Feedback from Momentum-Driven Winds
Eliot Quataert (UC Berkeley)
w/ Norm Murray & Todd Thompson
NGC 3079 w/ HST
Outline
• Context: Thermally-Driven Galactic Winds (supernovae)
• Momentum-Driven Galactic Winds (radiation pressure)
– Three Eddington Limits
– Cosmological Speculation: Self-regulated Starbursts and BH Growth
The Standard Lore: Supernovae Driven Galactic Winds
Strickland & Stevens (2000)
Hot gas blown out by collective effects of SN
efficiency uncertainbecause most of SN
energy deposited in ISMmay be radiated away
simulations suggest that little mass is blownaway because SN
vent their energy by‘blowing out’ of the
galactic plane
Interaction of Cold Gas & Hot Wind
Poludnenko et al. 2002
Cold Clouds destroyed by hot wind
Results probably underestimate destruction of cold gas
(e.g., no evaporation)
unclear how to account foroutflowing cold gas seen
in absorption in LBGs, ULIRGs,local starbursts, etc.
Radiation Pressure Driven Winds
• Dust absorbs the radiation produced by starbursts or AGN
• Dust collisionally coupled to the gas: mfp ~ 10 a0.1n1 pc
• Momentum-driven wind:
• Efficient mechanism for blowing cold dusty gas out of a galaxy (i.e, couples to the phase of the ISM with most of the mass)
The Eddington Limit(s)
• To blow gas out of galaxy, luminosity must exceed LEDD
• Optically Thick Clouds of Gas: Mass Mc
Area Ac
Frad
classicoptically thin LEDD
Mc/Ac ~ cRc ~ mpNH
22 = GM(r)/r ~ const
Absorption-line Probes of Outflowing Cold Gas in Local Starbursts
Data from Heckman et al. (2000)
Eddington Limit
Terminal Velocity of Outflowing Cold Gas
Data from Martin (2004)
V term ~ 2.5 ~ V esc
ULIRGs
LIRGs
Dwarfs
Hot gas inferred tohave Vhot ~ 500 km/s
independent of
Ram pressure in hot windVterm ~ Vhot ~ 500 km/s
L ~ LEDD Vterm ~
Terminal Velocity of Outflowing Cold Gas
Data from Martin (2004)
V term ~ 2.5 ~ V esc
ULIRGs
LIRGs
Dwarfs
interesting implicationsfor enriching IGM,Ly- forest, etc.
small galaxiesmay preferentially
lose more of their mass
The Optically Thick ‘Shell’ Limit(Galaxy Opaque Along Most Lines of Sight)
M(r) = 22r/G Mg = fM
For L > LM
momentum injection is sufficient to blow away all of the gas in a galaxy
Conjecture: LM is an upper limit to the luminosity of a starburst or AGN: systems that reach LM
self-regulate & L does not increase further
The Maximum Luminosity of Starbursts
Decay of Starbursts
Based on Models of Bruzual & Charlot (2003)
The Origin of the Faber-Jackson Relation?
L LM 4
in high zstarburstssuch as
LBGs, Scubasources, …
(probably in mergers)
L LFJ asstarburst fades
Black Holes
• Efficient angular momentum transport in mergers
can trigger BH growth and AGN activity
• Dust present outside Rsub ~ 1 L46 pc
• If L LM, AGN can blow dusty gas out of
its vicinity, controlling its own fuel supply
1/2
Josh Barnes
The Maximum Luminosity of Quasars
from width of OIII line in NLR
The Origin of the M- Relation?
• Inside Rsub ~ 1 L46 pc, dust destroyed
• ‘Normal’ optically thin Eddington limit applies
• With sufficient fuel supply, L ~ LEDD MBH
• As BH grows, L LM 4
1/2
Summary• Radiation Pressure can drive powerful galactic winds and is an
important feedback mechanism in the growth of galaxies & BHs
• Can account for properties of cold outflowing gas seen in starbursts
• Vterm ~ may modify picture of metal enrichment and impact of galactic winds on Ly- forest (winds less destructive …)
• LM ~ 3x1046 200 ergs/s: maximum luminosity of Galaxies & BHs?
– may regulate mass of *s in early type galaxies (FJ) & mass of their central BHs (MBH-)
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