Post on 23-Feb-2016
description
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