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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),

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Presentation on theme: "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),"— Presentation transcript:

1 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). (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 -> 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? Where do we stand...? ( Combes ; Wada et al ; 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 and many others!)

3 -> CO : best tracer of distribution and kinematics of molecular gas in nuclei. -> High spatial resolution (0.5’’-1”) paramount to reach ‘critical’ scales: 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 galaxies by including PdBI data available from consortium members. NUclei of GAlaxies: the NUGA project NUGA: a CO survey of low-L AGN with IRAM Bure Interferometer -> 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. Strategy for NUGA : -> 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 T/LINER LINER/SEYF. 1 LINER HII/T SEYF. 1 SEYF. 2 LINERT/LINER SEYF. 2 T/SEYF. 2

5 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 tens to several hundreds of pc. NGC4826NGC1961 0’’.6 (=12pc) CO(2-1) map of NGC4826 shows molecular gas distribution lopsided near AGN.  LINERT/LINER NUGA reveals m=1 instabilities 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) 20pc 500pc

6 I/ TRANSITION objects: NGC4826 CO(2-1 )(contours)-on B-I /HST(colours) (Garcia-Burillo et al 2003, A&A, 407; and 2004 in prep) ->NGC4826 is a 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<80-100pc -> Analysis of observed streaming motions suggests inner instabilities are ‘fast’ trailing m=1 perturbations......Inner instabilities would not drive AGN fueling!. Searching for observational evidences of ‘ongoing’ feeding... ->Kinematical signature of lopsided nuclear disk along minor axis suggestive of outflow rather than inflow near AGN. CO(2-1 ) p-v diagram along minor axis ->Large molecular gas concentration at radii ~ pc from the AGN (0.5x10 8 M sun ), but negative evidence of inflow from gas kinematics. Conclusion pc

7 II/ LINERS: NGC4579 (Garcia-Burillo et al 2004 in prep) Searching for observational evidences of ‘ongoing’ feeding... -> Molecular gas kinematics in the inner 100pc disk (~10 5 M sun )suggestive of expanding motions? highly elliptical/non coplanar orbits?... AGN feeding issue still unclear ! (modelling in progress...) Conclusion.... -> 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 ) p-v diagram along major axis CO(2-1 )(contours)-on V-I /HST(colours) Kinematical signature of highly non-circular motions for gas on major axis p-v plot near AGN (<100pc) 70pc AGN

8 -> 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 (~4x10 8 M sun ) 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 -> CO(2-1) central clump on the AGN of ~10 6 M sun betrays feeding in the past. -> NW gas extension of ~10 7 M sun linked to filamentary dusty spiral in J-H HST map is tantalazing evidence of ongoing feeding CO(2-1) Major Axis p-v plots 200pc Searching for observational evidences of ‘ongoing’ feeding... III/ SEYFERTS: NGC6951 (Schinnerer et al 2004 in prep) Conclusion....

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. Deriving potentials... I

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

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

12 Gravitational Torques in NGC4826 (Garcia-Burillo, Combes, Schinnerer et al 2004 in prep) I/ TRANSITION objects 40pc Torques Map Efficiency of Torques ->Torques map reproduces butterfly-like pattern driven by the stellar oval for r<100pc, roughly oriented N/S. ->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 Stellar perturbations have virtually no role in AGN feeding at present

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

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

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

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

17 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 NUGA maps show wide range of instabilities at r~ pc from AGN. This includes all types of m=2 and m=1-like perturbations. Summary 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?)) Perturbations seen in NUGA maps can be either self-gravitating (low Q) or non self- gravitating (high Q).

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

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

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

21 NGC7217  12 CO(1-0) (top) and 12 CO(2-1) (bottom) maps overlaid with HST V-I image -> 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 < 10 6 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! Self-Gravitating Non Self-Gravitating...and m=2 instabilities (Combes et al 2004, A&A, 414)

22 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 LINERS Rings and spirals in NGC7217 (Combes et al 2004, A&A,414 )

23 -> 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!. Isovelocity maps in N4826 m=1 instabilities in NGC4826 (Garcia-Burillo et al 2003, A&A, 407) NGC4826 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. Transition

24 -> 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 Q maps in NGC4826: Gas self-gravity T/LINERS m=1 instabilities in NGC4826 (Garcia-Burillo et al 2003, A&A, 407)

25 Seyferts m=1, 2 instabilities in NGC4579 (García-Burillo et al 2004, A&A, in prep ) CO(2-1)- PdBI (contours) on V-I /HST(grey) CO(2-1)- PdBI (contours) on Halpha /HST(colour) NGC4579 -> 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!. AGN -> 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 few10 5 M sun at pc from BH.  65pc V-IHa

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 (~ pc). CO(2-1) isovelocities CO(2-1) Major Axis p-v plot -> Molecular gas kinematics in the inner 100pc disk suggestive of expanding motions? highly elliptical/non coplanar orbits?... -> AGN feeding still unclear ! (modelling in progress...)


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