All Figures

$\begin{figure} \par\includegraphics[width=18cm,clip]{8874fig1.eps} \end{figure}$ Figure 1: ¹²CO(1-0) velocity-channel maps observed with the PdBI in the nucleus of NGC 2782 with a spatial resolution of 2.1 $^{\prime \prime }$ $~\times~$ 1.5 $^{\prime \prime }$ at ${\rm PA}=38^{\circ }$ (beam is plotted as a filled ellipse in the bottom left corner of each panel). We show a field of view of 50 $^{\prime \prime }$ , i.e. $\sim$ 1.2 times the diameter of the primary beam at 115 GHz. The phase tracking center is indicated by a cross at $\alpha _{J2000}=09^{\rm h}14^{\rm m}05.08^{\rm s}$ and $\delta _{J2000}=40^{\circ }06'49.4''$ . Velocity-channels are displayed from v=-240 km s^-1 to v=240 km s^-1in steps of 10 km s^-1. Velocities are in LSR scale and refer to v=2562 km s^-1. Contour levels are -3 $\sigma$ , 3 $\sigma$ , 7 $\sigma$ , 12 $\sigma$ , 19 $\sigma$ , 30 $\sigma$ 40 $\sigma$ and 55 $\sigma$ where the rms $\sigma =2.0$ mJy beam^-1.
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In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{8874fig2.eps} \end{figure}$ Figure 2: Same as Fig. 1 but for the 2-1 line of ¹²CO. Spatial resolution reaches 0.7 $^{\prime \prime }$ $\times$ 0.6 $^{\prime \prime }$ at ${\rm PA}=20^{\circ }$ (beam is plotted as a filled ellipse in the bottom left corner of each panel). We show a field of view of 18 $^{\prime \prime }$ , i.e. $\sim$ 0.9 times the diameter of the the primary beam at 230 GHz. Velocity-channels are displayed from v=-240 km s^-1 to v=240 km s^-1 in steps of 10 km s^-1, with same reference as used in Fig. 1. Contour levels are -3 $\sigma$ , 3 $\sigma$ , 7 $\sigma$ , 10 $\sigma$ , 14 $\sigma$ and 18 $\sigma$ , where the rms $\sigma =5.2$ mJy beam^-1.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig3.eps} \end{figure}$ Figure 3: a) The natural-weight map in ¹²CO(1-0) shown in grey scale with contours ranging from 0.5 to 8.0 Jy km s^-1 in 1 Jy km s^-1 intervals. b) The uniform-weight map in ¹²CO(2-1) shown in grey scale with contours ranging from 1 to 7.0 Jy km s^-1 in 1 Jy km s^-1 intervals.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig4.eps} \end{figure}$ Figure 4: ¹²CO(1-0) a) and ¹²CO(2-1) b) isovelocities contoured over false-color velocity maps. The AGN (dynamical center) position is marked with a star.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig5.eps} \end{figure}$ Figure 5: a) Position-velocity diagram of ¹²CO(1-0) along the kinematic major axis of NGC 2782 (PA = 75 $^\circ$ ) contoured over a grey-scale representation. Velocities have been rescaled to $V_{\rm sys}$ = 2555 km s^-1, and offsets are relative to the dynamical center. b) The same for ¹²CO(2-1).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig6.eps} \end{figure}$ Figure 6: a) Position-velocity diagram of ¹²CO(1-0) along the kinematic minor axis of NGC 2782 (PA = 165 $^\circ$ ) contoured over a grey-scale representation. b) The same for ¹²CO(2-1).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig7.eps} \end{figure}$ Figure 7: a) ¹²CO(1-0) total intensity contoured over a false-color representation of the IRAC 3.6 $\mu$ m image of NGC 2782. The nuclear bar/oval and the outer oval can clearly be seen at ${\rm PA} \sim 88 ^\circ$ and $\sim$ 10 $^\circ$ , respectively. b) The same for ¹²CO(2-1). In both panels, the AGN (dynamical center) position is marked with a star.
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In the text

$\begin{figure} \par\mbox{\includegraphics[angle=-90,width=8.5cm,clip]{8874f8a.ps... ...e*{1mm} \includegraphics[angle=-90,width=8.5cm,clip]{8874f8b.ps} }\end{figure}$ Figure 8: a) IRAC 3.6 $\mu$ m image of NGC 2782. The stellar sheets to the east and west, and the ripples about $\sim$ 40 $^{\prime \prime }$ to the east are clearly visible. b) IRAC 3.6 $\mu$ m residuals from the bulge-to-disk decomposition described in Sect. 4.1, with contours superimposed.
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In the text

$\begin{figure} \par\includegraphics[width=16cm,clip]{8874fig9.ps} \end{figure}$ Figure 9: a) Shows CO(1-0) total intensity contours overlaid on the gray-scale residuals (in MJy/sr) of the bulge-disk decomposition performed on the 3.6 $\mu$ m IRAC image. b) Shows the analogous overlay of CO(2-1). The phase-tracking center is shown by a cross.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig10.eps} \end{figure}$ Figure 10: a) ¹²CO(1-0) total intensity contoured over a false-color representation of the HST/WFPC2 F814W image of NGC 2782. b) The same for ¹²CO(2-1). In both panels, the AGN (dynamical center) position is marked with a star.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig11.eps} \end{figure}$ Figure 11: a) ¹²CO(1-0) total intensity contoured over a false-color representation of the HST/WFPC2 V-I image of NGC 2782. The spiral arm to the northwest is clearly traced by the CO(1-0) emission. b) The same for ¹²CO(2-1). In both panels, the AGN (dynamical center) position is marked with a star.
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In the text

$\begin{figure} \par\includegraphics[width=9cm,angle=-90]{8874fig12.eps} \end{figure}$ Figure 12: a) ¹²CO(1-0) total intensity contoured over a false-color representation the IRAC 3.6 $\mu$ m image. Unlike Fig. 7, both the IRAC and the CO images have been deprojected onto the galaxy plane and rotated (by 15 $^\circ$ ) so that the major axis is horizontal; units on (x,y) axes ( $\Delta$ X_G/ $\Delta$ Y_G) correspond to arcsec offsets along the major/minor axes with respect to the AGN. The outer oval and stellar bar are marked by solid lines (in the deprojected rotated coordinate system). The image field-of-view is $\sim$ 2.2 kpc in diameter. The $\phi _i$ -angles are measured from the +X axis in the counter-clockwise direction. b) The same for ¹²CO(2-1).
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In the text

$\begin{figure} \par\includegraphics[width=6cm,angle=-90, bb=56 35 297 720]{8874fig13.ps} \end{figure}$ Figure 13: a) The different normalised Fourier components Q_m (defined in Eq. (3), as the maximum tangential force, normalised to the radial force), for the potential of NGC 2782, derived from the NIR image. The top solid line is the total tangential force Q_t, the next solid line is Q₂, the dashed line Q₁, the dotted line Q₃, and the dotted-dashed one Q₄. b) The corresponding phases $\theta _m$ in radians, defined in Eq. (1), with the lines as in the left panel.
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In the text

$\begin{figure} \par\includegraphics[width=18cm]{8874fig14.eps} \end{figure}$ Figure 14: a) ¹²CO(1-0) total intensity contoured over a false-color representation of the torque maps $\tau$ derived as described in the text. As in Fig. 12, this is the deprojected representation, with units on (x,y) axes ( $\Delta$ X_G/ $\Delta$ Y_G) corresponding to arcsec offsets along the major/minor axes with respect to the AGN. The torque exerted on the spiral arm to the south is clearly associated with the outer oval. b) The same for ¹²CO(2-1). Both panels show the typical butterfly diagram due to an m=2 perturbation, and in b) we have marked the four quadrants with their positive (I, III) and negative torques (II, IV) which drive the gas outward and inward, respectively. As described in the text, the sign of the torques is determined by the rotation direction of the gas, namely clockwise in NGC 2782.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig15.eps} \end{figure}$ Figure 15: a) The relative torque in dimensionless units of ${\rm d}L/L$ derived using the potential obtained from the Spitzer/IRAC 3.6 $\mu$ m image (1.2 $^{\prime \prime }$ pixels, undersampled beam). b) The same for ¹²CO(2-1). The ¹²CO(2-1) emission is less well sampled than ¹²CO(1-0) beyond a radius of $\sim$ 1.9 kpc, because of the smaller beam size ( ${\it FWHP} \sim 22$ $^{\prime \prime }$ ). Despite the relatively poor resolution of the gravitational potential image, both CO transitions give similar results; we see systematically negative average torques within the entire region probed by our observations.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,bb=17 300 590 713]{8874fig16.ps}\end{figure}$ Figure 16: Rotation and derived frequency curves $\Omega$ , $\Omega -\kappa /2$ and $\Omega +\kappa /2$ adopted for the simulations (Run A), together with the empirical curves derived from the CO(2-1) and (1-0) PV diagrams. The (green) open circles trace the empirical $V_{\rm rot}$ , coinciding with theoretical circular velocity $V_{\rm circ}$ (traced by a solid line) at R =1 kpc and at small radii. The remaining solid lines are the empirical (black) and theoretical (green) $\Omega$ curves. The long-dashed line is the $\Omega$ - $\kappa /4$ curve, and the short-dashed ones are the $\Omega \pm \kappa /2$ ones. The corresponding data points are shown as $\times$ and +; the data have been masked within 500 pc to minimize confusion. The two pattern speeds inferred from the simulations are shown as horizontal dotted lines, and resonances are marked with filled circles. The vertical dashed lines correspond to the nuclear bar length ( $\sim$ 1 kpc) and the ILR of the outer oval ( $\sim$ 1.3 kpc), also roughly equal to the nuclear bar's CR at $\sim$ 1.1 kpc. The apparent mismatch of the empirical and theoretical RCs, in the range of 200-800 pc, is due to non-circular streaming motions (Sect. 3.2) and asymmetry in the two sides of the rotation curve (Sect. 3.3) which contribute to the inferred average $V_{\rm rot}$ .
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In the text

$\begin{figure} \par\rotatebox{0}{\includegraphics[angle=-90,width=18cm]{8874fig17.ps}} \end{figure}$ Figure 17: Left panel: false-color plot of the stellar component distribution, in Run A (the intensity scale is linear and axes are in kpc). Middle: false-color plot of the corresponding gaseous component (the intensity scale is logarithmic). Right: same as the middle panel, but with an expanded spatial scale. It can be seen that the gas which was predominantly in the more external ring (ILR of the primary bar) at T = 690 Myr, is falling progressively inward, and is primarily inside the ILR at T=750 Myr. The gas infalling along the ``dust lanes'' is aligned along the nuclear bar, where the CO is observed in NGC 2782.
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In the text

$\begin{figure} \par\rotatebox{-90}{\includegraphics[width=6.8cm]{8874fig18.ps}}\end{figure}$ Figure 18: Left: intensity of the m=2 and m=4 Fourier components of the potential in Run A, during the second bar decoupling. Right: power spectrum of the m=2 Fourier component, giving the pattern speed as a function of radius, during a period of 100 Myr corresponding to the coexistence of the two bars. Since the pattern speed of the nuclear bar varies with time during this period, its $\Omega _{\rm b}$ signature is somewhat widened.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig3.eps} \end{figure}$	Figure 3: a) The natural-weight map in ¹²CO(1-0) shown in grey scale with contours ranging from 0.5 to 8.0 Jy km s^-1 in 1 Jy km s^-1 intervals. b) The uniform-weight map in ¹²CO(2-1) shown in grey scale with contours ranging from 1 to 7.0 Jy km s^-1 in 1 Jy km s^-1 intervals.
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$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig4.eps} \end{figure}$	Figure 4: ¹²CO(1-0) a) and ¹²CO(2-1) b) isovelocities contoured over false-color velocity maps. The AGN (dynamical center) position is marked with a star.
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$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig5.eps} \end{figure}$	Figure 5: a) Position-velocity diagram of ¹²CO(1-0) along the kinematic major axis of NGC 2782 (PA = 75 $^\circ$ ) contoured over a grey-scale representation. Velocities have been rescaled to $V_{\rm sys}$ = 2555 km s^-1, and offsets are relative to the dynamical center. b) The same for ¹²CO(2-1).
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$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig6.eps} \end{figure}$	Figure 6: a) Position-velocity diagram of ¹²CO(1-0) along the kinematic minor axis of NGC 2782 (PA = 165 $^\circ$ ) contoured over a grey-scale representation. b) The same for ¹²CO(2-1).
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$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig7.eps} \end{figure}$	Figure 7: a) ¹²CO(1-0) total intensity contoured over a false-color representation of the IRAC 3.6 $\mu$ m image of NGC 2782. The nuclear bar/oval and the outer oval can clearly be seen at ${\rm PA} \sim 88 ^\circ$ and $\sim$ 10 $^\circ$ , respectively. b) The same for ¹²CO(2-1). In both panels, the AGN (dynamical center) position is marked with a star.
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$\begin{figure} \par\mbox{\includegraphics[angle=-90,width=8.5cm,clip]{8874f8a.ps... ...e*{1mm} \includegraphics[angle=-90,width=8.5cm,clip]{8874f8b.ps} }\end{figure}$	Figure 8: a) IRAC 3.6 $\mu$ m image of NGC 2782. The stellar sheets to the east and west, and the ripples about $\sim$ 40 $^{\prime \prime }$ to the east are clearly visible. b) IRAC 3.6 $\mu$ m residuals from the bulge-to-disk decomposition described in Sect. 4.1, with contours superimposed.
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$\begin{figure} \par\includegraphics[width=16cm,clip]{8874fig9.ps} \end{figure}$	Figure 9: a) Shows CO(1-0) total intensity contours overlaid on the gray-scale residuals (in MJy/sr) of the bulge-disk decomposition performed on the 3.6 $\mu$ m IRAC image. b) Shows the analogous overlay of CO(2-1). The phase-tracking center is shown by a cross.
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$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig10.eps} \end{figure}$	Figure 10: a) ¹²CO(1-0) total intensity contoured over a false-color representation of the HST/WFPC2 F814W image of NGC 2782. b) The same for ¹²CO(2-1). In both panels, the AGN (dynamical center) position is marked with a star.
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$\begin{figure} \par\includegraphics[width=8.8cm]{8874fig11.eps} \end{figure}$	Figure 11: a) ¹²CO(1-0) total intensity contoured over a false-color representation of the HST/WFPC2 V-I image of NGC 2782. The spiral arm to the northwest is clearly traced by the CO(1-0) emission. b) The same for ¹²CO(2-1). In both panels, the AGN (dynamical center) position is marked with a star.
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