「あかり」遠赤外線分光観測の成果 · 銀河系内星形成領域:g3.270-0.101,...
TRANSCRIPT
・「あかり」遠赤外線分光器FIS-FTS
・FIS-FTSによる観測
セレンディピタス分光サーベイ
・FIS-FTSのデータ解析
キャリブレーションと標準ツール
・初期成果
銀河中心 Yasuda et al.
星形成領域 Okada et al.
・今後の解析
LMC(セレンディピタスサーベイ)
・将来の展望
遠赤外線分光サーベイの時代へ ~SPICA/SAFARI~
はなしの概要
「あかり」遠赤外線分光器~撮像型フーリエ分光器~
UIR研で開発したスペース用遠赤外線フーリエ分光器
特徴
・天文観測用冷却遠赤外線フーリエ分光器スペース用としてはCOBE/FIRASに次ぐ2番目の装置
・分光と撮像が同時にできる世界初 (Herschel/SPIREに先んじる)
・空間分解能が高い1分角を切る空間分解能での撮像分光
⇒ 細かな空間構造でのスペクトル観測を効率よく行える
ISO/LWSとの比較Gratingによる分光(比分解能:R=150 – 200)
Fabry-Perots分光器による高分解能モードあり(R=6800 – 9700)シングルピクセル(空間分解能:~80”)
Optics Type : polarized Michelson interferometer (Martin-Puplett type)Mirror Driving Type : leaf springs axis support with voice coil actuatorPosition Sensor : optical scale (resolution: 2 µm in o.p.d. ) /wo zero path detectorSpectral Coverage : 55–200 cm-1 (50–180µm)Maximum o.p.d. (L ) : - 0.9 ~ + 2.8 cmSpectra Resolution (R) : 0.19 cm-1 (Full-res. Mode; L=2.8 cm)
[d = 1/(2L)] 1.2 cm-1 (SED mode, L=0.42 cm)Mirror Scan Speed : ~ 0.08 cm s-1
AKARI FIS-FTS
FIS (without top cover) Mirror Driving Mechanism4
Kawada et al., 2008
FIS DesignMartin-Puplett Interferometer
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12m
m15m
m
LW detector SW detector
SW detector (50 – 110 µm) - direct hybrid type - Ge:Ga + Si RO /w In bump - format: 3 x 20 & 2 x 20
LW detector (110 – 180 µm) - compact stacking type - stressed Ge:Ga + Si RO - format: 3 x 15, 2 x 15
Two positionFilter Wheel
Array Alignment(on the sky)
LW
SW
Neptune Image
Detector System: 2D Photoconductive Detector Arrays (Ge:Ga) with CTIAs (Si)Detector Unit Name: SW LWDetector Type: monolithic Ge:Ga array stressed Ge:Ga arrayArray Format: 3 x 20 3 x 15Pixel Size (pitch): 0.5 (0.55) mm 0.9 (1.0) mmPixel FOV: 26.8 x 26.8 arcsec2 44.2 x 44.2 arcsec2
FWHM (major/minor): 44” / 39” 57” / 53”Spectral Coverage: 85–200 cm-1 55–90 cm-1
Sampling Rate: 85.336Hz 170.672HzPSF (x: array major axis): PSFFTS (x, y) = PSFphot (x-7”, y) + PSFphot (x+7”, y)
6SW: e = 0.8; σ1 = 14”; σ2 = 40”LW: e = 0.65; σ1 = 17”; σ2 = 46”
PSF PHOT x , y= exp x2y2
212 1−exp x2
y2
222
xy
AKARI FIS-FTS
FIS-FTSによる観測
指向観測モードで観測
1回約20分間の観測(含む、約8分間のキャル測定)
2種類の検出器で50 – 180μm同時観測3 x 20 pixels / 3 x 15 pixels の撮像分光
分解能の選択Full-res.: 0.2 cm-1; SED: 1.2 cm-1
観測の種類プライマリーモード
ターゲット提案に基づく観測115点(MP、OT、DT)
パラレルモードIRCとの同時観測(IRC優先モード)
452点(MP-FISS3) (IRC指向観測の約1割)
Observation Sequence
SHUTTER CLOSE SHUTTER OPEN CLOSE
Internal B.B.(37K)(~362s)
FTS MODE SCANNER MODE
FTS modestart
Seq. Restart
observing the sky(719s)
FWrotating
FWrotating
FTS modestop
sequence of one pointing observation
30 minutes
Pointing Observation: - up to 3 times in an orbital period the telescope is held to the specific directions. - duration time of one pointing observation is about 30 minutes - effective observing time is about 12 minutes
~7.5 round scans for full-res. mode, ~30 round scans for SED mode - internal blackbody source (~35K) is measured for about 6 minutes in SED mode
prior to the observation - FIS FTS can operate with the IRC observation: parallel observation mode
observing direction is different from the IRC view 8
Observations (2006/04/19 – 2007/08/25)✔ Total Number of Observations: 597 points (12 minutes each)
➔ PV phase : 30 points➔ Primary obs. : 115 points (MP: 62, OT-ISAS: 7, OT-ESA: 24, DT: 22)➔ Parallel obs. : 452 points (MP-FISS3)-----------------------------------------------------------------------------------------------------------------------------------➔ SED mode : 259 points (PV: 21, Primary / Parallel: 50 / 188)➔ Full res. Mode : 338 points (PV: 9, Primary / Parallel: 65 / 264)
(data for several obs. are lost by downlink troubles)
Observing Area (Galactic coordinate)
concentrated on
the Galactic plane (~ 55%)
& Large Magellanic Cloud (~30%)
┼: Parallel Observations□: Primary ObservationsSED mode / Full-res. mode
LMC
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フーリエ分光器とは
2光束の光路差に対する干渉強度の変化=インターフェログラム
時間軸方向への分散 ⇔ 空間軸方向への分散:グレーティング
インターフェログラムのフーリエ変換 ⇒ スペクトル
キャリブレーション (Murakami et al. 2010)
標準天体:惑星(準惑星)~Uranus, Neptune
ISO/LWSとの比較:連続成分&輝線([CII], [NII], [OIII])
高輝度領域に対して検証
中・低輝度領域への拡張が必要
標準ツールの提供
IDLベースの解析ツールを提供
データ解析
Data Processing & Calibration
- non-linearity correction- differentiation- spike removing
- separate each scan- ZPD determination- opd correction- transient response correction
- apodization- numerical integration
of Fourier transform equation- phase correction
- flat fielding- spectral response correction- absolute flux correction- fringe correction
First Data Reduction
Second Data Reduction
Fourier Transform
Corrections
Raw Data
Sky Spectra
Interferograms
Raw Spectra
Calibration:
- laboratory characterizationinternal/external sources
- in flight correction- well-known
astronomical sources- internal blackbody source
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Murakami et al., 2010
Data Processing (1)
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First Data Reduction:
⇐ non-linear correction
⇐ differentiation& spike removing
Second Data Reduction:
⇐ ZPD determination& o.p.d. correction
Fourier Transform:
⇐ raw spectra& phase correction
Data: SED mode
LW07 SW32
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Data Processing (2)Flat Correction
SW(0.6~1.5)
LW(0.2~7)
Spectral Response Correction
LW01 LW19 LW31 SW (all)
(from measurement of aperture lid)
Fringe Correction (by model template method)
LW array has much wider variety of responsivity
SW LW
Wavenumber [cm-1]60 60 60 90909090 130
LW array has wider variety of spectral response
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Calibration- planets as the absolute calibrator,
which have well defined spectral model- comparing with the ISO/LWS observations
for lines and integrated power
⇒ both ISO/LWS and AKARI/FTS calibration is consistent for brighter sources, at least
Lines
Integrated Power
Murakami et al., 2009
FIS-FTSによる初期成果
高い空間分解能と効率のよいマッピング能力
銀河中心領域:Quintuplet and Arches clusetesAKARI Far-Infrared Spectroscopic Observations of the Galactic Center
RegionYasuda et al. (2009)遠赤外線の禁制線([OIII], [NII], [CII])を用いて、クラスター近傍の物理構造を
明らかにした
銀河系内星形成領域:G3.270-0.101, G333.6-0.2, NGC3603, M17Properties of active galactic star-forming regions probed by imaging
spectroscopy with the Fourier transform spectrometer (FTS) onboard AKARIOkada et al., (2010)遠赤外線輝線マップを用いて、星間物質の構造と隠れた励起星を明かにする
近傍銀河のスペクトルマッピングTakahashi et la.
ηカリーナ領域のスペクトルマッピングMatsuo et al.
Scientific Results of AKARI/FTS (1)Line & Continuum Maps
of the Galactic Center RegionYasuda et al. (2009)
[OIII] 88.4µm [NII]122.0µm [CII] 157.7µm
88µm 122µm
(MSX 12µm) (20cm radio continuum)
5 pointing obs.
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Scientific Results of AKARI/FTS (2)
G333.6-0.2
Line mapping of the Galactic HII regions
Full-range Spectrum of the AKARI/FTS
[OIII] 88µm [NII] 122µm [CII] 158µm
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Okada et al. (2010)
9um
18um
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G3.270-0.101
NGC3603
M17
contour: IRC 18µm / MSX 21µm
[CII]158µm [CII]158µm [CII]158µm
[OII]88µm[OII]88µm[OII]88µm
12min 30min 11min
LS-LMC:IRCによるLMCの多バンド広域サーベイの裏観測
2期にわたり188点の観測
前半:SEDモード(30 Dor 近傍)
後半:Full-res.モード(それ以外)
無バイアスな広域スペクトルサーベイ
複数の禁制線([OIII], [CII])を検出
星形成領域、星間物質の空間構造を明かにする
LMC領域の観測
3 de
g
AKARI 90µm map
6 de
g
IRAS 100µm map
AKARI/FTS Observations of the LMC region
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Full-res. modeSED mode
[CII]158µm[CII]158µm [OIII]88µm
188 observing points~50 pixels for each points
遠赤外線分光サーベイの時代へ
将来への展望
Herschel Space Observatory (3.5m telescope)- PACS (Photodetector Array Camera and Spectrometer)
Integral Field Spectrometer: 55-105 & 105-210um (47”x47”:5x5 pixels)
- SPIRE (Spectral and Photometric Imaging Receiver)
Imaging Fourier Transform Spectrometer: 194-672um (2.6' FOV: 37/19 pixels)
- HIFI (Heterodyne Instrument for the Far Infrared Instrument)
157-625um (7bands/12-47”beam) R < 107
SPICA (Space Infrared telescope for Cosmology and Astrophysics)
-SAFARI (SPICA Far Infrared Instrument)
Imageing Fourier Transform Spectrometer: 34-210um (2'x2' FOV)