Françoise Combes Observatoire de Paris May 10, 2012 Effects of Gas Flows at Low Redshift 1

Outline 2 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

3 1- Gas accretion: essential to secular evolution Importance of gas accretion all along the evolution, to avoid too many spheroids, and replenish disks Gas accretion Secular evolution Bar-bulge cycle 1-3:1 Multiple minor 4-10:1 Major merger

Time (Myr) Bar Strength Bars formation and destruction 4 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 5  Replenish the disk, destabilises it Generate Star Formation, and bar/spiral at the same time  Gravity torques as a consequence  Gas inflow rapidly to the center inside corotation Bulge et Black hole growth In simulations, the SFR and Q-parameter adjust so that the inflow rate roughly equals the SFR Bar torques: inflow and outflow, not easy to measure (indirect)

Accretion by intermittence 6 If no continuous accretion Gas is stalled at OLR The bar remains strong (early-types)

7 Warps and polar rings from cosmic gas accretion Brook et al 2008 Model NGC 4650A Alignment through torques disk/halo, warps in the outer parts Roskar et al 2008

8 Mastropietro et al 2012 Gas accretion May mimick mergers Gas accretion may explain -- asymmetries, lopsidedness -- clumpiness -- maintained SFR

Transient Ring formation 9 Mastropietro et al 2012 The ring may disappear If the accretion continues Hoag object (HST)

2- Disk size evolution 10 Bars and spirals re-distribute angular-momentum Stars Gas SFR Age Roskar et al 2008 L LL Radial migration Sellwood & Binney 2002

Bar+spiral: radial migrations 11 Overlap of resonances Minchev et al 2010

Size evolution with redshift SF galaxies at z=1.5-3, about half the radius of local galaxies Nagy 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? 13 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 are required

Size evolution with bars/spirals 14 Minchev et al (2012) Secular evolution can triple in 3 Gyrs the effective size of disks

Thickening evolution Cororation ______ OLR While radially extending, stellar disks are thickening

Effect of in plane gas accretion 16 Minchev et al (2012)  Type II or III disks 5Mo/yr accretion rate No big effect in old stars

3- Metallicity dilution pericenter merger Gas flows due to gravity torques during an interaction  Fresh gas, low-Z in the center (also Rupke et al 2010) Amplitude 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 phase  May help to date the event 18

B Enrichment in  /Fe, speed of star formation cycles 19

Fundamental metallicity relation 20 Requires slow gas infall, chemical time-scale long wrt dynamical Mannuci et al 2010

4- Thick disk formation 21 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 22 Loebman et al 2011

5- Gas flow in cool core clusters 23 Salomé et al 2006 Perseus A, Fabian et al 2003

24 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) 25 Log Temperature (150kpc) Log density (25x50kpc) Buoyant bubbles, compression and cooling at the surfaces +Cold gas dragged upwards

OI, CII with Herschel 26 Same morphology + Same spectra between CO(2-1) and OI Same gas, cooling through different phases? No rotation, but inflows Edge et al 2010 Mittal et al 2010

6- AGN fueling Disk instabilities: Bars within bars, m=2 Lopsidedness, m=1, warps, bending But also  Clumps, turbulent viscosity, dyn. friction Feedback, outflows (SF, AGN)

28 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 Simulations of gas accretion onto a central BH  thick disks (~10pc) Zoomed simulation: cascade of m=2, m=1, + clumps and turbulence When fgas large cm -2 Clump unstable Warps, twists Bending  Thick disks  Dynamical friction of GMC If M= 10 6 Mo t~80Myr (r/100pc) 2 varies in 1/M Gas is piling up in the center: up to f=90%

Inflow rate, stochastic Hopkins & Quataert Development of a bar 2 nd resimulation1st resimulation  Episodic accretion

31 Dasyra & Combes 2011, C12.50 SFR ~ Mo/yr Outflow ~130 Mo/yr 6 out of 300 systems searched show H 2 outflows Feedback in nuclei: H2 & CO

32 Statistics -- Time-scales pc fueling  Only ~35% of negative torques in the center, scale 1"~50-100pc 6 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 10 7 yrs, due to feedback? Rare to see binary AGN, not fueled at the same time Difficult to identify the driver: bars have weaken then  Star formation fueled by the torques, always associated to AGN activity, but longer time-scales

35% showing gas accretion 33  Galaxies with embedded bars, or bars/ovals The inner structure takes over the negative torque of the bar beyond the ILR  Galaxies with no ILR, and only one primary bar (case of NGC 3627)

65% showing no central gas accretion 34  Galaxies with embedded bars, or bars/ovals But the gas is still stalled at an ILR ring (cf N6951, N4321..)  Galaxies with no contrasted feature towards the center Almost axisymmetric, without torques (case of NGC 7217, N5953..)

CONCLUSION 35  Importance of gas accretion in secular evolution to replenish disks  Size of disks: non-axisymmetries redistribute matter Exponential 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