MUSE & ALMA Françoise Combes Observatoire de Paris Toulouse, 19 March 2009.
Françoise Combes Observatoire de Paris May 10, 2012
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Transcript of Françoise Combes Observatoire de Paris May 10, 2012
Françoise CombesObservatoire de ParisMay 10, 2012
Effects of Gas Flows at Low Redshift
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Outline
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1- Gas accretion and secular evolution: bars
2- Evolution of disk size, radial migration, inflow/outflow
3- Dilution of metallicity
4- Thick disks
5- Cooling flows: inflow/outflow again
6- AGN fueling
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1- Gas accretion: essential to secular evolution
Importance of gas accretion all along the evolution, to avoidtoo many spheroids, and replenish disks
Gas accretionSecularevolution
Bar-bulge cycle
1-3:1
Multiple minor
4-10:1
Major merger
Time (Myr)
Bar
Str
engt
h
Bars formation anddestruction
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Self-regulated cycle:Bar produces gas inflow, and Gas inflow destroys the bar
2% of gas infall is enough to transform a bar in a lens(Friedli 1994, Berentzen et al 1998, Bournaud & Combes 02, 04)
Effect of gas inflow
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Replenish the disk, destabilises itGenerate Star Formation, and bar/spiral at the same timeGravity torques as a consequenceGas inflow rapidly to the center inside corotationBulge et Black hole growth
In simulations, the SFR and Q-parameter adjust so that theinflow rate roughly equals the SFR
Bar torques: inflow and outflow, not easy to measure (indirect)
Accretion by intermittence
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If no continuous accretionGas is stalled at OLRThe bar remains strong(early-types)
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Warps and polar rings from cosmic gas accretion
Brook et al 2008
Model NGC 4650AAlignment through torques disk/halo, warps in the outer parts
Roskar et al 2008
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Mastropietro et al 2012
Gas accretion
May mimickmergers
Gas accretion may explain -- asymmetries, lopsidedness-- clumpiness-- maintained SFR
Transient Ring formation
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The ring may disappearIf the accretion continues
Hoag object (HST)
2- Disk size evolution
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Bars and spirals re-distribute angular-momentum Stars
Gas
SFR
Age
Roskar et al 2008
L
L
Radial migrationSellwood & Binney 2002
Bar+spiral: radial migrations
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Overlap of resonances
Minchev et al 2010
Size evolution with redshift
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102 SF galaxies at z=1.5-3 , about half the radius of local galaxiesNagy et al 2011, z=2-3 Weinzirl et al 2011
re ~(1+z)-
=1.4 Nagy et al 2011=1.3 van Dokkum et al 2010=1.1 Mosleh et al 2011
Stellar radii at a given mass are ~half lower, at z=2-3
Minor mergers to increase galaxy radius?
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Newman et al 2011
Candels: search for companions around quiescent red galaxies ~15%
Possible if e < 1Gyr (e merging time)
But possible only for z=1,At z=2 other processes arerequired
Size evolution with bars/spirals
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Minchev et al (2012)
Secular evolution can triple in 3 Gyrs the effective size of disks
Thickening evolution
15---- Cororation ______ OLR
While radially extending, stellar disks are thickening
Effect of in plane gas accretion
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Minchev et al (2012)
Type II or III disks
5Mo/yr accretion rate
No big effect in old stars
3- Metallicity dilution
pericentermerger
Gas flows due to gravity torques during an interactionFresh gas, low-Z in the center (also Rupke et al 2010)
Amplitude 0.2-0.3 dex in agreement with observations(Kewley et al. 2006, Rupke et al. 2008) 17
Dilution due to flybys
Dilution seen in fly-bys also, Montuori et al 2010
Duration < 500 Myr elements enrichment during this phaseMay help to date the event
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B
Enrichment in /Fe, speed of star formation cycles19
Fundamental metallicity relation
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Requires slow gas infall, chemical time-scale long wrt dynamicalMannuci et al 2010
4- Thick disk formation
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Several scenarios at play:In addition to accretion and disruption of satellites, or disk heating due to minor merger
Radial migration, via resonant scattering
Loebman et al 2011
Radial migration: abundances & Vrot
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5- Gas flow in coolcore clusters
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Salomé et al 2006
Perseus A , Fabian et al 2003
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Cold CO in filaments
Salome et al 2008
Velocity much lower than free-fall
Here also, inflow and outflow coexist
The molecular gas coming from previous cooling is dragged out by the AGN feedback
The bubbles create inhomogeneities and further cooling
The cooled gas fuels the AGN
Numerical simulations (Revaz, Combes, Salome 2007)
25Log Temperature (150kpc) Log density (25x50kpc)
Buoyant bubbles, compressionand cooling at the surfaces+Cold gas dragged upwards
OI, CII with Herschel
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Same morphology +Same spectrabetween CO(2-1) and OI
Same gas, cooling throughdifferent phases?
No rotation, but inflows
Edge et al 2010Mittal et al 2010
6- AGN fueling Disk instabilities: Bars within bars, m=2 Lopsidedness, m=1, warps, bending
But alsoClumps, turbulent viscosity, dyn. friction
Feedback, outflows (SF, AGN)
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Bar gravity torques
Torque map for NGC 3627 (Casasola et al 2011)
Action on the gas: sign of the torques, depending on the phase shift between gas and stellar potential
Torques computed from the red image, on the gas distribution
The gas transfers AM to the stars Weakens or destroys the bar
Small-scale accretion
Hopkins et al 2011
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Simulations of gas accretion onto a central BH thick disks (~10pc)Zoomed simulation: cascade of m=2, m=1, + clumps and turbulence
When fgas large1022-1025 cm-2
Clump unstableWarps, twistsBendingThick disks
Dynamicalfriction of GMCIf M= 106Mot~80Myr (r/100pc)2
varies in 1/M
Gas is piling up in the center: up to f=90%
Inflow rate, stochastic
Hopkins & Quataert 2010
30Development of a bar
2nd resimulation 1st resimulation
Episodic accretion
31Dasyra & Combes 2011, 2012
4C12.50 SFR ~400-1000 Mo/yrOutflow ~130 Mo/yr
6 out of 300systems searchedshow H2 outflows
Feedback in nuclei: H2 & CO
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Statistics -- Time-scales10-100pc fueling
Only ~35% of negative torques in the center, scale 1"~50-100pc6 out of 16 galaxies (NUGA sample, cf Garcia-Burillo et al)N1961, N2782, N3147, N3368, N3627, N3718, N4321, N4569,N4579, N4736, N4826, N5248, N5953, N6574, N6951, N7217
Rest of the times, positive torques, maintain the gas in a ring
Short fueling phases, a few 107 yrs, due to feedback?Rare to see binary AGN, not fueled at the same timeDifficult to identify the driver: bars have weaken then
Star formation fueled by the torques, always associated to AGNactivity, but longer time-scales
35% showing gas accretion
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Galaxies with embedded bars, or bars/ovalsThe inner structure takes over the negative torque of the barbeyond the ILR
Galaxies with no ILR, and only one primary bar(case of NGC 3627)
65% showing no central gas accretion
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Galaxies with embedded bars, or bars/ovalsBut the gas is still stalled at an ILR ring (cf N6951, N4321..)
Galaxies with no contrasted feature towards the centerAlmost axisymmetric, without torques(case of NGC 7217, N5953..)
CONCLUSION
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Importance of gas accretion in secular evolution to replenish disks
Size of disks: non-axisymmetries redistribute matterExponential disks + radial migration, disks can triple in size
Metallicity dilution due to gas accretion, together with interactions
Warps and polar rings, when non-aligned accretion
Thick disk formation: mergers, or secular evolution?
Gas accretion in cool core clusters: inflow/outflow bubbling
Fueling of AGN: intermittent, triggered by non-axisymmetries