Growth of Massive Black Holes in Active Galactic Nuclei

1
Growth of Massive Black Holes in Active Galactic
Nuclei

• Roger Blandford
• KIPAC, Stanford

2
Quasars for the Impatient
Fender
Intermittent Jet
1.0
0.1
Steady Jet
0.01
Intensity / Eddington
lt10-6
Quiescence
soft spectrum
hard spectrum
3
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?/dtM/ MEdd
• Normalized supply rate
• ??'(t)Q/M
• Dimensionless angular momentum
• ??t?Jc/GM2 a/m 0lt?lt1

4
Individual AGN

• Geometrical Scaling Relations
• M is just a scale
• Autonomous relations, independent of time
• ??'(?'??)gt ?'(??'??)
• 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

5
Model for Mass Supply

• Velocity dispersion ?
• sound speed
• Disk begins at accretion radius
• RaGM/?2(c/?)2m
• Stellar mass dominates for RgtRa
• 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
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Steady, Radiative Accretion

• Thin disk, slow inflow v, mass per radius m
• Torque G, Specific angular momentum l
• Angular velocity W, Energy e -Wl/2

Local energy radiated is 3 x the binding energy
released
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Adiabatic Disks

• Outflows,winds, jets remove, mass, angular
  momentum, energy
• Thick disks
• Ion pressure
• Dissipated energy heats ions
• Poor ion-electron coupling
• Cold electrons dont radiate
• Radio galaxies
• Radiation pressure
• Thomson scattering optical depth
• Photons trapped within
• Advected inwards
• BALQs

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Torque Transports Energy
Angular Momentum Transport
Energy Transport
Energy transport from small r by torque unbinds
gas at large r.
Bernoulli Function
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ADiabatic Inflow-Outflow Solution

• Liberated binding energy carried off in a wind
• Removes mass, angular momentum and energy
• Mass accretionltltmass 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

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Model for Mass Accretion

• Slow accretion
• Ion-dominated thick disk
• ??02/?'c ?'c1, depends on ?
• Moderate accretion
• Thin radiative disk
• ??0
• Fast accretion
• Radiation-dominated thick disk
• ?10

?0
??
?
?
t
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Emission model

• Disk
• Expect that disks are pretty dissipative close to
  hole due to magnetic interactions
• ?d(0.10.2??Min?',?
• Fast accretors have ?d1-3
• Wind
• Outflows carry off energy that cannot be radiated
• BALQ
• ?w0.1(?0/?-1)
• Jet
• Associated with spinning black hole
• FR2 Jet gt Wind
• FR1 Jet lt Wind
• RLQ are minority of fast accretors that have high
  spin

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Archimedean Disks

• rout (c/vout)2rin 106rin.

RB, Wang et al
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Archimedean Disks

• rout (c/vout)2rin 106rin.

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Twister

• Mean field configuration is MRI unstable.
• Growth time Period
• l lt H
• Conjecture
• Mean field is responsible for the torque
• Random component is responsible for effective
• resistivity and viscosity

Test with numerical simulations
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Archimedean Disks

• rout (c/vout)2rin 106rin.

Net radial field Conservative disk Ignore
irradiation, self-gravitation etc
Magnetic pressure dominates and field lines escape
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Inner Disk - Black Holes
ltBgt
W
J
.
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Pictor A
Wilson et al
Electromagnetic Transport 1018 not 1017 A DC not
AC No internal shocks New particle acceleration
mechanisms
Current Flow
Nonthermal emission is ohmic dissipation of
current flow?
Pinch stabilized by velocity gradient
Equipartition in core
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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(?,?)?

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Evolution of Population

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

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Self-Similar, Fluid, Disk-Wind Model
RB Begelman

• Disk
• Bound
• Hoilandgt Gyrentropic
• Meridional Circulation
• Inflow
• Relativistic treatment of inner regions
• Matched to transition radius
• Wind
• Thermal Front
• Adiabatic Wind
• Jet
• Evacuated cone

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Jet Fuel
Thick Radiation Disk Spin Up/Down Unsteady

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

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Thin Radiative Disk Spin Up Radio Quiet
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Jet properties depend upon mass supply rate and
history.
0.1
Thick Ion Disk Spin Down, Steady, Radio Loud
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Jet Fuel

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

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1
Width WM
Jet properties depend upon mass supply rate and
history.
0.1
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IGN
Baganoff, Morris etal
Sgr A Jet? B100G, F3PV I300TA LEM1030W
Ljet 1029 W?
Magnetically-pinched current? Magnetic
reservoir Ohmic dissipation W . B constant
Llobe 1032 W?
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Hydromagnetic Disks

• Magnetorotational Instability

Hawley et al
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Asymmetric Outflows/Jets
X
Even Parity
Odd Parity
Mixed Parity
Can you measure the toroidal field pattern?
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Elementary confinement by toroidal field

• Toroidal magnetic field B in jet frame
• Current I in rest frame
• I2?r?B/?0
• Static equilibrium
• Jet Power
• Typically Mech power 3-10 EM power

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Simple Example
Lmech
?????
?
I/I00
P/P0
Lem
????

• LLmechLem3 x 1045(Ioo/1EA)2 erg s-1
• Ioo0.15(B/1mG)(r/10pc)EA
• Emission Model
• Faraday Rotation Model
• VIPS VLBI survey of 1000 radio sources

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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!