Observational Prospect of NIREBL

Observational Prospect of NIREBL

ISAS/JAXA

T. MATSUMOTO, S. MATSUURA, and T. WADA

Issues to be observed

• Spectral shape Confirmation of the spectral gap at ~1m real? Other spectral features?

• Fluctuation Spatial correlation over the wide range of angular scale Search for the large scale structure at high redshift

• Absolute measurements Avoid ambiguity of the model ZL

Rocket experimentASTRO-FSPICAOut of zodiacal cloud mission

10

100

0.2 0.4 0.6 0.8 1 3 5

Wavelength ( )m

10-9

10-8

1 2 3 4

Wavelengt (W.m-2 .sr-1 )

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 pixel256x256 SiAs array

FIS(Far Infrared Surveyor)Launch target : August, 2005Orbit : sun synchronous orbit, 750km altitudeMission life: ~1.5 year (liq. He holding time) + 2 years (dedicated to NIR Observations)

ISAS/ESA collaboration: 10% of the pointing observations are opened to ESA scientists

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 obseravation (~10 min.)　 This corresponds to ~30 nW m-2 sr-1 for 1 pixel (5) 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

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 (2~5m) Spectrum without contamination of stars and galaxies can be obtained We welcome participation of theoreticians even in planning stage!

IRC SURVEY STRATEGIESIRC SURVEY STRATEGIES

0.02 1 10100

1000 ?

Area (sq. deg.)

Num

ber o

f Poi

ntin

gs

100

10

1

Depth and Area

Expected fluctuation and detection capability of IRC/ASTRO-F

(Cooray et al., submitted to Ap.J.)

IRC background measurements around NEP

1. Wide-band deep imaging in K, L and M bands

* in unit of surface brightness (I

** 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)

Spectral resolution /

Survey area Exposure time Detection limit (5)

[nW/cm2/sr]

Number of galaxies

Number of dark pixels

Spectroscopy 30

(2.0 – 5 m)

3” x 73”

x 100 directions

(various b and )

1 pointing (500 s)

x 100 directions

30 (pixel binning)

~10 (10 sky average)

2 90

2. Spectroscopy

Spectral resolution

/

Survey area [sq.degree]

Exposure time per frame

[# of pointings]

Single pixel detection limit (5) *

[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

Out of zodiacal cloud mission

Infrared observation without the zodiacal light 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

InstrumentationTelescope 5cm dia. lens systemWavelength range 0.8-2.2mPixel FOV ~10’Detector HgCdTeCooling system radiation coolingWeight 3 kg