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 ＠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 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)

Model for Emission Mechanism Internal Shock Model Photospheric Emission Model photosphereInternal shock External shock γ γ ・ Low efficiency for gamma-ray production ・ Clustering of peak enegy ~ 1MeV (e.g., Rees & Meszaros 2005, Pe’er et al.2005, Thompson 2007) flaw Natural consequence of fireball model ・ High radiation efficiency ・ Difficult to model hard spectrum in low energy band (α)

Difficulty in photospheric emission model f ν ~ν 0 f ν ~ν -1.2 non-thermal spectrum E (MeV) Broadening from the thermal spectra is required

Dissipative process Giannios & Spruit 2007, Giannios 2008, 2012 Magnetic recconection Repeated Shock Ioka , Lazzati & Begelman 2010 Proton-neutron collision Derishev 1999, Beloborodov 2010, Vurm+2011 high energy tail is reproduced by the relativistic pairs produced by dissipative processes Beloborodov 2010 relativistic pairs upscatter thermal photons assumption 1D steady spherical outflow

Geometrical brodening Structure of the jet can give rise to the non-thermal spectra Multi-dimensional structure of jet may be a key to resolve the difficulty Mizuta+2011 Ioka+2011 spectrum broadens even in the absence of relativistic pairs

Our focus: Effect of the jet structure on the emission Find the jet structure that can explain the observation Stratified Jet structure  ~1 photosphere  0 >  1 Accleration region Photons gain energy by crossing the boundary layer 2 effects on the spectra (I) multi-color effect (II) Fermi acceleration of photons Propagation of photons are solved by Monte=Carlo method νf ν Spine Sheath see also Lundman

r Spine (θ<θ 0 ) Sheath (θ 0 <θ<θ j ) r in (τ>>1) r out (τ<<1) riri  r 00 00 r s1 r s0 11 11 Calculation Range r in ＝ r s1 << R ph r out = 500R ph (τ~2×10 -3 ) :photospheric radius Two-component jet Fireball model

r Spine (θ<θ 0 ) Sheath (θ 0 <θ<θ j ) r in (τ>>1) r out (τ<<1) riri r 00 00 r s1 r s0 11 11 Initial Condition Inject thermal photons at the inner boundary L in = 5.4×10 52 r 8 2/3  400 8/3 L 53 1/3 (r in /10 11 cm) -2/3 erg/s T in = 0.9 r 8 1/6  400 8/3 L 53 -5/12 (r in /10 11 cm) -2/3 keV Two-component jet  Fireball model

E max =  0 m e c 2 Klein-Nishina cut-off Spine Sheath Two-component jet  0 =400  j =1°  0 =0.5°  obs =0.4° Thermal + non-thermal tail Non-thermal tail becomes prominent as the relative velocity becomes larger |θ obs - θ 0 | <  -1 ～ 0.14°  But limited only for narrow range of observer angle

dθ  0 =400  1 =100 Interval of velocity shear dθ < 2  -1 high energy spectra (β) is reproduced by accelerated photons β= -2.3 α=-1 Low energy spectra (α) is reproduced by multi-color effect see also Lundman Multi-component jet E max =  0 m e c 2 ~ 100MeV Cut off at ~ 100 MeV

dθ  0 =400  1 =100 Multi-component jet Face on view of jet Simulation by Dr. Matsumoto ジェットの断 面

DOP （％）＝ (I + - I - ) / (I + + I - ) dθ  0 =400  1 =100 multi-component jet that reproduces Band spectra High polarization degree (>10%) is predicted polarization  obs (degree) 0% Future missions such as Tsubame and POLAR may probe such an emission See also Lundman

L j = erg/s  j = 5°  j = 5  ｈ = 500 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 親星モデル 16TI （ Woosley & Heger 2006 ） M * ~14Msun R * ~ 4×10 10 phase ジェット 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 輻射輸送計算    inj >> 1    = 1 t=4s t=300s Ｒ inj = cm モデル１： 定常インジェク ション モデル２： 歳差運動

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 β ＝ -2.5 ４°４° α ＝ -1 ローレンツ因 子 log  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。 モデル１ 定常インジェクション

α ＝ -1 β ＝ -2.5 ローレンツ因 子 log  歳差運動の周期が光度曲 線にそのまま反映される モデル２ 歳差運動 (t pre =2s θ pre = 3°)

Summary Structured jet can produce a power-law non-thermal tail above the peak energy - - Futrure works Photon accelerations in various structures with high spacial resolution calculation shocks, turbulence - Polarization signature is not negligible in the structured jet 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 High DOP (>10%) is predicted for the jet structure that reproduces Band function