Post on 12-Jan-2016
description
Stellar & AGN Feedback in Galaxies
GLCW8 Columbus 2007
Evidence for Feedback(Self-limited Star Formation?)
Mb~3
M*~4
Krabbe et al
astro-ph/0703804
Inefficient Star Formation-Feedback?
Kennicutt 1998
Ý *; 0.017
Implies same physics over 4 decades in gas
Evidence for Feedback: Winds-significant mass & momentum in cold gas
M82 (Subaru)
e.g., Heckman et al. 00; Martin 04,05
Evidence for Feedback(self-limiting BH accretion?)
Greene & Ho 05
Large-Scale Feedback
Fabian et al (2006)
Perseus Cluster
Fabian et al (2006)
Perseus Cluster
Large-Scale Feedback
Feedback Mechanisms• Energy Input
– Stars (local)• SN• HII• Winds
– AGN • Via Radiation• Jets (large scale)• Winds (Broad Absorption Line QSOs)
• Momentum Input– Stars
• SN• Radiation
– AGN• Radiation
Radiation Pressure Feedback • Dust absorbs the radiation produced by starbursts or AGN
• Dust collisionally coupled to the gas: mfp ~ 1 a0.1n1 pc
• Starlight provides turbulent pressure support of ISM • Momentum-driven wind: V∞ ~ Vc L/c MWV∞
L ~ 10-3 M*c2 ~ MWV∞c MW ~ M*
• 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)
·
· · · ·
Terminal Velocity of Outflowing Cold Gas
Data from Martin (2005)
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 ~
The Maximum Luminosity of Starbursts
Black Holes• Efficient angular momentum transport in mergers
can trigger BH growth and AGN activity
• Dust present outside Rsub ~ 1 L1/246 pc
• If L LM, AGN can blow dusty gas out of
its vicinity, controlling its own fuel supply
1/2
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
LEDD ~ LM when MBH ~ 108M f0.1 2004
Is the BH or Stellar Feedback Responsible for the Bulk of the Gas
Removal?
• L*=4fg4c/G seen; implies radiation limited (not BH limited) star formation rate
• Winds are seen; if massive enough, Faber-Jackson follows. Not blown by AGN
• BH is affected by but not fg; fine tuning required to arrange for Faber-Jackson
• See ongoing star formation in ellipticals (at low level)--no supression of star formation in situ
• But AGN feedback likely restricts mass accretion from large radii
Feedback in Galactic Disks
• Marginally Stable:
• H/R~vT/vc roughly constant
• Stars form in molecular gas
• dN/dM~ M-1.8 => mass in big clouds
• Most stars form in Giant Molecuar Clouds
Qvc vTGr
1
Clumps and Star Clusters
• IRDCs: dN/dM~M-1.97 (Simon et al. ApJ 2006)
• Clumps: dN/dM~M-1.8
• Molecular Cloud Cores dN/dM~-1.7 (Lada,Bally
& Stark 1991)
• Clusters: dN/dM~M-2 (Lada & Lada 2003)
• => Most stars form in massive clusters
Carina
• Mass GMC ~ 5x105 Solar masses
• Radius GMC ~ 40pc
• L=2.5x107 Lsun (~1041 erg/s)
– 70% from Trumpler 16, 16% from Tr 14
– Rcl ~ 2pc
• X-rays consistent with standard IMF
Clumps in Carina
Forces Acting In Carina• Inward
– Self-Gravity of shell -GMsh(R) Msh(R)/R2
– Turbulent pressure 4r2 vT2
– Ram pressure 4r2 vsh2
• Outward– HII gas pressure
• 4r2 nkT = 4r2 (3Q/4r3)1/2 kT
– Radiation pressure (1+)L/c, <1
– Jet ram pressure dM/dt vjet
Dynamical Model (1D)
Dynamical Model (1D)
Dynamical Model (1D)
Dynamical Model (1D)
Dynamical Model (1D)
Summary(Local Feedback)
• Star formation is observed to be inefficient• Scaling relations imply a single mechanism• SN too late to halt SF in Starbursts/ULIRGS• HII helps in MW, not in ULIRGS• Stellar Winds seem ineffective• Radiation pressure on dust can work