マグネター研究の現状 ・観測のまとめ ・エネルギー源 ・太陽フレアモデルとの比較 ・定常X線・γ線の放射モデル ・QED 効果 ・QPO ・今後の課題 SGR1900+14 Ulysses data for the August 1998 giant flare SGR 1806-20 ・recurrent bursts duration ~0.1 s rise times < 10 ms eg ~30 keV (kTBB~9 keV) LX (102 - 104) Ledd (magnetic confinement) energy release Q ~< 1042 erg association SNRs (1SGR, 3AXPs) ・giant outbursts duration ~ 200, ~300 s initial spike LX ~106 Ledd, Q >1044 erg, kT~300, 500 keV tail Q ~ 1044 erg, kT~20, 30 keV ・hyper flare initial spike duration ~0.2 s rise times < 1 ms eg kTBB~175 keV LX ~109 LEdd energy release Q 5 × 1046 erg tail duration 380 s eg kTBB~ 4-9 keV energy release Q 1044 erg ・persistent component from SGRs & AXPs LX 1034 - 1036 erg spectrum BB(~0.5keV) + PL(2-3) pulsation 5 - 12 s p-dot 10-12 - 10-10 s/s τsd 103 - 105 yrs B(dipole field) 6× 1013 - 1015 G ・energy source Ý L I X ×Rotational energy ×Thermal energy ×Strain energy ○ magnetic energy 太陽フレアモデルの応用 ・パーカー不安定による磁束管の浮上 ・対流による磁束管の捩り上げ（エネルギーの蓄積） ・リコネクションを伴う不安定性の発生（エネルギー解放） Model of repeated soft gamma ray bursts 10 km magnetar [Thompson and Duncan, MNRAS, 1995] magnetar (Duncan) ・unwinding and twist B 4 4 1015 140.4 G B B plastic unwinding of the internal field slow, plastic motion flux tube rise reconnection twist in the magnetosphere ・tearing instability + reconnection Alfven time Resistive time L A ~ 3105 L6 s c 4 o L2 2 R ~ 3L 6 s 2 c 2 3 / 2 ~ 10 L6 s t A R mode growth time Tearing Repeated bursts vs. Giant flares Repeated bursts Giant flares (Duncan) Localized energy release Global energy release due to entire crustcore magnetic instability [Thompson and Duncan, MNRAS, 1995 / ApJ 2001] ・X-ray and γ-ray emission (Thompson and Duncan, MNRAS,1995) Initial spike ---> jet Pulsating tail ---> evaporating trapped fireball Magnetic reconnection, or Nonlinear damping of waves A photon pair plasma (e-+e+) Persistent component Gotz et el., 2007 2006 Input energy --> 99% -->neutrino Q ~ 1049 - 1050 ergs Persistent Hard X-Ray Emission A QED Model fast MHD wave e+- pair production synchrotron emission hard X rays Heyl & Hernquist 2005 QED Effects ・ pair creation ・photon splitting BQED m2c 3 /e 4.4 1013 G Baring & Harding1998 Camilo et al. 2000 QPO in the hyper flare of SGR 1806-20 (P=7.56 s) 92.5 Hz 50 Hz ~18Hz, ~30Hz at t=170-220 s at t=45-175 ms and at t=430-567 ms at t~200-300 s Global seismic vibration model The ratio of first radial overtone to fundamental frequency 0 l(l 1) R ~ n 3n R 30Hz (l 2,n 0) 625 Hz (n 1,l ~ n) ---> ---> R/R 0.06 0.1 R/R 0.127 ・振動数 よく合っている ・SGR 1806-20 の18Hz, 26Hzはでない ・SGR 1806-20とSGR 1900+14の振動数の違い ---> M, R, B の違い ・SGR 1806-20 30Hz fundamental 625Hz first overtone ---> H/R ~ 0.1-0.13 ・strange star --->much thinner crust ---> >>625Hz ・重力波--->弱くadvanced LIGOでも無理 課題 ・core-crust coupling ・dipole field and toroidal internal field To be studied ・formation of ultra-strong magnetic fields ・unwinding and twist ・reconnection & particle acceleration ・emission & spectra
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