# Presentation: 394449

## Growth of Massive Black Holes in Active Galactic Nuclei

- Roger Blandford
- KIPAC, Stanford

- Santa Fe

- 11 vii 2006

## Quasars for the Impatient

**Quasars for the Impatient**

- Intensity / Eddington

- <10-6

- ~0.01

- ~0.1

- ~1.0

- soft
- spectrum

- hard
- spectrum

- Quiescence

**Steady Jet**

**Intermittent Jet**

*Fender*

- Santa Fe

- 11 vii 2006

## Assumptions and Notation

- Astrophysical holes depend upon mass and spin
- Charge irrelevant
- Time measured in Salpeter times
- 400Myr
- Mass increases monotonically through accretion
-  (t)=ln(M/106Msun)
- Normalized accretion rate
- '(t)=d/dt=M’/ MEdd’
- Normalized supply rate
- '(t)=Q/M
- Dimensionless angular momentum
- t=Jc/GM2 =a/m; 0<<1

- Santa Fe

- 11 vii 2006

## Individual AGN

- Geometrical Scaling Relations
- M is just a scale
- Autonomous relations, independent of time
- '(')=> '(')
-  ddt='(')
- Normalized luminosity of disk, wind, jet
- Use total (bolometric) power
- Spectrum depends upon M
- Efficiency
- d,w,j='d,w,j(')=Ld,w,j /LEdd

- Santa Fe

- 11 vii 2006

## Model for Mass Supply

**Model for Mass Supply**

- Velocity dispersion 
- ~sound speed
- Disk begins at accretion radius
- Ra=GM/2~(c/)2m
- Stellar mass dominates for R>Ra
- Supply rate
- Q=(3/G)fgas
-    =4x1029(/300kms-1)3 fgas  g s-1
- '=2x106(/300kms-1)3 fgas  M6-1
- Ignores stellar sources and sinks
- Could be modulated by outflows and radiative pre-heating
- Feast or famine
- Inflow time
- Ra/~2x10-3M6Myr
- Mass increment
- ~fgas

- Ra

- Santa Fe

- 11 vii 2006

## Steady, Radiative Accretion

**Steady, Radiative Accretion**

- Thin disk, slow inflow v, mass per radius 
-     Torque G, Specific angular momentum l
-     Angular velocity ,  Energy  e = -l/2

**Local energy radiated is **
**3 x the binding energy released**

- Santa Fe

- 11 vii 2006

## Adiabatic Disks

**Adiabatic Disks**

- Outflows,winds, jets remove, mass, angular momentum, energy
- Thick disks
- Ion pressure
- Dissipated energy heats ions
- Poor ion-electron coupling
- Cold electrons don’t radiate
- Radio galaxies
- Radiation pressure
- Thomson scattering optical depth
- Photons trapped within
- Advected inwards
- BALQs

- Santa Fe

- 11 vii 2006

## Torque Transports Energy

**Torque Transports Energy**

- Angular Momentum Transport

- Energy Transport

- Bernoulli Function

- Energy transport from small r
- by torque unbinds gas at large r.

- Santa Fe

- 11 vii 2006

## ADiabatic Inflow-Outflow Solution

- Liberated binding energy carried off in a wind
- Removes mass, angular momentum and energy
- Mass accretion<<mass supply
- Hydromagnetic for low mass supply rate
- Radiatively driven for high mass supply rate?
**Accretion** efficiency always high ~ 0.1c2
- May be large contribution from spin of hole
- Nonthermal emission

- Santa Fe

- 11 vii 2006

## Model for Mass Accretion

- Slow accretion
- Ion-dominated thick disk
- ’=0’2/'c; 'c~1, depends on 
- Moderate accretion
- Thin radiative disk
- ’=0’
- Fast accretion
- Radiation-dominated thick disk
- ’=10

- ’

- 0’

***t***

******

******

- Santa Fe

- 11 vii 2006

## Emission model 

- Disk
- Expect that disks are pretty dissipative close to hole due to magnetic interactions
- d~(0.1+0.2Min[',]
- Fast accretors have d~1-3
- Wind
- Outflows carry off energy that cannot be radiated
- BALQ
- w~0.1(0’/’-1)
- Jet
- Associated with spinning black hole
- FR2 Jet > Wind
- FR1 Jet < Wind
- RLQ are minority of fast accretors that have high spin

- Santa Fe

- 11 vii 2006

## Archimedean Disks

- rout ~ (c/vout)2rin ~106rin.

*RB, Wang et al*

- Santa Fe

- 11 vii 2006

## Archimedean Disks

- rout ~ (c/vout)2rin ~106rin.

- Santa Fe

- 11 vii 2006

## Twister

**Twister**

- Mean field configuration is MRI unstable.
- Growth time ~ Period
-   H
**Conjecture**
- Mean field is responsible for the torque
- Random component is responsible for effective
-          resistivity and viscosity

**Test with numerical simulations**

- Santa Fe

- 11 vii 2006

## Archimedean Disks

**Archimedean Disks**

- rout ~ (c/vout)2rin ~106rin.

- Net radial field
- Conservative disk
- Ignore irradiation,
- self-gravitation etc

**Magnetic pressure dominates and field lines escape**

- Santa Fe

- 11 vii 2006

## Inner Disk - Black Holes

**Inner Disk - Black Holes**

- 

******B>**

- J

**.**

- Santa Fe

- 11 vii 2006

## Pictor A

**Current Flow**

**Nonthermal emission **
**is ohmic dissipation **
**of current flow? **

- Electromagnetic Transport
- 1018 not 1017 A
- DC not AC
- No internal shocks
- New particle acceleration mechanisms

**Pinch stabilized by **
**velocity gradient **
**Equipartition in core**

*Wilson et al*

- Santa Fe

- 11 vii 2006

## Spin Evolution

- Fluid angular momentum, magnetic torque
- Spinning holes accrete less specific angular momentum
- Retrograde holes accrete more (negative) angular momentum
- For slow spins jet angular momentum loss ~ 2
- Suppression at high spin
- ’=[+/-(3-/+1-)-2-2(1-)1/4fmag(’,)]’

- Santa Fe

- 11 vii 2006

## Evolution of Population

**Evolution of Population**

- Distribution function
- N(M6,t)
- Source function
- S(M6,,t)
- Spin up and down
- Fokker-Planck formalism (cf Marconi)

- Santa Fe

- 11 vii 2006

## Self-Similar, Fluid, Disk-Wind Model

- Disk
- Bound
- Hoiland=> Gyrentropic
- Meridional Circulation
- Inflow
- Relativistic treatment of inner regions
- Matched to transition radius
- Wind
- Thermal Front
- Adiabatic Wind
- Jet
- Evacuated cone

*RB & Begelman*

- Santa Fe

- 11 vii 2006

## Jet Fuel

**Jet Fuel**

- Relativistic Jets Powered by Black Hole Spin
- Thick disks spin down hole electromagnetically
- Thin disks spin up hole through accretion

- 10

- 1

- 0.1

- Thick Ion Disk
- Spin Down, Steady,
- Radio Loud

- Thin Radiative Disk
- Spin Up
- Radio Quiet

- Thick Radiation Disk
- Spin Up/Down
- Unsteady

- Jet properties depend
- upon mass supply rate
- and history.

- Santa Fe

- 11 vii 2006

## Jet Fuel

**Jet Fuel**

- Relativistic Jets Powered by Black Hole Spin
- Thick disks spin down hole electromagnetically
- Thin disks spin up hole through accretion

- 10

- 1

- 0.1

- Jet properties depend
- upon mass supply rate
- and history.

*Width ~****M*

- Santa Fe

- 11 vii 2006

## IGN

- Magnetic reservoir
- Ohmic dissipation
-  . B constant

- Sgr A* Jet?
- B~100G,
- ~3PV
- I~300TA
- LEM~1030W

- Baganoff, Morris etal

- Ljet  ~ 1029 W?

- Llobe  ~ 1032 W?

- Santa Fe

- 11 vii 2006

## Hydromagnetic Disks

- Magnetorotational Instability

*Hawley et al*

- Santa Fe

- 11 vii 2006

## Asymmetric Outflows/Jets

**X**

**Can you measure the toroidal field pattern?**

**Even Parity**

**Odd Parity**

**Mixed Parity**

- Santa Fe

- 11 vii 2006

## Elementary confinement by toroidal field

- Toroidal magnetic field B in jet frame
- Current I in rest frame
- I=2rB/0
- Static equilibrium
- Jet Power
- Typically Mech power~ 3-10 EM power

- Santa Fe

- 11 vii 2006

## Simple Example

- L=Lmech+Lem=3 x 1045(Ioo/1EA)2 erg s-1
- Ioo=0.15(B/1mG)(r/10pc)EA
- Emission Model
- Faraday Rotation Model
- VIPS VLBI survey of 1000 radio sources

****

**I/I****00**

**P/P****0**

********

************

**L****mech**

**L****em**

- Santa Fe

- 11 vii 2006

## Summary

- Underfed and overfed accretion may be demand-limited
- Radiatively inefficient with respect to gas supply
- Energy (and angular momentum) carried off by MHD wind?
- Hole spun down; powers relativistic jets
- Radio-loud quasars?
- Well-fed accretion conservative
- Radiatively efficient
- Hole spun up
- Weak outflows jets
- May be significant radial disk field
- Dipolar, current
- Quadrupolar field
- More efficient energy extraction?
- Pinched relativistic jets are mostly mechanical
- Seek polarization pattern using VLBI
- Need many more numerical simulations!

- Santa Fe

- 11 vii 2006