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How to Feed AGN The NUGA survey view. Santiago GARCIA-BURILLO Observatorio Astronómico Nacional (OAN)-Spain. The NUGA team S García-Burillo(1), F.Combes(2), A.Eckart(3), L.Tacconi(4), L.Hunt(5), S.Leon(6), A.Baker(4), P.Englmaier(7), F.Boone(8), E.Schinnerer(9), R.Neri(10), M.Krips(3).

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How to Feed AGN The NUGA survey view


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    1. How to Feed AGNThe NUGA survey view Santiago GARCIA-BURILLO Observatorio Astronómico Nacional (OAN)-Spain The NUGA team S García-Burillo(1), F.Combes(2), A.Eckart(3), L.Tacconi(4), L.Hunt(5), S.Leon(6), A.Baker(4), P.Englmaier(7), F.Boone(8), E.Schinnerer(9), R.Neri(10), M.Krips(3). (1)-OAN, Spain (2)-LERMA, France (3)-Universitaet zu Koeln, Germany (4)-MPE, Germany (5)-CAISMI, Italy (6)-IAA, Spain (7)-Universitaet Basel, Switzerland (8)-Bochum University,Germany (9)-NRAO, USA , (10)-IRAM, France The Evolution of Starbursts, August 16-20, 2004, Bad Honef, Germany

    2. FUELING AGN in SEYFERTS and LINERS Where do we stand...? ->AGN fuelled with material originally away from gravitational field of BH: problem of angular momentum removal. ->Weak correlation between 1kpc-scale perturbations and activity in ‘Local Universe’ AGN: Seyferts and LINERs. -> Critical scale for AGN feeding: <100pc. AGN duty cycle is short! -> Search for correlation with `secondary instabilities’ from 1 kpc to <100 pc: nuclear bars? spiral gas waves?, nuclear-warps? m=1 modes? ... No consensus on the driving mechanism!...(only one? several? ‘none’?...) ->Is the ‘inner playground’ (r<1 kpc) of low-L AGN different from non-active galaxies? ( Combes 2000-2004; Wada et al 2000-2004; Englmaier & Shlosman 2000; Shlosman 2001; Maciejewski et al 2002, 2004; Knapen 2001, 2004; Jogee 2004; Laine et al 2002; Garcia-Burillo et al 2000, Schinnerer et al 2000.......and many others!)

    3. NUclei of GAlaxies: the NUGA project NUGA: a CO survey of low-L AGN with IRAM Bure Interferometer -> CO: best tracer of distribution and kinematics of molecular gas in nuclei. -> High spatial resolution (0.5’’-1”) paramount to reach ‘critical’ scales: <50-100pc. ->NUGA: first interferometric CO survey of a significant sample of AGN.->NUGA core sample:12 spirals ranging from Seyferts 1-2 to Liners. NUGA aims at compiling sample of 25-30 galaxies by including PdBI data available from consortium members. Strategy for NUGA : ->Multiwavelength approach:beyond CO maps-->NIR HST , VLA HI and VLBI radio images.->Derivation of gravitational torques on the gas: efficiency of AGN feeding.->Numerical simulations of the gas dynamics compared with observations. Evolution of instabilities. ->Twofold exploitation of NUGA data: ----1/Detailed case-by-case studies:NGC4826 (García-Burillo et al 2003, A&A,407), NGC7217(Combes et al 2004, A&A, 414), NGC1961 (Baker et al 2004 in prep), NGC3718(Krips et al 2004) ----2/Global exploitation of sample upon completion (06/04)

    4. CO images of NUGA LINER T/LINER HII/T LINER/SEYF. 1 SEYF. 1 SEYF. 2 T/LINER SEYF. 2 SEYF. 2 LINER SEYF. 2 T/SEYF. 2

    5. NUGA reveals m=1 instabilities • The new 0.5’’-0.7’’ maps reveal m=1 perturbations appearing as one-arm spirals and lopsided disks in several galaxies. Perturbations appear at various scales, from several tenstoseveral hundreds of pc. T/LINER NGC4826 LINER NGC1961 AGN AGN  20pc 500pc 0’’.6 (=12pc) CO(2-1) map of NGC4826 shows molecular gas distribution lopsided near AGN. 0’’.7 (=180pc) CO(2-1) map of NGC1961 shows strong one arm spiral response (Garcia-Burillo et al 2003, A&A, 407; and 2004 in prep) ( Baker et al 2004, in prep)

    6. Searching for observational evidences of ‘ongoing’ feeding... I/ TRANSITION objects:NGC4826 (Garcia-Burillo et al 2003, A&A, 407; and 2004 in prep) ->NGC4826is atransition object hosting 2 counter-rotating gas disks. Molecular gas disk corotates with stars. -> NUGA maps show two m=1 spirals (Arms I-II; r>100pc) and a lopsided nuclear disk at r<80-100pc -> Analysis of observed streaming motions suggests inner instabilities are ‘fast’ trailing m=1 perturbations......Inner instabilities would not drive AGN fueling!. ->Kinematical signature of lopsided nuclear disk along minor axis suggestive of outflowrather than inflow near AGN. 40pc CO(2-1)(contours)-on B-I/HST(colours) CO(2-1) p-v diagram along minor axis Conclusion.... ->Large molecular gas concentration at radii ~ 80-100pc from the AGN (0.5x108Msun), but negative evidence of inflow from gas kinematics.

    7. Searching for observational evidences of ‘ongoing’ feeding... II/ LINERS:NGC4579 (Garcia-Burillo et al 2004 in prep) ->NGC4579: S 1.9/L1.9 barred spiral. Prototype of low-L AGN.->Molecular gas distribution in inner 500pc mimics gas response to bar potential: gas piles up in 2 leading spiral arcs: x1 orbits crowding However m=2 point-symmetry breaks up in the inner 100pc disk: lopsidedness takes over!. AGN in off-centered 150pc gas disk with shell-like features seen in HST V-I and PdBI CO(2-1) maps CO(2-1)(contours)-on V-I/HST(colours) CO(2-1) p-v diagram along major axis Kinematical signature of highly non-circular motions for gas on major axis p-v plot near AGN (<100pc) AGN 70pc Conclusion.... -> Molecular gas kinematics in the inner 100pc disk (~105Msun )suggestive of expanding motions? highly elliptical/non coplanar orbits?...AGN feeding issue still unclear ! (modelling in progress...)

    8. Searching for observational evidences of ‘ongoing’ feeding... III/ SEYFERTS:NGC6951 (Schinnerer et al 2004 in prep) -> NGC6951: barred spiral prototype of Seyfert 2.->Molecular gas distribution inside 700pc suggests gas along x2 orbits in bar potential: gas piles up in highly contrasted nuclear spiral arms (~4x108 Msun) feeding starburst while little molecular gas 200 pc from the AGN. CO(2-1)-un weight on J-H/HST(colour) CO(2-1)-na weight on J-H Conclusion.... -> CO(2-1) central clump on the AGN of ~106Msun betrays feeding in the past.-> NW gas extension of ~107Msun linked to filamentary dusty spiral in J-H HST map istantalazing evidence of ongoing feeding 200pc CO(2-1) Major Axis p-v plots

    9. Evaluation of Gravitational Torques on the Gas ->Gravitational torques of the stellar potential on the gas can be derived if fair representations of both are available. -> We use NIR HST images to get the potentials and the high-resolution CO maps from NUGA to get the gas distribution in our sample. ->Efficiency of torques will depend on the strength of non-axisymmetric perturbations but also on the existence of phase shifts between the gas and the stars distributions. I Deriving potentials ...

    10. Evaluation of Gravitational Torques on the Gas II Deriving torques ... III Getting the efficiencies...

    11. Gravitational Torques in NGC4826 I/ TRANSITION objects (Garcia-Burillo, Combes, Schinnerer et al 2004 in prep) The stellar potential and gas distribution in the inner 500pc playground... CO(2-1)(contours)-on H band HST(colours) deprojected Fourier decomposition of stellar potential: Q_i, Phi_i 40pc ->Strength of non-axisymmetric stellar potential, measured by QT , is low for 500pc>r>50pc.->Larger values of QT for r<50pc are due to small oval perturbation

    12. Gravitational Torques in NGC4826 I/ TRANSITION objects (Garcia-Burillo, Combes, Schinnerer et al 2004 in prep) ->Torques map reproduces butterfly-like pattern driven by the stellar oval for r<100pc, roughly oriented N/S. Torques Map 40pc ->Efficiency of stellar torques to drive angular momentum loss in gas is low at all radii: low + oscillating values of dL/L. Average value slightly>0!-> This is compatible with scenario inferred from CO observations: while gas concentration is large at r<100pc , dynamical evidence of inflow in this transition object is scarce.--->Stellar perturbations have virtually no role in AGN feeding at present Efficiency of Torques

    13. Gravitational Torques in NGC4579 II/LINERS (Garcia-Burillo, Combes, Schinnerer et al 2004 in prep) The stellar potential and gas distribution in the inner 500pc playground... CO(2-1)(contours)-on I band HST(colours) deprojected Fourier decomposition of stellar potential: Q_i, Phi_i 150pc ->Stellar potential strength, measured by QT , is driven by the stellar bar identified in the image.->Large values of QT for r<200pc are measured.

    14. Gravitational Torques in NGC4579 II/LINERS (Garcia-Burillo, Combes, Schinnerer et al 2004 in prep) ->Torques map reproduces butterfly-like pattern driven by the large scale stellar bar. Change of sign and orientation of quadrants fit the theoretical expectations. Torques Map 150pc ->Efficiency of stellar torques is ~5 times larger in NGC4579 than in NGC4826: dL/L<0 over 800pc down to r=200pc. ->Stellar torques become positive for r<200pc , however! !--->Stellar perturbations have virtually no role in AGN feeding at present. Efficiency of Torques

    15. Gravitational Torques in NGC6951 III/SEYFERTS (Garcia-Burillo, Combes, Schinnerer et al 2004 in prep) The stellar potential and gas distribution in the inner 500pc playground... Fourier decomposition of stellar potential: Q_i, Phi_i CO(2-1)(contours)-on H band HST(colours) deprojected 200pc ->Large-scale NIR images of NGC6951 reveal a stellar bar on kpc scales. However, QTis here driven by a nuclear bar/oval identified in the image at r<500pc.->Low values of QT are measured for the nuclear bar.

    16. Gravitational Torques in NGC6951 III/SEYFERTS (Garcia-Burillo, Combes, Schinnerer et al 2004 in prep) ->Torques map reproduces butterfly-like pattern driven by the nuclear bar. Torques Map ->Efficiency of stellar torques to get rid of Lgas is ~3-5 times larger in NGC6951 than in NGC4826: dL/L<0 over 800pc down to r=300pc. ->Average stellar torques become very low and marginally positive for r<300pc, however!--->Stellar perturbations have virtually no role in AGN feeding at present. Efficiency of Torques

    17. Summary • NUGA maps show wide range of instabilities at r~10-500 pc from AGN. This includes all types of m=2 and m=1-like perturbations . • NUGA maps unveil a lot of m=1 instabilities in AGN.----->The role of m=1 modes in fuelling still controversial: see, for example, NGC4826 • Perturbations seen in NUGA maps can be either self-gravitating (low Q) or non self-gravitating (high Q). • Analysis of stellar gravity torques on nuclear gas disks of NGC4826(T), NGC4579(LINER) and NGC6951(Seyfert) allowed us to probe the T/LINER/Seyfert sequence and search for a trend in AGN feeding history.---> AGN feeding process may happen in two steps: stellar torques help at feeding nuclear SB ‘first’ on 100pc scales, and a second transitory mechanism is swichted on for ´a while’ in a second step (gaseous?(=viscosity?), stellar?(=short-lived nuclear bar?))

    18. Caught in the act: a nuclear bar feeding M100 AGN? POSITIVE TORQUES NEGATIVE TORQUES POSITIVE TORQUES NEGATIVE TORQUES

    19. The NUGA supersample -> Global exploitation of NUGANUGA aims at compiling sample of 25-30 galaxies by including PdBI data available from consortium members. Availability of non active galaxies crucial to build up comparison sample.

    20. Searching for AGN ‘feedback’ on molecular gas... Usero, García-Burillo, Fuente et al. 2004, A&A, 419 NGC1068: Seyfert 2 CO(1-0) (PdBI;Schinnerer et al. 00) • Molecular survey (9 species) provides new constraints to the chemistry of the Circumnuclear Disk (CND) in NGC1068. Molecular Gas Inventory of the CND of NGC1068 • X-ray driven chemistry models explain abundance ratios measured in the CND

    21. ...and m=2 instabilities Self-Gravitating NGC7217 (Combes et al 2004, A&A, 414) ->LINER with high degree of axisymmetry. Halo+bulge dominant. It has 3 stellar rings but paradoxically no strong bar! ->NUGA 1-0 map shows molecular gas in circular ring (m=0) covering nuclear dust ring and multi-arm spiral pattern identified by HST. ->Little gas near AGN source. Nuclear spot seen in 2-1 and 1-0 of < 106 solar masses. Associated with stochastic mini spiral seen by HST. ->Inner boundary of molecular ring is very sharp!:... . Evidence that AGN fueling is negligible inside the ring at present! 12CO(1-0) (top) and 12CO(2-1) (bottom) maps overlaid with HST V-I image Non Self-Gravitating 

    22. LINERS Rings and spirals in NGC7217(Combes et al 2004, A&A,414 ) Numerical simulations ->The N7217 paradox: 3 contrasted rings but no bar at present! ->N-body simulations including stars+gas self-gravity and star formation explore two extreme models to account for `present’ morphology: --1/Run A: mild persistent oval. --2/Run B: strong bar dissolved after gas infall -> Mild oval model is favoured. Nuclear gas ring formed near ILR of oval distortion. Gas piles up on the inner side of the ring:... ....no significant AGN feeding at present ! Run A Run B

    23. Transition m=1 instabilities in NGC4826(Garcia-Burillo et al 2003, A&A, 407) NGC4826 ->Transition object hosting 2 counter-rotating gas disks. Molecular gas disk corotates with stars. ->NUGA maps show two m=1 spirals (Arms I-II; r>100pc) and a lopsided nuclear disk at r<40-50pc ->Analysis of observed streaming motions suggests inner instabili-ties are ‘fast’ trailing m=1 pertur-bations... Inner instabilities would not drive AGN fueling!. Expected pattern of velocity perturbations due to m=1 spirals (slow/fast) according to DW linear models. For fast ‘modes’ m=1 develops mostly outside corotation. Isovelocity maps in N4826

    24. T/LINERS m=1 instabilities in NGC4826(Garcia-Burillo et al 2003, A&A, 407) Q maps in NGC4826: Gas self-gravity -> Stellar perturbations seem inefficient to drive angular momentum transfer. -> While stellar potential inefficient, is gas self-gravity potentially important? • -> Estimate of Toomre Q parameter for the gas disk: • CO-->Ngas and Qgas: • 1/Arm I-II have very low Q ( close to 1) • 2/Lopsided instability in nuclear disk may have Q<2-3 • ->Gas self-gravity of observed instabilities might favour/inhibit AGN feeding? • --->to be explored in numerical simulations

    25. Seyferts m=1, 2 instabilities in NGC4579(García-Burillo et al 2004, A&A, in prep ) ->NGC4579: S1.9/L1.9 barred spiral. Prototype of low-L AGN.-> Molecular gas distribution in inner 500pc mimics gas response to bar potential: gas piles up in 2 leading spiral arcs: x1 orbits crowding However m=2 point-symmetry breaks up in the inner 100pc disk: lopsidedness takes over!. CO(2-1)-PdBI (contours) on Halpha/HST(colour) CO(2-1)-PdBI (contours) on V-I/HST(grey) NGC4579 V-I Ha AGN AGN  65pc ->AGN in off-centered 150pc gas disk with shell-like features seen in HST V-I and PdBI CO(2-1) maps.->Little molecular gas close to the AGN: closest molecular complex of ~a few105Msun at 80-100pc from BH.

    26. Seyferts m=1, 2 instabilities in NGC4579(García-Burillo et al 2004, A&A, in prep ) -> Any evidence of AGN fuelling?: molecular gas kinematics very complex from 500pc down to 50pc scales. ->’Odd’ gas kinematics on Northern spiral arm (~150-500pc). CO(2-1) Major Axis p-v plot CO(2-1) isovelocities -> Molecular gas kinematics in the inner 100pc disk suggestive of expanding motions? highly elliptical/non coplanar orbits?...-> AGN feeding still unclear ! (modelling in progress...)