Space Infrared Astronomy in Japan

2009 UN BSS & IHY Workshop, September 22, 2009

MATSUMOTO, Toshio

Seoul National University, ISAS/JAXA

Infrared observation is inevitable to understand the evolution of the Universe

IRAS 12, 60, & 100 µm (NASA/IPAC)

Most of energy is emitted in infrared Wavelength (1mm – 1mm)

Far infrared view of ORIONThermal emission of interstellar dust is Indication of star forming activity

Optical image

Why space infrared observation?●Wide wavelength coverage

Atmosphere is opaque in infrared regionSome windows at near and mid IRFIR observation can be done only from space

●Very low backgroundHigh sensitivityAbsolute observation of diffuse extended sources

But telescope must be cooled down!

Thermal emission and transparency of the atmosphere

1.0

0.0

10-3

10-6

10-9

Surfa

ce b

right

ness

(W.m

-2.m

m-1

.sr-1

)

Tra

nspa

renc

y

1 10 100 1000

Wavelength (mm)

220k Blackbody

4 km

14 km

40 km

250 kmZodiacal light

IPD emission

ISD emission

CMB

Cooled telescope is necessary to utilize low background condition

Space infrared observation is difficult!

• How to keep liquid Helium at zero gravity?Separation of gas from liquid

Porous plug

• How can we realize long life of coolant?Cryostat must survive after the shock and vibration during launch

GFRP tension support

cf UFURU:1970IRAS:1983 COBE, ISO, Spitzer

Many rocket and balloon flights(1970’ – 1980’)

● Short time scale and low cost, but limited capabilityshort observing time (rocket)narrow wavelength coverage, high background (Balloon)

● BenefitsDevelopment of key technology for futureGood training for students

Must be scientifically significant !

19 sounding rocket experiments, 13 balloon flights, 2 satellite launch

Balloon born liquid Nitrogen cooled telescope

Rocket experiment to measure infrared background with liq.He cooled telescope

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

Focal Plane Instrument

NIRS (Near Infrared Spectrometer)wavelength coverage 1.4-4.0 mm spectral resolution 0.13 mmbeam size 8 arcmin. x 8arcmin.

MIRS (Mid infrared spectrometer)wavelength coverage 4.5-11.7mm spectral resolution ~0.3 mmbeam size 8 arcmin. x 8arcmin.

FILM (Far-Infrared Line mapper)wavelength coverage 158(CII) and 63 (OI) mm spectral resolution l/Dl~ 400beam size 8 arcmin. x 13 arcmin.

FIRP (Far-Infrared Photometer)wavelength coverage 150-700 mm spectral resolution l/Dl~ 3beam size 8 arcmin. x 13 arcmin.detector temperature 0.3K

IRTS detected excess emission that could be pop.III origin

Based on the success of IRTS, we proposed dedicated infrared astronomical satellite to ISAS, ASTRO-F (AKARI), on 1995

ASTRO-F●70 cm aperture, 　　 liq.He cooled telescope●Survey mission,

higher sensitivity and better spatial resolution longer wavelength band (200mm)

than IRAS

Advanced space cryogenics

• Effective use of radiative cooling • 2-stage Stirling Cooler

Life time of liquid Helium 550 days with 170 liter Liq. He

cｆ . IRAS and COBE 10 months with 600 liter Liq. He

Satellite system

AKARI, Focal Plane Instrumnets

IRC(Infrared Camera) 512x412 InSb array camera, 1.5”/pixel imaging observation at 2.4, 3.2, and 4.1 mm low resolution spectroscopy256x256 SiAs array, 2.4”/pixel imaging observation at 7~24 mm low resolution spectroscopy

FIS(Far Infrared Surveyor) all sky survey with 4 bands

from 50 – 200 mm Fourier spectroscopy

• ASTRO-F was launched on February 22, 2006, and named as “AKARI”

• Orbit : sun synchronous orbit, 705 km altitude

• Liq. He ran out on August 2007

• Near infrared observation is still being continued (phase 3) owing to cooler

http://www.ir.isas.jaxa.jp/ASTRO-F/Observation/

Far infrared image of reflection nebulae IC4954

Star forming region observed with AKARI

Visible light

AKARI 9 & 18 mmCredit: Davide De Martin (http://www.skyfactory.org/), ESA/ESO/NASA FITS Liberator & Digitized Sky Survey

Reflection nebulae IC1396

Large Megellanic Cloud

Visible light

Far infrared image of LMC observed with AKARI

AKARI65, 90, & 140 µm

AKARI detected fluctuation of sky brightness which could be pop.III origin

2.4mm 3.2 mm 4.1 mm

90% of the whole sky was surveyed

~880,000 sources are detected

AKARI-FIS BSC b-2

PRELIMINARY

WIDE-S (90 µm)

284,633 sources

•First point source catalogue will be opened to public in next spring

Next mission after AKARI?Space observation is very sensitive, but angular resolution is not so good compared with optical and radio due to the diffraction limit.

l/D ~ 30 arcsec, at 100 mm for AKARI

It is too heavy to install large aperture telescope for the traditional space infrared mission (IRAS, ISO, AKARI).

New idea is required!

No cryogen, warm launchCooled down in space with mechanical coolerEffective radiation cooling at L2 orbit

-> SPICASpace Infrared Telescope for Cosmology and Astrophysics

Outline of SPICATo reveal the history of Universethrough Infrared Observations

Telescope: 3.5m, 4.5 K HSO: 3.5m, 80K JWST: ~6m, <50K

Core λ: 5-200 μmMIR imaging, spectroscopyFIR imaging, spectroscopy (SAFARI)NIR, MIR coronagraph (option)NIR camera (FPC, option)

Orbit: Sun-Earth L2 Halo Warm Launch, Cooling in Orbit No Cryogen

SPICA is now pre-project phase Final approval will be on 2010 fall

Launch: ～ 2017

SPICA will be opened to world wide community

• We welcome participation of other countriesfocal plane instrumentsDevelopment of softwareSatellite operationObservation and science

• Open time to general community (~20%) is planned

Contact person: nakagawa@ir.isas.jaxa.jp

AKARI Point Source Catalogue(s)

MIR FIR b-2Wavelength (µm) 9, 18 65, 90, 140,

160Number of sources ~880,000 284,633

Detection limit 50 & 130 mJy 0.5~ 7 ~ 13

JyPhotometric uncertainty 7–15 % 30 ~ 50 %

Spatial resolution ~10 arcsec ~1 arcmin

Position uncertainty 1–3 arcsec 4–5 arcsec

•First point source catalogue will be opened to public in next spring