Radiation Pressure Supported Starburst Disks & AGN Fueling
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Transcript of Radiation Pressure Supported Starburst Disks & AGN Fueling
Radiation Pressure Supported Starburst Disks & AGN Fueling
Todd ThompsonUC Berkeley
With Eliot Quataert & Norm Murray
Evidence for Feedback: Winds
M82 (Subaru)
NGC 1569 (HST)
Regulation of star formation
on galactic scales.
Interactions, Mergers Star Formation
NGC 4038/4039 (HST)
ULIRGs
Borne et al. (2000)
Disk-like kinematics
Star formation ~102-3 M/yr
<n>~103-4
cm-3
~100 pc scales
The Standard Lore:Energy Deposition by Supernovae
Strickland & Stevens (2000)
Collective effects of supernovae regulate the ISM and drive a hot thermal wind.
McKee & Ostriker (1977)Chevalier & Clegg (1985)de Young & Heckman (1994)
Efficiency may be very low in the high-density ISM of starburst galaxies.
A New Model: Radiation Pressure• Starburst or AGN photons are absorbed and scattered
by dust grains (UV~100-1000 cm2 g-1).
• Dust is collisionally coupled to gas:• Efficient feedback mechanism: couples to cold and
dusty component, most of the mass.• Large-scale winds: Starbursts are near their
“Eddington” limit (Murray, Quataert, Thompson 2005)
• In ULIRGs, the ISM is optically thick to re-radiated IR on ~100 pc scales - radiative diffusion.
€
λ ≈10pc a0.1ρ 3n1−1
€
( ˙ M W / ˙ M *) ~ (10−3c /2σ ) ~ 1
Starburst Disks• Marginal stability, self-regulation: Toomre Q~1.
• Vertical hydrostatic equilibrium:
• Star formation:
• Radiative diffusion:
• Accretion ( or m):
• Modified Schmidt Law:
€
Q =κ Ωcs
πGΣg
~Ω2
2πGρ⇒ ρ ~
Ω2
2πGQ
€
F = σ SBTeff4 = (1/2)ε ˙ Σ *c
2
€
p ≈ ρh2Ω2 ∝ Σg2
€
T 4 ≈τ IRTeff4 ∝κΣg
˙ Σ *
Sirko & Goodman (2003) Thompson, Quataert, & Murray (2005)
€
˙ Σ * ∝ Σg2 /τ IR ∝ Σg /κ
€
˙ M (r) = ˙ M out − 2π rRout
r
∫ ˙ Σ * dr
TheRosseland Mean Opacity
Dust sublimates! Tsub ~ 1000 K
At Rout, if
then all of the gas is consumed in star formation on the scale Rout.
Equivalently,
Bifurcation: Starburst vs. AGN
€
˙ M (r)€
˙ M *(r)
€
τAdv > τ *
€
˙ M out < ˙ M crit
Bifurcation: Starburst vs. AGN
At Rout, if
then the gas can propagate to small radii. It passes through the ``opacity gap’’ and fuels a bright central AGN.
€
τAdv < τ *
€
˙ M out > ˙ M crit
Bifurcation: Starburst vs. AGN
Bifurcation: Starburst vs. AGN
Very strong
in the opacity gap yields vertical structure withh/r~1.
Origin of nuclear obscuration in some AGN? Winds? NLR?
€
dκ /dz
Bifurcation: Starburst vs. AGN
AGNReprocessing?
The Galactic Center: A Nuclear Starburst?
The opacity gap generates a sharp peak in the star formation rate at ~0.1 pc for our galactic center.
Levin & Beloborodov (2003)Genzel et al. (2003)
Summary• Radiation pressure
– can dominate feedback in the optically thick regions of starbursts.– couples to the cold dusty component, most of the mass.– can support the marginally-stable starburst disk.
• Disk models (given , or m, Rout, MBH, fg)– predict starburst structure:– are in good agreement with observations (local & high-z ULIRGs).– fuel bright AGN without violating observational limits.– predict strong bifurcation between starburst dominated
& AGN dominated solutions.– predict a nuclear starburst on ~1 pc scales (opacity gap).– predict qualitative change in the Schmidt Law:
• Radiation pressure can drive large-scale mass-loaded winds: sets Faber-Jackson, M-, & maximum L of galaxies & BHs.
Thompson, Quataert, Murray (2005) Murray, Quataert, & Thompson (2005)
€
T(r), Teff (r), F(r), η (r), ρ(r), ˙ Σ *(r), cs(r)
€
˙ Σ * ∝ Σg2 /τ IR ∝ Σg /κ
The End