1 / 35

Françoise Combes Observatoire de Paris May 10, 2012

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

zaina
Download Presentation

Françoise Combes Observatoire de Paris May 10, 2012

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

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

  4. Bar Strength Time (Myr) Bars formation anddestruction 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)

  5. Effect of gas inflow • 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)

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

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

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

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

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

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

  12. Size evolution with redshift 102 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 Stellar radii at a given mass are ~half lower, at z=2-3 re ~(1+z)-a a=1.4 Nagy et al 2011 a=1.3 van Dokkum et al 2010 a=1.1 Mosleh et al 2011

  13. Minor mergers to increase galaxy radius? Candels: search for companions around quiescent red galaxies ~15% Possible if te < 1Gyr (te merging time) But possible only for z=1, At z=2 other processes are required Newman et al 2011

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

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

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

  17. 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 0.2-0.3 dex in agreement with observations • (Kewley et al. 2006, Rupke et al. 2008)

  18. 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

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

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

  21. 4- Thick disk formation 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

  22. Radial migration: abundances & Vrot Loebman et al 2011

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

  24. Cold CO in filaments 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 Velocity much lower than free-fall Salome et al 2008

  25. Numerical simulations(Revaz, Combes, Salome 2007) Buoyant bubbles, compression and cooling at the surfaces +Cold gas dragged upwards Log Temperature (150kpc) Log density (25x50kpc)

  26. OI, CII with Herschel 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

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

  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

  29. Small-scale accretion 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 • 1022-1025 cm-2 • Clump unstable • Warps, twists • Bending • Thick disks • Dynamical • friction of GMC • If M= 106Mo • t~80Myr (r/100pc)2 • varies in 1/M Gas is piling up in the center: up to f=90% Hopkins et al 2011

  30. 2nd resimulation 1st resimulation Inflow rate, stochastic Episodic accretion Development of a bar Hopkins & Quataert 2010

  31. Feedback in nuclei: H2 & CO 6 out of 300 systems searched show H2 outflows 4C12.50 SFR ~400-1000 Mo/yr Outflow ~130 Mo/yr Dasyra & Combes 2011, 2012

  32. Statistics -- Time-scales10-100pc 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 107 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

  33. 35% showing gas accretion • 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)

  34. 65% showing no central gas accretion • 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..)

  35. CONCLUSION • Importance of gasaccretion in secularevolution to replenishdisks •  Size of disks: non-axisymmetriesredistributematter • Exponentialdisks + radial migration, diskscan triple in size •  Metallicity dilution due to gasaccretion, togetherwith interactions •  Warps and polar rings, whennon-alignedaccretion • Thickdisk formation: mergers, or secularevolution? • Gasaccretion in cool core clusters: inflow/outflowbubbling • Fueling of AGN: intermittent, triggered by non-axisymmetries

More Related