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

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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