構造を持った相対論的ジェット からの光球面放射 Hirotaka Ito RIKEN Collaborators Shigehiro Nagataki (RIKEN), Jin Matsumoto (RIKEN), Shiu-Hang Lee (JAXA), Masaomi Ono (Kyushu Univ.), Jirong Mao (Kyushu Univ), Asaf Pe’er (UCC), Akira Mizuta (RIKEN), Alexei Tolstov (IPMU), Maria Dainotti (RIKEN), Shoichi Yamada (Waseda Univ.), Seiji Harikae (Mitubishi UFJ) ＠コンパクト連星合体からの重力波・電磁波放射とその周辺領域2015 /2/13 Model for Emission Mechanism Internal Shock Model flaw ・Low efficiency for gamma-ray production ・Difficult to model hard spectrum in low energy band (α) Photospheric Emission Model Natural consequence of fireball model (e.g., Rees & Meszaros 2005, Pe’er et al.2005, Thompson 2007) ・High radiation efficiency ・Clustering of peak enegy ~ 1MeV γ photosphere γ Internal shock External shock Difficulty in photospheric emission model non-thermal spectrum E (MeV) Broadening from the thermal spectra is required Dissipative process high energy tail is reproduced by the relativistic pairs produced by dissipative processes Magnetic recconection Giannios & Spruit 2007, Giannios 2008, 2012 Repeated Shock assumption 1D steady spherical outflow Ioka + 2007, Lazzati & Begelman 2010 Proton-neutron collision Derishev 1999, Beloborodov 2010, Vurm+2011 relativistic pairs upscatter thermal photons Beloborodov 2010 Geometrical brodening Structure of the jet can give rise to the non-thermal spectra Mizuta+2011 spectrum broadens even in the absence of relativistic pairs Ioka+2011 Multi-dimensional structure of jet may be a key to resolve the difficulty Our focus: Effect of the jet structure on the emission Find the jet structure that can explain the observation Stratified Jet structure 2 effects on the spectra (I) multi-color effect see also Lundman + 2013 (II) Fermi acceleration of photons Accleration region Photons gain energy by crossing the boundary layer photosphere νfν t~1 Spine Sheath G0 > G1 n Propagation of photons are solved by Monte=Carlo method Two-component jet Spine (θ<θ0 ) Sheath (θ0<θ<θj ) Calculation Range rin rout (τ<<1) ＝ rs1 << Rph rout = 500Rph(τ~2×10-3) :photospheric radius rin (τ>>1) r h0 G Fireball model ri G0 G1 h1 rs1 rs0 r Two-component jet Spine (θ<θ0 ) Sheath (θ0<θ<θj ) Initial Condition Inject thermal photons at the inner boundary rout (τ<<1) rin (τ>>1) r Tin = 0.9 r81/6G4008/3 L53-5/12 (rin/1011cm)-2/3 keV Lin = 5.4×1052 r82/3G4008/3 L531/3 (rin/1011cm)-2/3 erg/s h0 G Fireball model ri G0 G1 h1 rs1 rs0 r Two-component jet G0=400 qj =1° q0=0.5° qobs=0.4° Thermal + non-thermal tail Spine Sheath Emax = G0mec2 Klein-Nishina cut-off Non-thermal tail becomes prominent as the relative velocity becomes larger -1 ～0.14°G -1 But limited only for narrow range of |θ θ | < G obs 0 400 observer angle Multi-component jet G0=400 G1=100 β= -2.3 α=-1 dθ Emax = G0mec2 ~ 100MeV Interval of velocity shear dθ < 2G-1 high energy spectra (β) is reproduced by accelerated photons Cut off at ~ 100 MeV Low energy spectra (α) is reproduced by multi-color effect see also Lundman + 2013 Multi-component jet G0=400 G1=100 dθ Face on view of jet Simulation by Dr. Matsumoto ジェットの断面 DOP（％）＝(I+ - I-) / (I+ + I-) polarization multi-component jet that reproduces Band spectra G0=400 G1=100 0% dθ qobs (degree) High polarization degree (>10%) is predicted See also Lundman + 2014 Future missions such as Tsubame and POLAR may probe such an emission 三次元相対論的流体シミュレーション ジェットが大質量星の外層を突き破り、光学的に薄くなるまでの過程を計算 t=4s g g 親星モデル 16TI （Woosley & Heger 2006） M* ~14Msun R* ~ 4×1010 cm @presupernova phase ジェット tinj >> 1 t= 1 t=300s g g Lj = 1050 erg/s qj = 5° Gj = 5 Gｈ = 500 Ｒinj = 1010 cm モデル１： 定常インジェクション モデル２： 歳差運動 輻射輸送計算 光学的に十分厚い領域にPlanck 分布の光子を注入し、ジェットから解放され るまでの過程をモンテ=カルロ法を用いて計算 モデル１ 定常インジェクション ローレンツ因子 log G ４° 光子は衝撃波領域を往復す ることによってエネルギーを 得る。 現状 数値拡散によって衝撃波がなまってしまっている => 加速は弱まってしまっている。 α＝-1 β＝-2.5 モデル２ 歳差運動 (tpre=2s θpre = 3°) ローレンツ因子 log G 歳差運動の周期が光度曲 線にそのまま反映される α＝-1 β＝-2.5 Summary - - Structured jet can produce a power-law non-thermal tail above the peak energy non-thermal particle is not required Multi-component jet can reproduce Band function irrespective to the observer angle β is reproduced by the accelerated photons α is reproduced by the multi-color effect Polarization signature is not negligible in the structured jet High DOP (>10%) is predicted for the jet structure that reproduces Band function Futrure works Photon accelerations in various structures with high spacial resolution calculation shocks, turbulence
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