1. Radiation Hydrodynamic simulations of super-Eddington Accretion Flows super-Eddington Accretion Flows Radiation Hydrodynamic simulations of super-Eddington Accretion Flows super-Eddington Accretion Flows Ken OHSUGA Rikkyo University, Japan ① Super-Eddington accretion flows with photon-trapping (Ohsuga et al. 2005, ApJ, 628, 368) ② Limit-cycle oscillations driven by disk instability (Ohsuga 2006, ApJ, 640, 923)

2. Super-Eddington disk accretion flows The super-Eddington disk accretion (Mdot > L E /c 2 ; L E :Eddington luminosity) is one of the important physics for formation of the SMBHs. The super-Eddington accretion might be an engine of the high L/L E objects, ULXs, GRBs, NLS1s, ….. Mass outflow and radiation of the super-Eddington accretion flow are thought to affect the evolution of the host galaxies. To understand the super-Eddington accretion is very important ! 1. Super-Eddington Accretion Flows In the super-Eddington accretion, the radiation pressure affects the dynamics of the flow. Multi- dimensional effects are important.

3. BH Accretion Disk Viscous Heating Photon-Trapping Photons fall onto BH with accreting gas Outflow Gas Radiation Energy We investigate the super-Eddington disk accretion flows by performing the 2D Radiation Hydrodynamic simulations. *Slim disk model (1D) cannot correctly treat the multi-dimensional effects

4. Basic Equations of Radiation Hydrodynamics Continuity Equation ・・・・・・・ Equation of Motion ・・・・・・・ Gas Energy Equation ・・・・・・ Radiation Energy Equation ・・ Radiation Force Viscosity Absorption/Emission Radiative Flux Equation of State: p=(  1)e,  =5/3 Radiation fields (F 0, P 0 ) ： FLD approximation  -viscosity ：  P (  =0.1, P:total pressure) Absorption coefficient(  =  ff +  bf ),  ff : free-free absorption,  bf :bound-free absorption (Hayashi, Hoshi, Sugimoto 1962)

5. Numerical Method Explicit-implicit finite difference scheme on Eulerian grid (Spherical coordinates : 96 x 96 mesh) Axisymmetry with respect to the rotation axis Size of computational domain: 500r s Initial condition: atmosphere (no disk) Free outer boundary & absorbing inner boundary Injection BH r/rs r/rs z/rs z/rs 500 Matter (0.45 x Keplerian angular momentum) is continuously injected into the computational domain from the outer disk boundary. Parallel computing with PC cluster

6. Radiation Energy DensityGas Density The quasi-steady structure of the super-Eddington accretion flows is obtained by our simulations.

7. Density & Velocity fields Outflow KH instability Quasi-steady Structure Mass-Accretion Rate Mass-accretion rate decreases near the BH. BH r/rs r/rs z/rs z/rs Ohsuga et al. 2005, ApJ, 628, 368 Bubbles & Circular Motion

8. Radiation Pressure- driven wind Radiation Pressure- dominated Disk High Temperature Outflow/Corona Radiation Energy Density Radiation Pressure Gas Pressure Gas Temperature Radial Velocity Escape Velocity Low Temperature Disk Quasi-steady Structure

9. Photon-Trapping Mass-accretion rate Luminosity [L/L E ] 2D RHD simulations BH z/rs z/rs r/rs r/rs Transport of Radiation Energy in r-direction Radiation energy is transported towards the black hole with accreting gas (photon-trapping). We verify that the mass-accretion rate considerably exceeds the Eddington rate and the luminosity exceeds L E. Radiation Kinetic (Outflow) Viscous Heating

10. Viewing-angle dependent Luminosity & Image BH  The observed luminosity is sensitive to the viewing-angle. It is much larger than L E in the face-on view. Intensity Map Apparent Luminosity Density 4  D 2 F(  )/L E Our simulations [][] (Intrinsic Luminosity ~3.5L E )

11. 2. Limit-Cycle Oscillations Timescale of the luminosity variation is around 40s. The disk luminosity oscillates between 2.0L E and 0.3L E (Yamaoka et al. 2001). The intermittent JET is observed. Janiuk & Czerny 2005 GRS1915+105 (micro quasar) L~2L E L~0.3L E 40s

12. Disk instability in the radiation-pressure dominant region. If the mass-accretion rate from the disk boundary is around the Eddington rate, Mdot  L E /c 2, the disk exhibits the periodic oscillations via the disk instability. stable unstable Surface density Mass-accretion rate High state Low state This Topic (Mdot=10 2 L E /c 2 ) Previous Topic (Mdot=10 3 L E /c 2 ) We investigate the time evolution of unstable disks by performing the 2D RHD simulations.

13. Sub-Eddington state It is found that the disk structure changes periodically. Super-Eddington state outflow

14. The disk luminosity oscillates between 0.3L E and 2.0L E, and duration time is 30-50s. Jet appears only in the high luminosity state. These results are nicely fit to the observations of GRS 1915+105. Mass accretion rate Outflow rate Trapped luminosity Luminosity Ohsuga 2006, ApJ, 640, 923

15. Conclusions(1) : super-Eddington accretion flow; Mdot >> L E /c 2  The mass accretion rate considerably exceeds the Eddington rate.  The black hole can rapidly grow up due to disk accretion (Mdot/M~10 6 yr).  The luminosity exceeds the Eddington luminosity. The apparent luminosity is more than 10 times larger than L E in the face-on view.  The luminosity of the ULXs can be understood by the super-Eddington accretion flow.  The thick disk forms and the complicated structure appears inside the disk. The radiation-pressure driven outflow is generated above the disk.  We found that the photon-trapping plays an important role. Conclusions(2) : limit cycle oscillations; Mdot  L E /c 2  The resulting variation amplitude (0.3L E ⇔ 2.0L E ) and duration (30-50s) nicely fit to the observations of microquasar, GRS 1915+105.  The intermittent jet is generated.  The physical mechanism, which causes the limit-cycle oscillations, is the disk instability in the radiation-pressure dominant region.