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High Energy Astrophysics in Japan

High Energy Astrophysics in Japan. 島 = tou , shima ; 漢音 , 日本音. Makishima Kazuo (Univ. Tokyo / RIKEN) 牧島 一夫 ( 東京大学 / 理化学研究所 ). 火車 汽車. 汽車 自動車.

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High Energy Astrophysics in Japan

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  1. High Energy Astrophysics in Japan 島= tou, shima ; 漢音, 日本音 Makishima Kazuo (Univ. Tokyo / RIKEN) 牧島 一夫 (東京大学 / 理化学研究所) 火車汽車 汽車自動車

  2. 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. R.Giacconi (Nobel Prize 2002 ） Minoru Oda 小田稔 (1923〜2001) Prof. Oda’s group (1975)

  3. 1980 1986 2002 1984 1990 1982 1992 1994 1996 1998 1988 2000 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.) battery SPC Tenma ASCA GIS Ginga LAC SXT Yohko HXT Data recorder Hinotori My Participation to Satellite Projects RIKEN ASTRO-E2 HXD Hakucho ASTRO-E HXD ASRO-E Launch failuire 宇宙X線 Cosmic X-rays 太陽X線 Solar X-rays battery

  4. 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

  5. Latter 80’s〜 Former 90’s Former 80’s 1970’s 科学衛星（宇宙科学研究所） Sakigake, 彗星, 銀河, 曙, 飛天, 陽光, ASCA HALCA, Nozomi, ASTRO-E, Hayabusa 淡青４, 火鳥, 天馬, 大空 淡青２, 太陽, CORSA, 白鳥 淡青３, 極光, 磁気圏 淡青, 新星, 電波 Geophysics Solar Physics Astrophysics Planetary Ohsumi L-４S M-4S M-3C M-3H M-3S M-3SI I M-5

  6. 1段 ２段 ３段 Kick motor (optional) How a 3-Stage Rocket Works 衛星 ３段 ２段 1段

  7. 1. Hakucho白鳥 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. 重量 Weight： 96 kg 軌道 Orbit： 　近地点 Perigee545 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

  8. Mz Mx My [S] Attidue (姿勢) of Hakucho • 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. Local mag.field

  9. An X-ray pulse Charge cloud A photoelectron Electron multiplication [I] Proportional Counters (比例計数管) Very thin Metal window Collimator and Window support High Voltage Thin wire anode Pre-amplifier Ar+CH4(10%) Metal box or tube Hermetic Insulator Gas inlet Gas outlet Main Electronics • Simple, cheap, large-area • Suited to 2〜20 keV • ΔE/E 〜 15% @ 6 keV • Pulse Height ∝ E ×Vα (α 〜6)

  10. kT = 3 keV kT = 1 keV f ∝E×kT Peak at E 〜2 kT kT =0. 3 keV [E] Blackbody Radiation (黒体放射) • Planck’s formula • Photon number spectra fph=A E2/{1-exp(E/kT)} 100 10 1 0.1 0.01 • Stefan-Boltzmann’s law • Total emitted luminosityL = 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 andL are measured, we can estimate R from observation. photons/sec/keV 0.1 1 10 E (keV)

  11. Flux 15 sec Blackbody kT 2.0 keV R 10 km [A] Scientific Highlights from Hakucho • Using rotation modulation collimators, w observed many X-ray bursts (thermo-nuclear flash on the NS surface). • Confirmed R 〜10 km (Ohashi et al.ApJ254, 254, 1982). • Assuming burst luminosity = Eddington limit, the Galactic Center distance should be 〜 7 kpc rather than 10 kpc (Inoue et al. ApJ250, L71,1981).

  12. 2. Hinotori火の鳥 • The first Japanese solar X-ray satellite, lunched in 1981 February, aiming at a solar maximum. • Using rotating modulation collimators coupled to NaI scintillation 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 Perigee576 km 　遠地点 Apogee 644 km 　傾斜角 Inclination 31 deg

  13. Scintillation pulse An X-ray [I] How a Scintillation Counter Works High Voltage Magnetic shield Bleeder Photo- Multiplier tube Light guide Pre-amplifier NaI crystal Visible-light shield • Simple, cheap • Suited to 20〜600 keV • ΔE/E 〜 20% @ 100 keV • Pulse Height ∝ E ×Vα (α 〜7) Main Electronics

  14. 17-40 keV 40-67 keV 67-150 keV 150-350 keV [A] Scientific Highlights from Hinotori 10 min A gradual rim flare of 1981 April 27 (Takakura et al.ApJ270, L83, 1983) 17-40 keV hard X-ray image at the flare peak Solar disk 2 arcmin Hard X-ray emission from loop footpoints, and also from loop top?

  15. Coulomb scatt. --- elastic, but large momentum transfer • Bremsstrahlung -- hard X-rays • Coulomb scatt. --- inelastic, also momentum changes • Negligible Bremsstrahlung 0.1 1 10 E (MeV) 0.1 1 10 E (MeV) [E] Non Thermal Bremsstrahlung (非熱的制動放射) Collision with ions Relativistic electrons Collision with e- • For a mono-energetic electron dsitribution • Convolved with power-law electron distribution photon flux ∝ 1/E • Softer e’s are subject to larger Coulomb loess

  16. Thin-thermal Blackbody [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) ? 100 10 1 0.1 0.01 • L = n2VΛ(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. photons/sec/keV 0.1 1 10 E (keV) both kT = 1 keV

  17. 13 1 3 9 5 [S] Orbit (軌道) of Hinotori • Near-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 belt In 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. After operating for 〜2 years, Hinotori lost proper functioning of its data recorder (a tape reccordder).

  18. 重量：216 kg 軌道： 　近地点　497 km 　遠地点　503 km 軌道傾斜角 32 deg 3. Tenma天馬 Tanaka et al. PASJ 36, 641 (1984) • 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 Perigee497 km 　遠地点 Apogee503 km 　傾斜角 Incl.32deg

  19. X-ray Low-noise amplifier No signal amplification • Solid State Detector Electrical noise Numerous e-h pairs [I] How to Improve the Energy Resolution? • Proportional • Counter Additional fluctuation Accelerated in a cylindrical E-field, e‘s are multiplied sequentially Primary e’s with fluctuation Accelerated in a parallel E-field, each electron emits many UV photons Amplified by photo-multiplier • Gas Scintil-lation P.C.（Tenma SPC, ASCA GIS) Little fluctuation

  20. 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. [A] Scientific Highlights from Tenma (1) 銀河面Ｘ線放射 Galactic ridge X-ray emission Hot plasmas fill the interstellar space! 銀河団 Perseus cluster Fe/H 〜 0.3 solar 超新星残骸 Cas A Ionization non-equilibrium convirmed! Tsunemi et al.ApJ306, 248 (1986) Okumura et al.PASJ 40, 639 (1988) Koyama et al. ApJ 38, 121 (1986)

  21. instrumental out of eclipse near eclipse [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. The Seyfert galaxy NGC4151 The binary X-ray pulsar (a mass accreting magnetic NS), Vela X-1 Nagase et al. PASJ38, 547 (1986) Matusoka et al. PASJ38, 285 (1986)

  22. Disk inner radius (km) 30 20 10 0 diskBB 1 week [A] Scientific Highlights from Tenma (3) • Mitsuda et al. (PASJ 36, 741, 1984) successfully decomposed spectra of 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 blackbody

  23. !!! death!!! [S] Electric Power of a Satellite • Satellite Day 昼 (〜60min) • Satellite Night 夜 (〜30min) Solar cells 太陽電池 NiCd battery ２次電池 NiCd battery ２次電池 shunt shunt Spacecraft and instruments Spacecraft and instruments (discharge) (charge) ~1. 6V/cell Bat V 電圧 ~1.2V/cell time

  24. 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), developed 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. PASJ41, 345(1989)

  25. [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 A schematic cross section of the Ginga LAC detector (Turner et al. Publ. Asttr. Soc. Japan41, 345, 1989) R1 L1 V2 S23 V1

  26. [S] Three-Axis Stabilization (3軸制御) Angular momentum is carried by four fast-spinning bias momentum wheels, while the satellite body is at rest. z B • A〜D all spin up ⇒ satellite rotates around Z-axis C y • A&B spin up, C&D spin down ⇒ around x-axis A D • A&D spin up, B&C spin down ⇒ around y-axis x Three wheels are sufficient, but the 4th one is installed for redundancy.

  27. The diskBB+BB model can explain the M31 spectrum above 〜2 keV. TheM31 spectrum 〜that o a Galactic LMXB, 4U1820-30. [A] Scientific Highlights from Ginga (1) • The highly sensitive Ginga detected X-rays from neaby normal galaxies. • The emission from M31 (Andromeda) is dominated by LMXBs (Makishima et al. PASJ41, 697, 1989).

  28. σ∝ E-2.5 NH=1021 Ne Si NH=1022 1023 C Fe O 1024 Mg S [E] Photoelectric Absorption of X-rays • Interstellar photoelectric absorption cross sectoin • Absorbed spectra σ[cm-2/H] NH＜1020 10 1 0.1 10-20 10-22 10-24 0.1 1 10 E (keV) Wilms, Allen and McCray ; ApJ542, 914-924 (2000)

  29. [A] Scientific Highlights from Ginga (2) • Highly absorbed spectra have been detected from a number of Type II Seyfert galaxies (e.g., Awaki et al. PASJ43, 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. NGC4593 (Type I) NGC4570 (Type II)

  30. Log[B/(1+z)] (Gauss) 10 SAX Ginga RXTE 8 12 13 ASTRO-E2 HXD ASCA 6 Number 4 2 0 2 20 10 100 5 50 Cyclotron Res. Energy (keV) [A] Scientific Highlights from Ginga (3) • Ginga detected elecctron cyclotron absorption lines from a dozen binary X-ray pulsars (Makishima et al. ApJ525, 978,1999). • The measured surface magnetic fields are tightly clustered over (1-4)×1012G, arugueing against the magnetic field decay hypothess. • A tansient pulsar X0331+53 Makishima et al.ApJ365, L59 (1990) Er = 28 keV → B = 2.4×1012G 2 5 10 20 50 Energy (keV)

  31. 5. Yohkoh 陽光 • 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 disturbance during a solar eclipse, and the NiCd battery became empty. This caused the mission termination. Ogawara et al. PASJ44, L41 (1992) 重さ Weight： 395 kg 近地点 Perigee : 〜500 km 遠地点 Apogee : 〜800 km

  32. [I] Instruments onboard Yohkoh • 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 diagnostics of detailed plasma motion. • The Wide Band Spectrometer: from 〜1 keV to ~30 MeV.

  33. [E,I] How to Reflect and Focus X-rays ? • Total reflection 全反射 Visible light 可視光 X-ray n < 1 refractive index（屈折率) n > 1 • Paraboloid collector • Wolter Type I Optics Focal plane 焦点面 Optical axis 光軸 Hyperboloid 回転双曲面 Paraboloid 回転放物面 Parabolloid 回転放物面

  34. [S] Closed-loop Attitude Control (姿勢制御） Target attitude Error signal 比較 Actuators • Magnetic torquers • Momentum wheels • Gas jets • … Automated Attitude Calclation Attitude Sensors • Star tarckers • Sun sensors • Horizon sensors • Gyroscopes • … Dynamical response of the satellite

  35. [A] Highlights of the Soft X-ray Telescope • 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? X-ray colona Long-term variation of the coronal activity 宇宙科学研　http://www.isas.ac.jp

  36. 15-23 keV 30arcsec 6000 14-23 keV 33-53 keV 0 33-53 keV Solar rim 600 0 53-93 keV 600 0.22-1.4 MeV 0 2000 1000 6.2-8.8 MeV 0 200 100 １minutes 10-30 MeV 0 80 1998 August 18, UT 22h 16m 40 36 0 0.5秒ごとの53-93 keV 画像 [A] Highlights of the Hard X-ray Telescope • The largest gamma-ray flare ever detected with Yohkoh • Evidence of gamma-ray emission from loop-top regions • Particles are accelerated at the loop top? 0.5秒ごとの53-93 keV 画像

  37. Cool plasma stream Hardest, impulsive gamma-rays Accelerated electrons Softer, gradual gamma-rays Hard X-rays [A] A Possible Scenario of Acceleration Reconnection point Magnetic field line Main acceleratin regoin photosphere

  38. 6.ASCA 飛鳥Advanced Satellite for Cosmology and Astrophysics • 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., PASJ46, L37(1994) 重量 Weight： 417 kg 近地点 Perigee: 520 km 遠地点 Apogee: 620 km

  39. CCD TEC Heat sink sunshade Plastic (high far-IR emissivity) Silver or Alminium (low near-IR absorptivity) [S] Radiative Cooling of Instruments Instruments such as CCDs may be cooled to 〜100 ℃ by using thermoelectric cooler (TEC), heat pipe, and radiator panels. Radaitor panel Heat pipe

  40. [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 increase the soft X-ray transmission. • The depletion layer as thick as possible, to increase the 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.

  41. Relativistic electrons with Lorentz factor γ Synchrotron radiation at ν〜106B[μG]γ2 Hz Dual Doppler-shifted atomic lines from SS433 (Kotani et al. PASJ46, L147, 1994 ) Inverse Compton emission at ν〜 νsoftγ2 [E] Dual Scientific Merits of ASCA (2) Hard X-ray imaging in energies above 〜2 keV (particularly non-thermal emission with the GIS) Superior energy resolution (with particularly the SIS) Collision with soft photons, particularly of the CMB Gyration around magnetic fields

  42. [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]

  43. Epilogue • 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.

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