All Figures

$\begin{figure} \par\includegraphics[width=15.4cm,clip]{ONLINE/2900f1.eps} \end{figure}$ Figure 1: a) The ¹²CO(1-0) integrated intensity map obtained with the PdBI (contour levels from 1.5 to 5 in steps of 0.5 Jy km s^-1 beam^-1 and from 5 to 10 in steps of 1 Jy km s^-1 beam^-1) observed in the nucleus of NGC 4321. The filled ellipse at the top right corner represents the CO beam size. The central $r\sim 1$ kpc molecular disk of NGC 4321 consists of two nuclear spiral arms connected (e.g., B component) to a marginally resolved $r\sim 150$ pc disk of $\sim$ 10⁸ $M_{\odot }$ of molecular gas centered on the AGN locus (highlighted by the star marker). ( $\Delta \alpha$ , $\Delta \delta$ )-offsets are with respect to the location of the AGN [(RA₂₀₀₀, Dec₂₀₀₀) = (12 $^{\rm h}$ 22 $^{\rm m}$ 54.91 $^{\rm s}$ , 15 $^{\rm d}$ 49 $^{\rm m}$ 19.9 $^{\rm s}$ )]. This position coincides within the errors with a secondary radio continuum maximum measured at 6 cm by Weiler et al. (1981) and with a peak in the (J, H, K)-2MASS image of the galaxy (Jarrett et al. 2003). b) Illustrates the kinematics of molecular gas along the strip at PA = 127 $^{\circ }$ (thick line in a). Levels go from 0.015 to 0.14 in steps of 0.0125 Jy beam^-1. Velocities are relative to the systemic velocity ( $v_{\rm sys}^{\rm LSR}=1573$ km s^-1; determined from CO kinematics by García-Burillo et al. 1998) and $\Delta x$ offsets are relative to the AGN. The major axis orientation is shown by the dashed line. Gas kinematics over the emission bridge B depart from circular rotation.
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In the text

$\begin{figure} \par\includegraphics[width=15.4cm,clip]{ONLINE/2900f2.eps} \end{figure}$ Figure 2: a) The ¹²CO(2-1) integrated intensity map obtained with the PdBI (contour levels from 2.8 to 10 in steps of 0.9 Jy km s^-1 beam^-1) is overlaid on the B-I color image from HST (grey scale) observed in the nucleus of NGC 4826. The filled ellipse at the top right corner represents the CO beam size. ( $\Delta \alpha$ , $\Delta \delta$ )-offsets are with respect to the location of the AGN (marked by the star): (RA₂₀₀₀, Dec₂₀₀₀) = (12 $^{\rm h}$ 56 $^{\rm m}$ 43.63 $^{\rm s}$ , 21 $^{\rm d}$ 40 $^{\rm m}$ 59.1 $^{\rm s}$ ). The AGN locus is identified by a blue point-like source in the B-I map; it also coincides with a non-thermal radio continuum peak measured at 6 cm by Turner & Ho (1994). The 80 pc radius circumnuclear disk (CND) of NGC 4826, with $\sim$ 3 $\times$ 10⁷ $M_{\odot }$ of molecular gas, shows a lopsided ringed disk morphology; the disk is off-center with respect to the AGN. b) The kinematics of the gas, here displayed along the minor-axis p-v plot (thick line in a), are suggestive of strong streaming motions at the crossing of the ring edges (N, S). Levels go from 0.025 to 0.19 in steps of 0.015 Jy beam^-1. Velocities are relative to the systemic velocity ( $v_{\rm sys}^{\rm LSR}=413$ km s^-1; determined from CO kinematics by García-Burillo et al. 2003b) and $\Delta y$ offsets are relative to the AGN.
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In the text

$\begin{figure} \par\includegraphics[width=15.4cm,clip]{ONLINE/2900f3.eps} \end{figure}$ Figure 3: a) The ¹²CO(2-1) integrated intensity map obtained with the PdBI (contour levels from 0.4, 0.7, 1.3, 2.0 to 11 in steps of 0.9 Jy km s^-1 beam^-1) is overlaid on the V-I color image from HST (grey scale) observed in the nucleus of NGC 4579. The filled ellipse at the top right corner represents the CO beam size. ( $\Delta \alpha$ , $\Delta \delta$ )-offsets are with respect to the location of the AGN (marked by the star): (RA₂₀₀₀, Dec₂₀₀₀) = (12 $^{\rm h}$ 37 $^{\rm m}$ 43.52 $^{\rm s}$ , 11 $^{\rm d}$ 49 $^{\rm m}$ 05.5 $^{\rm s}$ ). The AGN locus is identified by a point-like continuum source detected at 3 mm and 1 mm by García-Burillo et al. (2005, in prep.). Two spiral arcs concentrate the bulk of the $\sim$ 3.2 $\times$ 10⁸ $M_{\odot }$ molecular gas mass in the central 1 kpc of the galaxy. A close-up view of the inner 200 pc region (shown in c), shows a central ringed disk (highlighted by the dashed ellipse) with the AGN lying on its southwestern edge. A gas clump of $\sim$ 10⁶ $M_{\odot }$ (denoted as E) delimits the disk to the East. b) The kinematics along the major axis (thick line in a)) reveal highly non-circular motions related to the E clump. Levels go from 0.006 to 0.09 in steps of 0.006 Jy beam^-1. Velocities are relative to the systemic velocity ( $v_{\rm sys}^{\rm LSR}=1469$ km s^-1; determined from CO kinematics by García-Burillo et al. 2005, in prep.) and $\Delta x$ offsets are relative to the AGN. d) Same as b) but here along the declination axis (dashed thick line in a)) with levels going from 0.006 to 0.024 in steps of 0.006 Jy beam^-1. Highly non-circular motions are related to the N clump.
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In the text

$\begin{figure} \par\includegraphics[width=16cm,clip]{ONLINE/2900f4.eps} \end{figure}$ Figure 4: a) The ¹²CO(2-1) integrated intensity map obtained with the PdBI (contour levels from 0.15, 0.25, 0.40, 0.70 to 6.2 in steps of 0.5 Jy km s^-1 beam^-1) is overlaid on the J-H color image from HST (grey scale) observed in the nucleus of NGC 6951. The filled ellipse at the top right corner represents the CO beam size. ( $\Delta \alpha$ , $\Delta \delta$ )-offsets are with respect to the location of the AGN (marked by the star): (RA₂₀₀₀, Dec₂₀₀₀) = (20 $^{\rm h}$ 37 $^{\rm m}$ 14.12 $^{\rm s}$ , 66 $^{\rm d}$ 06 $^{\rm m}$ 20.0 $^{\rm s}$ ). The position of the AGN is given by the point-like radio continuum source measured at 6 cm and 20 cm by Ho & Ulvestad (2001). The molecular gas distribution in the central 1 kpc shows two highly contrasted nuclear spiral arms containing $3\times 10$ ⁸ $M_{\odot }$ which are presently feeding a circumnuclear starburst. A compact molecular complex (denoted as G) of $\sim$ a few 10⁶ $M_{\odot }$ is detected on the AGN. Furthermore, we have tentatively detected a northern molecular gas component linking G with the N spiral arm (i.e., the spiral running North from West) which could be related to the filamentary dusty spiral seen in the J-H color HST image (see also b)). b) The kinematics along the major axis (thick line in a)) are compatible with circular motions for the gas near the AGN. Levels go from 0.008, 0.0012, 0.016 to 0.076 in steps of 0.006 Jy beam^-1. Velocities are relative to the systemic velocity ( $v_{\rm sys}^{\rm LSR}=1441$ km s^-1; determined from CO kinematics by Schinnerer et al. 2005, in prep.) and $\Delta x$ offsets are relative to the AGN.
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In the text

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{ONLINE/2900f5a.eps}\vspace*{4mm} \includegraphics[width=8.3cm,clip]{ONLINE/2900f5b.eps} \end{figure}$ Figure 5: a) ( Upper panel) We overlaid the ¹²CO(1-0) PdBI intensity map (contours) on the K-band image of Knapen et al. (1995) (grey scale) obtained for the nucleus of NGC 4321; both images have been deprojected onto the galaxy plane. Units on X/Y axes ( $\Delta X_{\rm G}$ / $\Delta Y_{\rm G}$ ) correspond to arcsec offsets along the major/minor axes with respect to the AGN. The nuclear bar - BAR(n) - is parallel to the large-scale bar-BAR. b) ( Lower panels) Strengths (Q_i, i=1,2) and phases ( $\phi _i$ , i=1,2) of the m=1 and m=2-Fourier components of the stellar potential inside the image field-of-view (r=1100 pc). The $\phi _i$ -angles are measured from the +X axis in the counter-clockwise direction. The total strength of the potential is represented by $Q_{\rm T}$ . Q-values for r<50 pc (not shown) are blanked due to insufficient grid sampling close to the nucleus.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{ONLINE/2900f6a.eps}\par\vspace*{3mm} \includegraphics[width=8.2cm,clip]{ONLINE/2900f6b.eps} \end{figure}$ Figure 6: a) ( Upper panel) We overlaid the ¹²CO(2-1) PdBI intensity map (contours) on the H-band HST image (grey scale) obtained for the nucleus (r<200 pc) of NGC 4826; both images have been deprojected onto the galaxy plane. The orientation of the nuclear oval perturbation-OVAL(n)-is shown. b) ( Lower panels) As in Fig. 5, we plot (Q_i, i=1,2), ( $\phi _i$ , i=1,2) and $Q_{\rm T}$ inside the image field-of-view (r=530 pc) with an inner truncation radius r=10 pc.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{ONLINE/2900f7a.eps} \includegraphics[width=8.2cm,clip]{ONLINE/2900f7b.eps} \end{figure}$ Figure 7: a) ( Upper panel) We overlaid the ¹²CO(2-1) PdBI intensity map (contours) on the I-band HST image (grey scale) obtained for the nucleus of NGC 4579; both images have been deprojected onto the galaxy plane. The orientation of the large-scale 9 kpc bar-BAR-is shown. b) ( Lower panels) As in Fig. 5, we plot (Q_i, i=1,2), ( $\phi _i$ , i=1,2) and $Q_{\rm T}$ inside r=1200 pc with an inner truncation radius r=50 pc.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{ONLINE/2900f8a.eps} \includegraphics[width=8.2cm,clip]{ONLINE/2900f8b.eps} \end{figure}$ Figure 8: a) ( Upper panel) We overlaid the ¹²CO(2-1) PdBI intensity map (contours) on the J-band HST image (grey scale) obtained for the nucleus of NGC 6951; both images have been deprojected onto the galaxy plane. We indicate the orientation of the large-scale bar-BAR-and of the nuclear oval distortion-OVAL(n)-that is detected in the HST image at r<500 pc. b) ( Lower panels) As in Fig. 5, we plot (Q_i, i=1,2), ( $\phi _i$ , i=1,2) and $Q_{\rm T}$ inside the image field-of-view (r=900 pc) with an inner truncation radius r=25 pc.
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In the text

$\begin{figure} \par\includegraphics[width=15.5cm,clip]{ONLINE/2900f9.eps} \end{figure}$ Figure 9: a) ( Left) We overlay the ¹²CO(1-0) contours with the map of the effective angular momentum variation (t(x,y) $\times$ N(x,y), as defined in the text) in the nucleus of NGC 4321. The grey scale is normalized to the maximum absolute value in the map, i.e., [ $\vert N(x,y) \times t(x,y) \vert ]_{\rm max}$ . The derived torques change sign as expected if the butterfly diagram, defined by the orientation of quadrants I-to-IV, can be attributed to the action of the nuclear bar of NGC 4321. b) ( Right) The torque per unit mass averaged over azimuth - t(r) - and the fraction of the angular momentum transferred from/to the gas in one rotation - dL/L - are plotted. Torques are strong and positive for the bulk of the molecular gas in NGC 4321. This includes the vicinity of the AGN. Torques are negative but comparatively weaker on intermediate scales ( r=250-550 pc) and in the outer disk r>900 pc.
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In the text

$\begin{figure} \par\includegraphics[width=15.5cm,clip]{ONLINE/2900f10.eps} \end{figure}$ Figure 10: Same as Fig. 9 but for NGC 4826, using the ¹²CO(2-1) map in the overlay and the ¹²CO(1-0) map in the radial averages. The derived torques change sign as expected if the butterfly diagram, defined by the orientation of quadrants I-to-IV, can be attributed to the action of the oval distortion of NGC 4826. Stellar torques are weak and mostly positive in the nucleus of NGC 4826 at present.
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In the text

$\begin{figure} \par\includegraphics[width=16cm,clip]{ONLINE/2900f11.eps} \end{figure}$ Figure 11: Same as Fig. 10 but for NGC 4579. The torques change sign as expected if the butterfly diagram, defined by the orientation of quadrants I-to-IV, can be attributed to the action of the large-scale bar of NGC 4579. Torques are systematically strong and negative for the bulk of the molecular gas in NGC 4579, from r=200 pc out to r=1200 pc. In the vicinity of the AGN, however, torques become positive and AGN feeding is not presently favored.
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In the text

$\begin{figure} \par\includegraphics[width=16cm,clip]{ONLINE/2900f12.eps} \end{figure}$ Figure 12: Same as Fig. 10 but for NGC 6951. The torques change sign as expected if the butterfly diagram, defined by the orientation of quadrants I-to-IV, can be attributed to the action of the nuclear oval rather than to that of the outer bar of NGC 6951. Torques are systematically negative over the nuclear spiral arms down to the inner radius of the pseudo-ring, $r\sim 300$ pc. In the vicinity of the AGN, torques become positive and AGN feeding is not presently favored.
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In the text

$\begin{figure} \par\includegraphics[width=8cm]{ONLINE/2900f13.eps} \end{figure}$ Figure 13: a) ( Upper panel) We represent the radial variation of the mass inflow(-) or outflow(+) rate of gas per unit radial length in the nucleus of NGC 4321 due to the action of stellar gravitational torques. Units are $M_{\odot }$ yr^-1 pc^-1. b)( Lower panel) Here we plot the mass inflow/outflow rate integrated inside a certain radius r in $M_{\odot }$ yr^-1. As is the case of the other transition object, NGC 4826, the overall budget in NGC 4321 is clearly positive at all radii.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{ONLINE/2900f14.eps} \end{figure}$ Figure 14: Same as Figs. 13a,b but for NGC 4826. As is the case of the other transition object, NGC 4321, the overall budget in NGC 4826 is clearly positive at all radii.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{ONLINE/2900f15.eps} \end{figure}$ Figure 15: Same as Figs. 13a,b but for NGC 4579. The overall mass inflow budget is clearly negative down to r=300 pc due to the action of the large-scale bar. Inside this radius, stellar torques do not favour AGN feeding in this LINER/Seyfert.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{ONLINE/2900f16.eps} \end{figure}$ Figure 16: Same as Figs. 13a,b but for NGC 6951. The overall mass inflow budget is clearly negative down to r=300 pc due to the combined action of the large-scale bar and the nuclear oval. Inside this radius, stellar torques do not favour AGN feeding in this Seyfert.
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In the text

$\begin{figure} \par\includegraphics[width=6cm,clip]{ONLINE/2900f17.eps} \end{figure}$ Figure 17: a) The time evolution of gas surface density in an axisymmetric disk, where the rotation curve is of the form: $V_{\rm rot} \propto r^{1-\alpha }$ , with $\alpha =0.1$ . To normalize, we fit $V_{\rm rot}=200$ km s^-1 at r=1 kpc. Initially the gas is distributed according to a surface density law proportional to $\Sigma \propto 1+ \cos (\pi r/r_{\rm c})$ , until the cut-off radius $r_{\rm c} = 0.3$ kpc. We represent Log $_{10}\Sigma (r,t)$ in arbitrary units. The various curves are the evolution for times spaced by 2 $\times$ 10⁷ yr, until 2 $\times~$ 10⁸. The column density profile shows hardly any change after 2 $\times$ 10⁸ yr. b) Same as a) but here for an initial gas distribution in the shape a narrow ring between 90 and 110 pc radii (top-hat profile). The $\Sigma (r,t)$ profile changes significantly already after 5 $\times$ 10⁷yr.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{ONLINE/2900f14.eps} \end{figure}$	Figure 14: Same as Figs. 13a,b but for NGC 4826. As is the case of the other transition object, NGC 4321, the overall budget in NGC 4826 is clearly positive at all radii.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{ONLINE/2900f15.eps} \end{figure}$	Figure 15: Same as Figs. 13a,b but for NGC 4579. The overall mass inflow budget is clearly negative down to r=300 pc due to the action of the large-scale bar. Inside this radius, stellar torques do not favour AGN feeding in this LINER/Seyfert.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{ONLINE/2900f16.eps} \end{figure}$	Figure 16: Same as Figs. 13a,b but for NGC 6951. The overall mass inflow budget is clearly negative down to r=300 pc due to the combined action of the large-scale bar and the nuclear oval. Inside this radius, stellar torques do not favour AGN feeding in this Seyfert.
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