Bondi/Hoyle and Shakura/Sunyaev - Max-Planck-Institut für ...

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Mass conservation • Steady-state situation: Mass inflow (at infinity) per time is mass outflow (at the CO) per time • Divide the disk into cylindrical rings; define the surface density of any ring by Σ(r) ≡ 2h(r)ρ(r) • Continuity equation demands that the flow through each cylinder at r is independent of r: 2πrΣvr = ˙ M = const 19
Angular momentum conservation • Motion on Keplerian orbits ⇒ accretion rate determines angular momentum inflow rate at r J ˙+ = ˙ M √ GMr • Consumed rate of angular momentum at the CO: ˙ J − ≤ ˙ M GMrI • Let fΦ be the viscous stress along the normal eΦ • Torque is (force along eΦ / area)·(area)·r and also equal to the difference between ˙ J + and ˙ J − : (fΦ)(2πr · 2h)(r) = ˙ J + − ˙ J − 20
Page 1 and 2: Accretion: Bondi/Hoyle and Shakura/
Page 3 and 4: Literature • This talk is based o
Page 5 and 6: Accretion onto compact objects •
Page 7 and 8: Models of accretion • Analytical
Page 9 and 10: 2. Spherical accretion 8
Page 11 and 12: Flow description • 1D radial flow
Page 13 and 14: • u(r) at small radii: free-fall
Page 15 and 16: 3. Disk accretion 14
Page 17 and 18: Disk accretion: General features
Page 19: Sketch of a thin accretion disk 18
Page 23 and 24: Vertical momentum conservation •
Page 25 and 26: Viscosity law • Several physical
Page 27 and 28: Radiative transport • Transport f
Page 29 and 30: Structure of the solution • The s
Page 31 and 32: 4. General relativistic torus accre
Page 33 and 34: The torus (thick disk) model • As
Page 35: Summary • Accretion is inflow of

Bondi/Hoyle and Shakura/Sunyaev - Max-Planck-Institut für ...

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