adios revisited mitch begelman jila, university of colorado adios revis it ed
Post on 22-Dec-2015
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TRANSCRIPT
The ADIOS model addresses a fundamental problem in accretion theory…
HOW DOES ROTATING GAS ACCRETE IF IT CAN’T RADIATE
EFFICIENTLY?
ACCRETION REQUIRES TORQUE +
TORQUE TRANSPORTS ENERGY
G
Angular Momentum Flux:
Energy Flux:
outward~Torque MG
outwardG
THE PROBLEM:
IN A THIN ACCRETION DISK:
G
Local rate of energy release:
Local rate of dissipation:
R
GMM
2
R
GMM
23
2/3 of energy dissipated at R transported from <R by viscous
torque
IN A RADIATIVELY INEFFICIENT ACCRETION FLOW:
G
Energy transport from small R by torque unbinds gas at large R
Energy Transport:
Bernoulli Function
02
v B
B~2
h
MG
• Torque a “conveyor belt” for liberated energy
• Flow must find a way to limit energy transported outward from smaller r
– Mass loss or circulation– Small fraction of supplied mass
reaches BH
ADIOS =ADIABATIC INFLOW-OUTFLOWSOLUTION (Blandford & Begelman 99)
1 g of gas accreting at r ~ m
can liberate 1 kg of gas at r ~ 1000 m
THE ADIOS MODEL
Mass Outflow or circulation
Energy 1 R
Ang.Mom. 2/1R
10 n
RM n0BInflow
0B
Mass
Energy
Ang. Mom.
SELF-SIMILAR DISK WINDS
Wind: Inviscid outflow with B < 0
Disk: Viscous flow with B < 0
Jet: Evacuated cone
Entropy increases at disk-wind interface
High shear across wind
No internal mixing across streamlines
Huge parameter space of solutions
Blandford & Begelman 2004
SELF-SIMILAR DISK WINDS
Wind: Inviscid outflow with B < 0
Disk: Viscous flow with B < 0
Blandford & Begelman 2004
Entropy increases at disk-wind interface
SELF-SIMILAR DISK WINDS
Wind: Inviscid outflow with B < 0
Disk: Viscous flow with B < 0
Blandford & Begelman 2004
Entropy increases at disk-wind interface
High shear across wind
No internal mixing across streamlines
Huge parameter space of solutions
0<n<1
TWO-ZONE ADIOS MODEL
Mass Outflow
Energy 1 R
Ang.Mom. 2/1R
10 n
RM n0BInflow
0B
Exchange: Mass
Energy
Ang. Mom.
AVERAGE OVER STREAMLINES
CONSERVE ENERGY, ANG. MOM. IN EACH ZONE
CONSERVE EXCHANGED ENERGY, ANG. MOM.
TWO-ZONE ADIOS MODEL
NO SOLUTION UNLESS:
INCLUDE CENTRAL ENERGY SOURCE n ≈ 1
TOTAL POWER AVAILABLE
FRACTION DRIVES OUTFLOW, FLOWS THRU DISK
Mass Outflow
Energy 1 R
Ang.Mom. 2/1R0BInflow
0B
1
~
n
RM
Exchange: Mass
Energy
Ang. Mom.
CENTRAL
ACCRETION ENERGY
DRIVES OUTFLOW
1R
M
BREEZE MODELS
Bound, viscous inflow
Unbound, very slow outflow
Viscous stress important in outflow
Thin disk limit, a=0
Marginally bound inflowStress vanishes in outflow
No slow solution possible
WIND MODELS
Bound, viscous inflow
Unbound, dynamical outflow
Viscous stress unimportant in outflow
local) transfer mom. ang. (if
:PREDICTION
inout LL3
2~
WIND MODELS
OUTFLOW CAN BE SUBSONIC OR SUPERSONIC …
BUT REQUIRES HIGH ENERGY INPUT ()
SUBSONIC
SU
PE
RS
ON
IC
CONCLUSIONS
• A new type of ADIOS solution– “well-mixed” outflow
• Explains Ṁ~R scaling• Inflow and outflow exchange M, L, but little E• Energy to drive outflow comes from center
– Total energy supply |Eaccacc|Ṁacc~Ṁ/R
– Fraction to outflow, 1- carried outward by inflowing gas
– Details of inner accretion flow determine , • Applications: SS433, Galactic Center …