density
Ωm=0.046 ± 0..02
● Dark matter density
Ωdm=0.23 ± 0.04
● Hubble constant
h=0.72 ± 0.05
● Dark energy
ΩΛ=0.71 ± 0.07
● Optical depth for CMB
τ=0.17 ± 0.04
Constraint on the re-ionization epoch: z〜17
Reionization of the Universe
Gunn-Peterson troughs
-> Absorption by neutral Hydrogen
Fan et al. 2001
t GP ~ 10 (n
5
HI
/ nH )
From Gunn-Peterson troughs in Sloan quasars:
1. Small neutral fractions at z ~ 6 (1% neutral)
2. Sharp transition at z~6 (end of reionization?)
Reionization epoch is earlier than previously thought
What caused reionization?
Super novae
AGN
mini black holes
First stars (Pop.III stars)
Integrated light of first stars can be observed
as near infrared background!
First stars (pop.III stars)?
After the recombination era, universe was neutralized
No metal, H and He only
Cooling through hydrogen molecules
⇨ massive star formation
Luminosity (Eddington limit):
4pG mc2 M/sT ~1.3x1038 M/M○ erg/sec
Temperature
T~104.8-5 K
Life time
tL~eMc2/L~3x106 yr (e~0.007)
Final stage of the evolution
M< 40M○
type II super nova
40M○<M< 130M○
black hole
130M○ <M<260M○
pair instability super nova
M>260M○
black hole
Can we detect the signature of first stars directly?
A 300 M○
first star at z~15,
K-band mag 33
(unlikey to be detectable)
First proto-galaxies
can contain as many
as 105 stars.
(Still not detectable)
Interesting wavelength
range is 1 to 3 microns!!
(Scherrer 2002; Bromm et al. 2002; Santos et al. 2001)
Infrared Extragalactic Background Light (IREBL)
Cosmic Infrared Background (CIB)
integrated light of distant galaxies and stars
UV and optical radiation can be observed at near
Infrared wavelengths due to redshift
A key observation to delineate the dark age of the Universe
Complementary to galaxy deep survey
Space observation is inevitable!
Several rocket flights
COBE/DIRBE
IRTS/NIRS
COBE(COsmic Background Explorer)
• FIRAS
• DMR
• DIRBE(Diffuse Infrared Background Experiment)
Absolute photometry of the sky brightness at
1.25, 2.2, 3.5, 4.9, 12, 25, 60, 100, 140, 240 mm
beam size ~0.7 degree
COBE was launched on 1989 and attained all sky survey.
As for the CIB,COBR team reported
detections at far infrared bands
upper limits for other bands
Several authors obtained significant detections at J, K, L
bands using COBE data
IRTS(Infrared Telescope in Space)
One of mission instruments of
small space platform, SFU
launched on March 15, 1995
15cm cold telescope
Optimized for diffuse
Extended sources
Mission life ~ 1 month
NIRS(Near Infrared Spectrometer)
One of 4 focal plane instruments of IRTS
wavelength coverage
spectral resolution
beam size
1.4-4.0 mm
0.13
mm
8 arcmin. x 8 arcmin.
Compared with COBE/DIRBE
smaller beam
capability of the spectroscopy
smaller spatial coverage
~7% of the sky
Near Infrared Sky
Foreground emission sources
• zodiacal light
scattered sunlight by
interplanetary dust (IPD)
• zodiacal emission
thermal emission from IPD
l>3.5mm
• Milky Way, integrated star light
・It is important to resolve and remove as
faint stars as possible.
・Smaller beam is better to avoid confusion
IRTS/NIRS:
8 arcmin
COBE/DIRBE:
0.7 degree
Subtraction of foreground emission
Is a critical issue to detect EBL
IRTS observations
7% of the sky was surveyed during IRTS observation period (4 weeks)
The data for 5 days before liq. He ran out were used to avoid contamination
The data at high galactic latitudes are sampled
40<b<58 degree, 10<b<70 degree
spectra of 1010 blank skies where no stars are detected
effective beam size is 8’x20’ due to scanning effect
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Integrated light of faint stars
Constructed logN/logS model based
on the NIRS observation (M.Cohen)
Calculated integrated light of stars
fainter than cut off magnitudes
for b=42, b=45, b=48 and applied
cosec(b) law
The result is consistent with 2MASS
For the H and K bands
-1
.sr )
mm)
40
-2
cf. 10.4 mag. at 2.24 mm
2MASS(H) and model(1.63
45
Surface brightness (W.m
Obtained magnitudes of stars that
correspond to the noises
→ cut off magnitudes for all
wavelength bands
50
35
30
25
20
15
2MASS(K) and model( 2.14 mm)
10
1.3
1.35
1.4
1.45
cosec(b)
1.5
1.55
Zodiacal light and emission
Apply physical model by Kelsall et al.
(ApJ, 508, 44 1998) to NIRS bands.
Model is based on the annual variation
of the zodiacal light observed by
DIRBE/COBE.
Calculate the brightness of zodiacal
light/emission for all NIRS bands and
observed points.
After subtracting the star light and zodiacal light/emission
Significant isotropic emission was detected for all bands !
Ch22,1,63 mm
700
600
500
-2
.sr
-1
)
observed_sky - star_light
Surface brightness (W.m
400
300
zodiacal light
200
100
0
residual emission
-100
10
20
30
40
50
b, ecliptic latitude (degree)
60
70
80
Residual emission shows no dependence on the galactic plane
Breakdown to emission components
Surface brightness (W .m
-2
.sr
-1
)
10-6
Observed sky brightness at high ecliptic latitude
10-7
Zodiacal light/emission
Isotropic emission
10
~20 % of dark sky
-8
Integrated light of faint stars
2
Waveleng th (
3
mm)
4
COBE/DIRBE and star counts
Comparison with other observation
J-band
K-band
Dwek & Arendt (1998)
9.9 ±2.9
Gorjian et al. (2000)
22.4±6
30.7±6
Wright and Reese (2000)
Wright (2001)
Cambresy
IRTS/NIRS
L-band
23.1±5.9
31.4±5.9
28.9 ±16.3
61.9 ±16.3
54 ±16
20.2±6.3
28.5 ±6.3
27 ±6.7
27±5
（2.24 mm)
In unit of nW.m-2.sr-1
Red numbers are based on "very strong no-zodi principle" (VSNZP)
All observations are consistent if same zodi model is used!
11.0 ±3.3
15.4 ±3.3
16.8 ± 3.2
Spectrum of the observed isotropic emission
IRTS/ NIRS
Totani et al. 20 01
COBE/DIRBE
Stellar like spectrum was found.
Madau and Pozettti 2000
Wright and Ree se 2 000
, Kels all model
Cambrecy 200 1
Fazio et al. 200 4
Model by Totani e t al. 2 001
Bernstein e t al. 2 002
Main error is uncertainty of the
zodiacal light model
Significantly brighter than the
integrated light of galaxies !
Spectral gap around 1mm
In-band energy flux is
~ 35 nW.m-2.sr-1
-1
･sr )
Surface brightness (nW･m
-2
Consistent with COBE/DIRBE
100
10
0.2
0.4
0.6
0.8
1
Wavelength ( mm)
3
5
Spectrum of excess emission over ILG can be explained well
by integrated light of first stars!
Model by Salvaterra and Ferrara
Bernstein et al. 2002
NIRS/IRTS
Cambresy et al. 2001
Wright and Reese 2000
Surface brightness (W.m
-2
-1
.sr )
100
10
0.5
0.6 0.7 0.8 0.9 1
2
W avelength (mm)
3
4
Sarvaterra and Ferrara
(MN 339, 973 (2003)
zend~8.8, redshifted Lya -> J band
f★=10〜50％
massive star formation
-> produced metals were confined in
black holes
z=17
2.2x108 yr
z=8.8 5.5x108 yr
Another evidence of NIR EBL
Inverse process of pair anihiration
g (E~TeV) + g (e~eV) -> e+ + ewhen Ee>(mc2)1/2
Cross section is maximized when the soft phton energy is
e~2(mc2)2/E=0.5(1 TeV/E) eV ~2mm
Absorption of TeV-g blazer!
BL Lac object
H1426+428
z=0.129
■ CAT(1998-2000)
▲ Whipple(2001)
● HEGRA(2002)
○ HEGRA(2002)
lines:
model by
Mapelli and Ferrara
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Fluctuation of the sky -1
rms fluctuation
b>47, observed_fluc
SL_nominal
Surface brightness of the sky fluctuation (W.m
-2
-1
.sr )
2MASS stars
Read out noise
photon noise
Stellar fluctuation is estimated by using the
model, but consistent with 2MASS
10
Fluctuation of zodiacal emission at 12mm is
less than 1% (IRAS, COBE, ISO)!
⇨ Zodiacal light can not explain observed
sky fluctuation!
1
2
W avelength ( mm)
3
4
Fluctuation of the sky -2
Correlation between wavelength bands
4 10 -8
)
-1
3 10 -8
mm ( W.m
2 10 -8
Surf ace brightness a t 2.24
-2
.sr
Clear correlation between
wavelength bands was
detected.
Spectrum (color) of
fluctuation component is
similar to that of isotropic
emission
y = 4.5368e-12 + 0.51344x R= 0.74258
0
1 10
-1 10
-8
⇨ Isotropic emission is
spatially fluctuating
-8
-2 10 -8
-3 10
-8
-4 10 -8
-8
-6 10
-4 10
-8
-2 10
-8
0
Surf ace brightness a t 1.83
2 10
-8
mm ( W.m
4 10
-2
.sr
-8
-1
)
6 10
-8
Spectrum of fluctuation
10
⇨ Excess emission is
)
-1
DIRBE/COBE
10
EBL
Surface brightness (W.m
-2
.sr
fluctuating keeping the
similar spectrum!
Excess emission over ILG
Excess sky
fluctuation
1
color of flutuating
component
Observed rms fluctuation:
~5% of the sky brightness,
~6% of the zodiacal light,
~20% of the isotropic
emission
Nearest pop.III stars (z~8.8)
are responsible for the
fluctuation!
1
2
Wavelength ( mm)
3
4
What causes NIREBL fluctuation?
1. Stellar fluctuation?
Model is fairly consistent with 2MASS data!
2. Zodiacal light and/or emission?
IRAS, COBE, ISO
3. Faint galaxies?
4. Pop.III stars?
Zodiacal emission is very isotropic!
IRAS: 0.5 degree beam at 15 and 25 mm
COBE: 0.7 degree beam at 12, 25 and 60 mm
ISO: 3’x3’ pixel, 45’x45’ frame
5 fields at different b were observed at 25 mm
10-5
Surface brightness (W.m -2 .sr-1 )
Residual from smooth distribution is less than
1% of peak brightness!
Spectrum of the zodiacal light and emission
( b<10 degree)
280K
blackbody
solar spectrum
10-6
MIRS
NIRS
10-7
rms fluctuation in one field is ± 0.2% !
1
10
Wavelength ( mm)
Observed fluctuation is 6% of ZL
It is unlikely there exists big difference between scattering and emission
Observations (DIRBE, IRTS/NIRS and NITE) and
theory (Cooray et al. 2004)
Can pop.III explain observed
Fluctuation?
model brightness
9<z<10
10<z<11
11<z<12
12<z<13
13<z<14
(Salvaterra and Ferrara 2004)
-1
-2
model surface brightness (W.m
z-dependence of the
model brightness
.sr )
100
10
1
2
Wavelength (mm)
3
4
2-point correlation function
IRTS / NIRS
30
20
Analysis is made for wide band brightness
(integrated brightness for 1.43-2.14mm)
Read out noise is negligible
Fluctuation is celestial origin
0
-10
-20
Correlation amplitude, C() (nW.m -2.sr r-1 )
Data points lie along the belt
↓
One dimensional analysis
60
55
b (galactic latitude, degree)
10
2MASS
30
20
10
0
-10
-20
Random simulation
30
20
50
↑
10
0
45
-10
-20
40
60
80
100
120
140
160
l (galactic longitude, degre)
Observed sky
180
200
0
2
4
6
Angular distance,  [degree]
8
10
Power spectrum
100
Specific feature at 1〜2 deg.
This scale is,
20 Mpc at z=8.8
200 Mps at present
10
Angular spectrum,
√{qP(q)}
[nW.m -2 .sr
-1
]
IRTS / NIRS
2MASS
Random simulation
1s upper limit
First peak of CMB
(l~220, 0.8 deg)
corresponds to
1.45 deg. at z~8.8
1
0.1
1
Angular frequency,
q [1/deg]
Power spectrum
for subsections
Power spectrum, {qP(q)}1/2 [nWm-2sr-1]
A ( l < 134)
B ( l > 134)
10
1
0.1
1
Spatial frequency, q [1/deg]
Expected fluctuation and detection capability of IRC/ASTRO-F
(Cooray et al. 2004, Ap.J, 606, 611)
⌒
Theory:
Based on the fluctuation of
dark matter.
Observation:
Much larger fluctuation
Sharp peak at 2 deg.
Radiation of pop.III stars do
not follow dark matter?
Underlying fluctuation may
exists.
Future observations:
Subtraction of foreground
galaxies is essentail.
ASTRO-F is powerful
Theoretical estimation of fluctuation
Kashlinsky et al. 2004
Surface brightness (nW･m -2･sr -1)
100
Future observations
Issues to be observed
10
• Spectral shape
Confirmation of the spectral gap at ~1mm real?
Other spectral features?
0.2
0.4
0.6
0.8
1
3
5
Wavelength ( mm)
-1
.sr )
2MASS stars
b>47, observed_fluc
Read out noise
Photon noise
Star light, model
Surface brightness of the sky fluctuation (W.m
-2
• Fluctuation
Spatial correlation over the wide range of angular scale
Confirmation of 2 degree feature in 2 dimensional image
Observe underlying large scale structure
• Absolute measurements
Observation free from ambiguity of the model ZL
10
1
2
3
4
W avelength ( mm)
ASTRO-F: image at K and L
100
]
-1
[nW.m -2 .sr
√{qP(q)}
Out of zodiacal cloud mission: zodi free observation
IRTS / NIRS
2MASS
Random simulation
1s upper limit
10
Angular spectrum,
CIBER (Rocket experiment): spectral observation,
image at I and H
1
0.1
1
Angular frequency,
q [1/deg]
ASTRO-F
Formation and evolution of galaxies, stars, and planets
First dedicated infrared mission of ISAS
70cm cooled infrared telescope
Advanced Infrared Survey
50 times higher sensitivity,
10 times better spatial resolution,
has longer wavelength band,
than IRAS
Instruments
IRC(Infrared Camera)
512x412 InSb array camera, 1.5”/pixel
band imaging: K, L, and M bands
low resolution spectroscopy: R-30 slit 2x50 pixel, R-15 4x50 pixel
256x256 SiAs array
FIS(Far Infrared Surveyor)
Launch target : January, 2006
Orbit : sun synchronous orbit, 750km altitude
Mission life: ~1.5 year (liq. He holding time)
+ 2 years (dedicated to NIR Observations)
Observation of NIREBL with ASTRO-F
Advantages of IRC/ASTRO-F observation
• Point-source rejection by high-resolution imaging observation
Limiting magnitude at the K band is ~20 mag. for one pointing observation (~10 min.)
This corresponds to ~30 nW m-2 sr-1 for 1 pixel (5s)
Almost all galactic stars and faint galaxies can be identified
• Discrimination of the fluctuation of the zodiacal light
Observation of the same field at the different time epoch
• Spitzer does not have K band
Observation plans
1. Detection of the NIREBLfluctuation over the wide range of angular scale
Wide area survey towards north ecliptic pole (NEP) is being proposed.
Coordination with galaxy deep survey group
2. Detailed study of the spectrum of IREBL
Low resolution spectroscopy at different ecliptic latitudes (2~5mm)
Spectrum without contamination of stars and galaxies can be obtained
“NEP-Deep & Wide” : Summary
Revised on 28th Oct. 2004
NEP-Deep Field, 50 pointing/FOV 0.5 deg2
NEP-Wide Field, 4 pointing/ FOV
Area: 2.8
deg2
2.8 deg
N2
N3 or N4
2
2
S7
S11
2
2
L15
L24
2
2
ASTRO-F detection limit
Wide(1pixel) 5s
Spectroscopy
(100pixels
x 10sky) 5s
Deep(1pixel) 5s
Wide(100pixels) 5s
K >20mag
Integrated flux
of galaxies
• IRC imaging observations at NEP are enough sensitive to detect the CNIRB
fluctuation seen by IRTS
• Spectroscopic measurement of the CNIRB mean level avoiding the contamination
by normal galaxies
Expected fluctuation and detection capability of IRC/ASTRO-F
(Cooray et al., submitted to Ap.J.)
CIBER: Cosmic Background Explorer
Objectives
Sounding rocket observations at the wavelengths below the K band!
NASA’s Black Brandt rocket
1. Spectrometer: Confirmation of spectral gap at ~1mm
low resolution spectroscopy, 0.8mm<l<2.0mm
Surface brightness (nW･m -2･sr -1)
100
10
0.2
0.4
0.6
0.8
1
3
Wavelength ( mm)
2. Imager: Observation of sky fluctuations at the I and H bands
2-dimension analysis
100
10
Angular spectrum,
√{qP(q)}
[nW.m -2 .sr
-1
]
IRTS / NIRS
2MASS
Random simulation
1s upper limit
1
0.1
1
Angular frequency,
q [1/deg]
5
Instrumentation of CIBER
Spectrometer
7.3 cm dia. Telescope
1 arcmin./pixel, 4 degree frame
low resolution spectroscopy
0.8-2.0mm, R~10
Imager
15 cm dia. Telescope x2
10 arcsec/pixel, 2.8 degree frame
I and H
Optical design of the spectrometer
Optics
13 lenses & 1 prism
linear dispersion
multiple slits (4 apertures)
Aperture
73.3
F-number
F/2
mm
FOV
4x4
degrees
Pixel FOV
1x1
arcmin
Slit size
1x256
arcmin
Wavelength
l = 0.85~2.00
Spectral resolution
ll = 21~23
Optical efficiency
0.8
Focal plane array
256 x 256 HgCdTe
Operating temperature
77
Quantum efficiency
0.5
Dark current
Readout noise (CDS)
< 0.1
10
mm
K
e-/s
e-
Photo current (dark sky)
10~20
e-/s
Photon noise (t=15s)
12~17
e-
Limiting mag (15s, 3s)
J = 15.0
Imager Optics
Aperture
15
cm
Pixel size
10
arcsec
FOV
l
2.8 x 2.8
degrees
mm
0.95 (I)
1.6 (H)
l l
0.5
0.5
Optical
0.3
0.5
23
32
e-/s
< 0.03
< 0.03
e-/s
RN (C DS)
< 10
<10
e-
I (sky)
800
390
nW m-2 sr-1
I inst.
18/pix (1s)
7/pix (1s)
nW m-2 sr-1
I conf.
8/pix (1s)
5/pix (1s)
nW m-2 sr-1
I total
20/pix (1s)
9/pix (1s)
nW m-2 sr-1
1e3
6e3
#/sq degree
0.8 %
5%
pixel loss
140 (s)
120 (s)
mJy
18.0 (s)
17.5 (s)
Mag
efficiency
Photo
current
Dark current
galaxy cut
F total
Detection limit of the spectrometer
Surface brightness lIl [nW/m2/sr]
ZL
ZE
100
1 pixel, 15s, 1s
IREB brightness
HST
10
4 x 4 pixels, 50s, 1s
1s fluctuation
400 pixels, 15s, 1s
1
0.5
0.6 0.7 0.8 0.9 1
2
Wavelength l [mm]
3
4
Simulated spectrum of the sky
1.4 103
EBL fit
b=10
1.2
ZL(90)+EBL
.sr
-1
)
ZL(10)+EBL
103
-2
IRTS
HST
Surf ac e Bri ghtness (nW.m
1 103
8 102
b=90
6 102
4 102
2 102
0 100
0.8
1
1.2
1.4
Wavelength [um]
1.6
1.8
2
Expected performance of the imager
Spatial power spectrum of Pop III fluctuations (red curves), local galaxy fluctuations (correlations term light blue
curves, shot term dashed curves) for 3 different cutoff magnitudes, and the total signal (solid blue curves). The
18.5 mag cutoff is for the rejection level from the NAME images alone; the faintest cutoff (I = 25.5 and H = 21)
comes from ground-based measurements overlapping our images. The data points show the errors from NAME in
a 100 s observation, including both instrument noise and sample variance. We assume there are no Pop III
fluctuations detectable at I-band, following the IRB star spectrum in Fig. 3. NAME can easily detect the optimistic
Pop III signal (this model produces a cumulative background of 25 nW m-2 sr-1, consistent with the missing amount
in Figs. 1 and 3), clearly distinguished by its different power spectrum from local galaxies at H-band. NAME has
sufficient sensitivity to detect the pessimistic Pop III signal (this model produces a background of 3 nW m-2 sr-1),
although it is obscured by local galaxy fluctuations at a limiting magnitude of H = 21. Reducing the cut-off
magnitude further is possible, and would allow us to positively extract even the signal of the pessimistic model.
Configuration of the telescope system
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Payload configuration
Observation plan
Fig. 17. Proposed sequence of observations superposed on the trajectory of the NITE payload. Separation from the
rocket engine occurs at 85 s, followed by despin, opening of the vacuum shutter door at 95 s, and slewing the payload
to the first science target. The instrument observes 5 science fields before closing the shutter door, reentry into the
atmosphere, and recovery operations
Organization and schedule
Organization
Japan:
US:
Korea:
ISAS(Matsumoto, Matsuura, Wada, Matsuhara)
Nagoya U. (Kawada, Watabe)
Caltech/JPL(J.Bock)
UCSD (B.Keating)
KAO (S. Pak, D-H. Lee)
Schedule
June, 2004
Spring, 2007
Spring, 2008
Funding?
Proposal to NASA
Now approved!
No-funded launch!
First launch at White Sands
Second launch
The life of an IR rocket
(Jamie’s previous experiment)
Solar sail mission
Out of zodiacal cloud mission
● Free from ZL and IPD emission
● Accurate absolute measurement of EBL
without IPD model ambiguity is possible
● Observation of the mid-infrared
background is possible
Free from zodiacal light/emission
provides decisive result for the NIREBL!
Possible mission concept of out of zodiacal cloud mission!
Scientific objectives
Accurate measurement of
spectrum and fluctuation of IREBL
Instrumentation
Telescope
Wavelength range
Pixel FOV
Detector
Cooling system
Weight
5cm dia. lens system
0.8-2.2mm
~10’
HgCdTe
radiation cooling
3 kg
Summary
1.
CMB polarization observed by WMAP indicates that the Universe was
reionized at z~17 by the first massive stars (pop.III stars).
2.
Independent observations by COBE and IRTS provide detections of
significant near infrared extragalactic background light. Recent
observations of Tev-g Blazers support its cosmological origin.
3.
The near infrared extragalactic background observed by IRTS and COBE
could be consistent with pop.III star scenario.
4.
Spectrum observed by IRTS suggests the redshift at the end of pop.III
era is ~9.
5.
Fluctuation of the sky was detected (~20% of EBL) by IRTS and COBE
which is too large to be explained with the standard model.
6. Near infrared background is a unique tool to investigate the pop.III stars.
ASTRO-F, CIBER(Rocket experiment) and Solar-Sail missions will
provide valuable information on the pop.III era.
NIREBL is a unique tool to investigate the first stars!
CMB
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z=1,000
?
3x105 year
Near infrared background
z~10
5x108 year
Cosmic Microwave Background
(CMB)
Most distant observable object
The Universe ~4x105 years after big bang
Fossil photons
COBE(COsmic Background Explorer) CMB Map
(launched on 1989 by NASA)
CMB is very uniform
But
Fluctuation of ~10-5 is detected ⇨
Present Universe
Extremely non uniform!
Large scale structure, Cluster of galaxies, galaxies, stars
planets, -------
Evolution from uniform and isotropic Universe to extremely non uniform Universe?
How first stars and galaxies formed?
Evolution of the Universe
Dark age of the Universe
Proposed Survey Field
Prepared by N. Fujishiro
IRC background measurements around NEP
1. Wide-band deep imaging in K, L and / or M bands
Spectral
resolution
l/l
Survey area
[sq.degree]
Exposure time per
frame
[# of pointings]
Single pixel
detection limit
(5s) *
[nW/m2/sr]
Number of
galaxies per
camera frame**
Number of
dark pixels
per frame ***
Ultra-Wide
(Phase-3)
3
100
TBD
~ 10
(pixel binning)
-
-
Wide
3
2.8
2 (500 s)
10
-
-
Deep
3
0.5
25 (1.4 hrs)
3
3000
>10^5
Ultra-Deep
3
-
-
-
-
-
* in unit of surface brightness (lIl)
** FOV of the IRC camera frame is 10’x10’
*** number of pixels available for the background analysis = total number of pixels – (confusion factor) x (number of galaxies)
= 1.7x10^5 – (3pics x 3pics) x (number of galaxies)
2. Spectroscopy
Spectroscopy
Spectral
resolution l/l
Survey area
Exposure time
Detection limit (5s)
[nW/m2/sr]
Number of
galaxies
Number of
dark pixels
30
(l = 2 – 5 mm)
3” x 73”
x 100 directions
(various b and b)
1 pointing (500 s)
x 100 directions
30 (pixel binning)
~10 (10 sky average)
2
90
Ratio to the ZL model
1.4
1.3
1.2
1.1
1
0.9
1
1.5
2
2.5
3
Wavelength (mm)
3.5
4
4.5
Lensed galaxy at z~10?
Pello et al. 2004, A&A 416, L35-L40.
SED and spectrum
IRC SURVEY STRATEGIES
Depth and Area
Number of Pointings
100
10
1
Area (sq. deg.)
Theory to Reality: Near-IR wide-field surveys
(planned)
5-sigma
point
source
detection
(experiments at this end are preferred)
IRC background measurements around NEP
1. Wide-band deep imaging in K, L and M bands
Spectral
resolution
l/l
Survey area
[sq.degree]
Exposure time per
frame
[# of pointings]
Single pixel
detection limit
(5s) *
[nW/cm2/sr]
Number of
galaxies per
camera frame**
Number of
dark pixels
per frame ***
Wide-field Shallow
（phase-3)
3
100
1 (500 s)
30
2x10^3
>1.5x10^5
Shallow (Phase-1,2)
3
10
1 (500 s)
30
2x10^3
>1.5x10^5
Deep (Phase1,-2)
3
1
10 (1.4 hrs)
10
(3-4)x10^3
>1.3x10^5
Ultra Deep
(Phase-1, 2)
3
0.02
100 (14 hrs)
3
(0.5-1)x10^4
>8x10^4
* in unit of surface brightness (lIl)
** FOV of the IRC camera frame is 10’x10’
*** number of pixels available for the background analysis = total number of pixels – (confusion factor) x (number of galaxies)
= 1.7x10^5 – (3pics x 3pics) x (number of galaxies)
2. Spectroscopy
Spectroscopy
Spectral
resolution l/l
Survey area
Exposure time
Detection limit (5s)
[nW/cm2/sr]
Number of
galaxies
Number of
dark pixels
30
(l = 2.0 – 5 mm)
3” x 73”
x 100 directions
(various b and b)
1 pointing (500 s)
x 100 directions
30 (pixel binning)
~10 (10 sky average)
2
90
Fluctuation of the sky-4
Detection of fluctuation with 2MASS data
Kashlinsky et al. ApJ 279, L53 (2002), Odenwald et al. ApJ 283, 535 (2003)
Interpretation of the 2MASS fluctuation with pop.III stars
Theoretical estimation of fluctuation I.
Magliocchetti, Salvaterra and Ferrara MN, 342, L25 (2003)
Sharp drop at ~200 arcsec
8.6 Mpc at zend=8.8
Fluctuation is dominant at the J band