1. Magnetized (“ real ”) Accretion Flows Roman Shcherbakov, 5 December, 2007

2. Specifics of Magnetized accretion Coulomb mean free path > size of the flow Proton gyroradius < size of the flow collisionless MHD (not full kinetic theory) collisionless MHD Plasma beta parameterMagnetization in the real flows, thus magnetic field is usually dynamically important

3. Spherical accretion. Problem

4. Spherical accretion. Setup Outer magnetization radius of influence of BH/NS – Compression maintains turbulence Balance between build-up and dissipation Externally supported Isotropic turbulence Supported by compression Non-Isotropic turbulence

5. Spherical accretion. Accretion rate Relativistic EOS Larger inhibition Larger magnetizaton Smaller accretion rate outer magnetization normalized accretion rate Larger back-reaction

6. Spherical accretion. Magnetization

7. Magnetorotational Instability

8. Evolution of MRI z

9. Transport of angular momentum Reynolds stress (>0) Maxwell stress (<0) Schwarz inequality Also Upper boundary for stress stress is important, angular momentum can go up and be carried away by wind

10. vs Kato, Yoshizawa, 1995PASJ...47..629K turbulent stress coefficient energy generation coefficient

11. Evolution of magnetization

12. Evolution of angular momentum alpha

13. Density contours CK Chan, 2007

14. Analytic closures Pessah, CK Chan 2007

15. Krolik, 2005

16. Hawley, Balbus 2002

17. Conclusions Magnetic field is an essential ingredient of ANY astrophysical flow Realistic accretion pattern is likely to be very complicated, outflows, jets Alpha parameter should at least be a function of radius, but apparently one parameter is not enough Zero torque condition at ISCO is not applicable Some analytic calculations, but progress is made through simulations