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High Energy Astrophysics in Japan
Makishima Kazuo (Univ. Tokyo / RIKEN)牧島 一夫 ( 東京大学 / 理化学研究所 )
島 = tou, shima ; 漢音 , 日本音
汽車 自動車火車 汽車
Prof. Oda’s group (1975)
R.Giacconi (Nobel Prize 2002 )
Minoru Oda 小田稔 (1923 〜 2001)
In 1962, a sounding rocket detected strong X-rays from some celestial object, which later turned out to be the brightest cosmic X-ray source, Scorpius X-1.
宇宙科学研究所 (ISAS) 東京大学理学部 (U. Tokyo)助手 (R.Associate) 助教授 Assoc. Prof.) 教授 (Prof.)
宇宙 X 線 Cosmic X-rays
太陽 X 線 Solar X-rays
YohkoHXT
ASTRO-E HXD
ASRO-ELaunchfailuire
GingaLAC
Hakucho
ASCAGIS
SPC batteryTenm
a
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
20
02
RIKEN
ASTRO-E2 HXD
SXT
Data recorderHinotori
battery
My Participation to Satellite Projects
Prologue: Ohsumi 大隅On 1970 February 11, the Institute of Space and Astro-nautical Science (ISAS ;宇宙科学研究所 ) successfully launched the first Japanese artificial satellite, Ohsumi. This was achieved after 4 launch failures.
重量 Weight : 24 kg軌道 Orbit : 近地点 Perigee 350 km 遠地点 Apogee 5140 km 軌道傾斜角 Inclinaton 31deg
科学衛星(宇宙科学研究所)
L- 4 S M-4S M-3C M-3H M-3S M-3SI I M-5
淡青 ,新星 ,電波
Ohsumi
淡青2 ,太陽 , CORSA,
白鳥淡青3 ,極光 ,磁気圏
淡青4 ,火鳥 , 天馬 ,
大空
Sakigake,彗星 , 銀河 ,
曙 , 飛天 ,陽光 , ASCA
HALCA,Nozomi,ASTRO-E,Hayabusa
1970’s
Former 80’s Latter
80’s 〜Former 90’s
Geophysics
Solar
Physics
Astrophysics
Planetary
衛星
3段
2段
1 段
How a 3-Stage Rocket Works
1 段 3段Kick motor(optional)2段
1. Hakucho 白鳥
重量 Weight : 96 kg軌道 Orbit : 近地点 Perigee 545 km 遠地点 Apogee 577 km 傾斜角 Inclination 30 deg[E] Elementary process 素過程
[A] Astrophysics 天体物理[I] Instrumentation 観測装置[S] Spacecraft Technology 衛星技術
The first Japanese cosmic X-ray satellite, launched on 1979 February 21. Re-entered atmosphere on 1985 April 16. This was a recovery mission to the CORSA satellite, which had been lost in 1976 due to a rocket failure.
[S] Attidue ( 姿勢 ) of Hakucho
Mx
Mz
My
Attitude of Hakucho was stabilized by a free spin with a period of 〜 10 sec.
Attitude maneouvering was done by activating 3 electric magnets, and utilizing the magnetic torque between the geomagnetic field.
Detectors mounted on the top face performed pointing observations, while those on the sides scanned over the sky.
Loca
l mag
.field
High Voltage
Simple, cheap, large-areaSuited to 2 〜 20 keVΔE/E 〜 15% @ 6 keVPulse Height ∝ E ×Vα (α 〜 6)
A photoelectron
Electron multiplication
Charge cloud
An X-ray
Thin wire anode
Collimator and Window support
Pre-amplifier
Very thin Metal window
Main Electronics
HermeticInsulator Gas outletGas inlet
Ar+CH4(10%)
[I] Proportional Counters ( 比例計数管 )
Metal box or tube
pulse
[E] Blackbody Radiation ( 黒体放射 )
◆ Photon number spectra
0.1 1 10
E (keV)
100
10
1
0.1
0.01
phot
ons/
sec/
keV
f ∝E×kT Peak at
E 〜 2 kT
kT = 1 keV
kT = 3 keV
kT =0. 3 keV
fph=A E2/{1-exp(E/kT)}
Total emitted luminosity L = 4πR2σT4
Theory predicts that a neutron star has a radius of R 〜 10 km, and its luminosity saturates at the Eddington limit of 2×1038 erg/s. We then expect T = 2.0 keV.
If T and L are measured, we can estimate R from observation.
◆ Planck’s formula
◆ Stefan-Boltzmann’s law
Flux
R
15 sec
Blackbody kT
[A] Scientific Highlights from HakuchoUsing rotation modulation collimators, w observed many X-ray b
ursts (thermo-nuclear flash on the NS surface).Confirmed R 〜 10 km (Ohashi et al. ApJ 254, 254, 1982). Assuming burst luminosity = Eddington limit, the Galactic Cente
r distance should be 〜 7 kpc rather than 10 kpc (Inoue et al. ApJ 250, L71,1981).
2.0 keV
10 km
2. Hinotori 火の鳥The first Japanese solar X-ray satellite, lunched in 1981 Fe
bruary, aiming at a solar maximum.Using rotating modulation collimators coupled to NaI scintil
lation counters, it successfully resolved hard X-ray images of solar flares witn ~30” resolution.
Mission ended in 2 years due to a trouble in the data recorder.
重量 Weight : 188 kg軌道 Orbit : 近地点 Perigee 576 km 遠地点 Apogee 644 km 傾斜角 Inclination 31 deg
[I] How a Scintillation Counter Works
Simple, cheapSuited to 20 〜 600 keVΔE/E 〜 20% @ 100 keVPulse Height ∝ E ×Vα (α 〜 7)
High Voltage
Bleeder
Main Electronics
An X-ray
Pre-amplifier
Magnetic shield
Photo-Multipliertube
Light guide
NaI crystal
Visible-light shield
Scintillation
pulse
[A] Scientific Highlights from HinotoriA gradual rim flare of 1981 April 27
(Takakura et al. ApJ 270, L83, 1983)
17-40 keV hard X-ray image at the flare peak40-67 keV
17-40 keV
67-150 keV
150-350 keV
2 arcmin
10 min
Hard X-ray emission from loop footpoints, and also from loop top?
Solar
disk
[E] Non Thermal Bremsstrahlung ( 非熱的制動放射 )
Relativistic
electrons
Collision with ions
Collision with e-
0.1 1 10E (MeV)
0.1 1 10E (MeV)
Softer e’s are subject to larger Coulomb loess
For a mono-energetic electron dsitribution
photon flux ∝ 1/E
Coulomb scatt. --- elastic, but large momentum transfer
Bremsstrahlung -- hard X-rays Coulomb scatt. --- inelastic, als
o momentum changes Negligible Bremsstrahlung
Convolved with power-law electron distribution
[E] Optically-Thin Thermal Plasma Emission
Optically-thin hot plasmas (e.g., solar corona) become strong X-ray sources. Then, how does their emission differ from the blackbody (optically thick emission) ?
L = n2V Λ(T,Z) ∝ volume ( 体積 ), rather than surface area ( 表面積 ), bacause the source is transparent.
Continuum stronger at lower energies, due to the absence of self-absorption:
fph=A E-1.4exp(-E/kT)
Accompanied by strong atomic emission lines. 0.1 1 1
0E (keV)
100
10
1
0.1
0.01
phot
ons/
sec/
keV
both kT = 1 keV
Thin-thermal
Blackbody
[S] Orbit ( 軌道 ) of HinotoriNear-Earth X-ray satellites must have altitudes between 500 〜 600 km.If < 500 km ⇒ Air drag shortens the satellite lifetime.If > 600 km ⇒ Particle background increases due to the
radiation beltIn such an orbit, a satellite makes 15 revolutions per day (period of 〜 95 min).
From a tracking station in Japan, we can have only 5 “contacts” per day, each 〜 10 minutes.
Utilizing these 50 minutes, all commands must be sent to the satellite, and all data stored onboard must be received.
1
35
913
After operating for 〜 2 years, Hinotori lost proper functioning of its data recorder (a tape reccordder).
3. Tenma 天馬The 2nd Japanese cosmic X-ray satellite, launched on
1983 February 20. It operated over the same era as the European EXOSAT.
It carried onboard the Gas Scintillation Proportional Counter (SPC) with a factor 2 better energy resolution than conventional proportional counters.
It has initiated a number of important spectroscopic studies, including the Fe-K diagnostics, although targets were mostly limited to Galactic objects.
Mission ended in 1.5 years due to a battery explosion.
重量 Weight : 216 kg 軌道 Orbit : 近地点 Perigee 497 km 遠地点 Apogee 503 km 傾斜角 Incl. 32deg
Tanaka et al. PASJ36, 641 (1984)
[I] How to Improve the Energy Resolution?
Accelerated in a parallel E-field, each electron emits many UV photons
Amplified by photo-multiplier
Accelerated in a cylindrical E-field, e‘s are multiplied sequentially
Additionalfluctuation
◆ProportionalCounter
◆Gas Scintil-lation P.C.
( Tenma SPC, ASCA GIS)
◆Solid State Detector
No signal amplification
Numerous e-h pairs
Low-noise amplifierElectrical
noise
X-ray
Primary e’s with fluct
uation
Littlefluctuation
[A] Scientific Highlights from Tenma (1)
Koyama et al. ApJ 38, 121 (1986)
Tsunemi et al. ApJ 306, 248 (1986)
From various cosmic hot plasmas, Tenma detected ionized (mainly He-like) Fe-K lines at 〜 6.7 keV. These lines confirmed thermal process in these objects; provided information on the plasma temperature and Fe abundance; and allowed us to examine the plasma for ionization (non-) equilibrium.
Okumura et al. PASJ 40, 639 (1988)
銀河団Perseus clusterFe/H 〜0.3 solar
銀河面X線放射Galactic ridgeX-ray emissionHot plasmas fill the interstellar space!
超新星残骸 Cas AIonization non-equilibrium convirmed!
[A] Scientific Highlights from Tenma (2)
Fluorescent K-lines of neutral Fe was also detected at 6.4 keV from various objects. The lines provide a valuable diagnostic tool of cold matter distribution around the X-ray sources.
Nagase et al. PASJ 38, 547 (1986)
The binary X-ray pulsar (a mass accreting magnetic NS), Vela X-1
Matusoka et al. PASJ 38, 285 (1986)
The Seyfert galaxy NGC4151
out of eclipse near eclipse
instrumental
[A] Scientific Highlights from Tenma (3) Mitsuda et al. (PASJ 36, 741, 1984) successfully decomposed spectra o
f low-mass NS binaries into emission from a standard accretion disk (diskBB model), and a blackbody from the NS surface.
The same MCD model can successfully describe high-state spectra of the BH candidate GX339-4. The disk inner radius is constant, at 〜 3 Rs (Makishima et al. ApJ 308, 635,1986) .
diskBB model
1 week
30
20
10
0
Disk inner radius (km)diskBB
blackbody
[S] Electric Power of a Satellite
Solar cells太陽電池
shunt
Spacecraft and instruments
◆ Satellite Day 昼 ( 〜 60min)
◆ Satellite Night 夜 ( 〜 30min)
NiCd battery 2次電池
time
Bat V電圧
shunt
Spacecraft and instruments
NiCd battery 2次電池
death!!!~1.2V/cell
~1. 6V/cell!!!
(charge) (discharge)
4. Ginga 銀河The 3rd cosmic X-ray satellite of Japan, launched on 1987 February
5 and re-entered on1991 Novemer 1. It carried onboard the Large Area Proportional Counter (LAC), develop
ed under an extensive UK-Japan collaboration. It had an improved spacecraft performance, e.g., 3-axis stabilization,
CPU-based attitude control, etc. It opened a full window in the 2-30 keV range to extra-galactic X-ray
sources, including SN1987A.
重量 Weight : 420 kg近地点 Perigee: 530 km遠地点 Apogee: 670 km
Turner et al. PASJ 41, 345(1989)
[I] Background Reduction using MWPC
◆ MPWC = Multi-Wire Proportional Counter ( 多芯比例計数管)HEAO-1 A2, EXOSAT ME, Ginga LAC, RXTE PCA
R1 L1
V2
V1S23
A schematic cross section of the Ginga LAC detector(Turner et al. Publ. Asttr. Soc. Japan 41, 345, 1989)
[S] Three-Axis Stabilization (3 軸制御 )
A
BC
D
x
y
z
A 〜 D all spin up ⇒ satellite rotates around Z-axis
Angular momentum is carried by four fast-spinning bias momentum wheels, while the satellite body is at rest.
Three wheels are sufficient, but the 4th one is installed for redundancy.
A&B spin up, C&D spin down ⇒ around x-axis
A&D spin up, B&C spin down ⇒ around y-axis
• The highly sensitive Ginga detected X-rays from neaby normal galaxies.
• The emission from M31 (Andromeda) is dominated by LMXBs (Makishima et al. PASJ 41, 697, 1989).
[A] Scientific Highlights from Ginga (1)
TheM31 spectrum 〜 that o a Galactic LMXB, 4U1820-30.
The diskBB+BB model can explain the M31 spectrum above 〜 2 keV.
[E] Photoelectric Absorption of X-rays
10-22
10-20
σ[cm-2/H]
10-24 0.1 1 10
E (keV)
10
1
0.1
Wilms, Allen and McCray ; ApJ 542, 914-924 (2000)
◆Interstellar photoelectric absorption cross sectoin ◆ Absorbed spectra
NH <1020
σ∝ E -2.5
CO
Ne
Mg
Si
S
Fe1023
1024
NH=1022
NH=1021
Highly absorbed spectra have been detected from a number of Type II Seyfert galaxies (e.g., Awaki et al. PASJ 43, 195, 1991).
Type II objects show systematically stronger Fe-K lines than Type I’s.
These results support the “unified scheme” of AGNs; Type I are viewed pole-on, while Type II edge-on.
[A] Scientific Highlights from Ginga (2)
NGC4570(Type II)
NGC4593(Type I)
1 2 5 10 20 50
Energy (keV)
◆ A tansient pulsar X0331+53 Makishima et al. ApJ 365, L59 (1990)
Er = 28 keV →
B = 2.4×1012 G
0
2
4
6
8
10
Cyclotron Res. Energy (keV)
Nu
mb
er
10 100202 5 50
Log[B/(1+z)] (Gauss)12 13
Ginga detected elecctron cyclotron absorption lines from a dozen binary X-ray pulsars (Makishima et al. ApJ 525, 978,1999).
The measured surface magnetic fields are tightly clustered over (1-4)×1012 G, arugueing against the magnetic field decay hypothess.
[A] Scientific Highlights from Ginga (3)
SAXGinga RXTE
ASTRO-E2 HXD
ASCA
After Hinotori, the second Japanese solar observatory Yohkoh was launched on 1991 August 30.
It kept observing the sun for a full solar cycle . In december 2001, however, Yohkoh received an attitude distu
rbance during a solar eclipse, and the NiCd battery became empty. This caused the mission termination.
5. Yohkoh 陽光
重さ Weight : 395 kg近地点 Perigee : 〜 500 km遠地点 Apogee : 〜 800 km
Ogawara et al. PASJ 44, L41 (1992)
Tow imagers: Soft X-ray Telescope: Using a high-resolution mirror and the first
space-use X-ray CCD, it took millions of coronal pictures, and innovated the solar physics.
Hard X-ray Telescope: Employing modulation collimators in “Fourier-synthesis” configuration, it succeeded in the high-resolution (~5”) imaging of more than 1000 solar flares in the 15-95 keV hard X-rays. Particle acceleration is being studied.
Two spectrometers: The Bragg Crystal Spectrometer: High energy-resolution diagnosti
cs of detailed plasma motion. The Wide Band Spectrometer: from 〜 1 keV to ~30 MeV.
[I] Instruments onboard Yohkoh
[E,I] How to Reflect and Focus X-rays ?
Visible light 可視光 X-ray
◆Total reflection 全反射
n < 1
refractive index (屈折率 ) n > 1
Parabolloid 回転放物面
Optical axis
光軸
Focal plane 焦点面
◆Paraboloid collector
Paraboloid 回転放物面
Hyperboloid 回転双曲面
◆Wolter Type I Optics
ActuatorsMagnetic torquersMomentum wheelsGas jets…
[S] Closed-loop Attitude Control ( 姿勢制御)
Attitude Sensors Star tarckers Sun sensors Horizon sensors Gyroscopes…
Dynamical response of the
satellite
比較
Target attitude
Automated Attitude Calclation
Error signal
宇宙科学研 http://www.isas.ac.jp
Long-term variation of the coronal activity
Solar flares are powered by magnetic reconnection!
Solar corona is probably heated by reconnection through numerous micro-flares .
However, the basic puzzle still remains: why there should be a 5 million K corona above the 6000 K photosphere?
[A] Highlights of the Soft X-ray Telescope
X-ray colona
[A] Highlights of the Hard X-ray Telescope
36
100
1000
200
0
0
0
0
0
0
40
80
2000
6000
600
600
1 minutes
53-93 keV
6.2-8.8 MeV
0.22-1.4 MeV
10-30 MeV
1998 August 18, UT 22h 16m
15-23 keV33-53 keV
14-23 keV
33-53 keV
Sola
r rim
30arcsecThe largest g
amma-ray flare ever detected with Yohkoh
Evidence of gamma-ray emission from loop-top regions
Particles are accelerated at the loop top?
[A] A Possible Scenario of Acceleration
Magnetic field line
Main acceleratin regoin
Reconnection point
photosphere
Hardest, impulsive gamma-raysSofter, gradual gamma-rays
Hard X-rays
Cool plasma stream
Accelerated electrons
6.ASCA 飛鳥 Advanced Satellite for Cosmology and Astrophysics
重量 Weight : 417 kg近地点 Perigee: 520 km遠地点 Apogee: 620 km
Developed under a Japan-US collaboration, and launched on 1993 February 20 (10 years since Tenma). It carried high-throughput mirrors working up to 10 keV, coupled to the SIS (CCD camera) and the Japanese GIS (imaging GSPC).
ASCA produced a revolution in the cosmic X-ray study. ASCA lost the attitude stability on 2001 July 14 due to a big solar
flare, and re-entered on 2001 March 2.
Tanaka et al., PASJ 46, L37(1994)
[S] Radiative Cooling of Instruments
Instruments such as CCDs may be cooled to 〜 100 ℃ by using thermoelectric cooler (TEC), heat pipe, and radiator panels.
CCD
TEC
Heat sink
Heat pipe
sunshade
Radaitor panel
Plastic (high far-IR emissivity)
Silver or Alminium (low near-IR absorptivity)
[I] What are required for X-ray CCDs?
In the flux-accumulation mode (e.g. Yohkoh SXT)The front protective layer as thin as possible, to incre
ase the soft X-ray transmission. The depletion layer as thick as possible, to increase t
he hard X-ray stopping power.
In the single-photon detection mode (e.g. ASCA SIS, Chandra ACIS, XMM-Newton EPIC), in additon
A very high charge-transfer efficiency, to ensure a good energy resolution (ΔE/E 〜 2%@ 6 keV).
Low-noise readout electronics to retain good energy resolution
A fast clocking to avoid photon pile-up.
[E] Dual Scientific Merits of ASCA(1)Superior energy
resolution (with particularly the SIS)
(2) Hard X-ray imaging in energies above 〜 2 keV (particularly non-thermal emission with the GIS)
Dual Doppler-shifted atomic lines from SS433 (Kotani et al. PASJ 46, L147, 1994 )
Gyration around magnetic fields
Collision with soft photons, particularly of the CMB
Relativistic electrons with Lorentz factor γ
Synchrotron radiation at ν 〜 106B[μG]γ2 Hz
Inverse Compton emission at ν 〜 νsoftγ2
[A] Individual Talks from Japan
Non-thermal X-rays Makoto Tashiro (田代 信) [Sept. 21, 16:50]Thermal X-rays from clusters of galaxies
Isao Takahashi (高橋 勲) [Sept.22, 9:15]Diffuse emission from spiral galaxies
Hiromitsu Takahashi (高橋弘充) [Sept.22,14:40]Black hole binaries and ULXs
Aya Kubota (久保田あや) [Sept.22,17:25]AGNs, particularly those of low luminosities
Yuichi Tearshima (寺島雄一) [Sept.22,18:15]Gamma-ray bursts
Toru Tamagwa (玉川 徹) [Sept.24, 8:30]
On 2000 February 10, we failed to put the 5th X-ray satellite ASTRO-E in orbit, due to a rocket trouble. The Hard X-ray Detector (HXD), aiming at the highest sensitivity in the 10-600 keV range, was also lost.
However, we have been given another chance, and will launch ASTRO-E2 in January 2005.
We are busy integrating the HXD-II.
Epilogue