SHIGENOBU HIROSE AND JULIAN H. KROLIK VERTICAL STRUCTURE OF GAS PRESSURE-DOMINATED ACCRTION DISKS WITH LOCAL DISSIPATION OF TURBULENCE AND RADIATIVE TRANSPORT 局所的乱流散逸と輻射輸送を含む ガス圧優勢降着円盤の垂直構造 SHIGENOBU HIROSE AND JULIAN H. KROLIK AND JAMES M. STONE 2006, ApJ, 640, 901

ABSTRACT 降着円盤の local patch の 垂直構造を計算 Relaxation Period 以降 Steady State MRI driven MHD turbulence による heating～Radiative cooling Shearing box で rad-MHD を解くことで self-consistently ３D & Energy Conserving code (元はZEUS３D+FLD module) Relaxation Period 以降 Steady State Photosphere ～7H Conventional analytic model では ～3H 磁気圧がdisk atmosphere を押し上げる 散逸はmidplaneの3H以内に分布 Tgas～Trad(Photoshpere上空でも) Radiation flux は 散逸の変動と時間差0.1-0.2×tcoolで同調 Away from midplane では散逸の変動は強い Top と Bottom surface の flux に大きな asymmetry 散逸に Long-timescale asymmetry Disk全体で垂直方向の energy flow は Radiative Diffusion が dominate

CONTEXT

Shearin box & Grid and Boundary condition Height z outflow boundary 12H 8+8=16H 256 grids H 300rg -H Azimuth y 6.62M◉ periodic boundary 8H 64 grids -12H Radius x H=cg/Ω : scale height 2H 32 grids shearing periodic boundary Δx=Δz=H/16=Δy/2

全エネルギー保存の為の項 Density floor,Energy floor,Velocity capの散逸への寄予は1%程度

(殆ど)Shakura-Sunyaev と同じ F:τ≧1でF0(=σT4) 0.01csのrandom perturbation INITIAL CONDITION (殆ど)Shakura-Sunyaev と同じ F:τ≧1でF0(=σT4) 0.01csのrandom perturbation Pgas Twisted azimuthal flux tube center @ x=z=0, max poloidal B:2.16×106 G, β=24 max MRI wavelength:1.59×106 cm = 7.2 grid Pmag Prad

RESULT 計算時間:60 orbit 5-10 orbit 以降は steady Time-average は 10-60 orbit で取った

Mean Vertical Profiles: Gas Density Exponetial Initial : (nearly)Gaussian

Mean Vertical Profiles: Pressure Pgas dominant Pmag >Prad dominant Pgas-supported disk body + Pmag-supported atmosphere β(mid) ~ 40 β(7H) ~ 0.03 Pgas Pmag Mid plane Prad

Mean Vertical Profile: Temperature Tgas~Trad→LTE Trad~Teff @ high z τ1/4Teffではoverestimate ∵dissipationが強い τ1/4Teff Boundary の影響

Mean Vertical Profile: Dissipation & Stress Midplane 内に Asymmetry structure stressの殆どがmidplane内で生成 α～0.016(vertically integrated) α～1(midplane) α～0.01(|z|>6H)

Thermal Balance: Net Energy Flow Radial surfaceになされる仕事 Magnetic stress:77% Reynolds stress Outgoing energy Radiation diffusion:99.71% Radiation advection:0.14% Mater:0.25% Poynting flux:0.10%

Thermal Balance: Dissipation Rate

Thermal Balance: Cooling f =1/2(Photosphereと定義) Photosphere の Fluctuationは 1-2 orbit f =1/3

Internal Fluctuation: Gas Density and Magnetic Intensity

Internal Fluctuation: Top-Bottom Asymmetry

Internal Fluctuation: Magnetic Field Line Structure Azimuthal が predominant midplane では short scale で tangled (MRI に該当) mid-altitude では smooth high-altitude では disordered (Random fluid motion)