All Figures

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{4976fig1.eps}\end{figure}$ Figure 1: Model galaxy A (gas (blue) and stars (yellow) are shown) and a virtual slit for extracting a rotation curve. The slit width d is indicated by the red lines. A coordinate system as used in the text (see Sect. 2.1) is shown.
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In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{4976fig2.eps}\end{figure}$ Figure 2: Top left: luminosity field derived from the stellar-mass distribution; top right: the unsmoothed and unweighted velocity field of the gas. A virtual slit is indicated and a small part of the gaseous disc of the second galaxy is visible on the right hand side. Bottom left: the extracted RC for the modelled galaxy (dashed line) with 1 $\sigma$ errors (solid lines). For this image series we use galaxy A in an early stage of an interaction (unequal mass merger).
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{4976fig3.eps}\end{figure}$ Figure 3: Rotation curve extracted from one of our modelled systems along the major axis using two different assumptions for the mass-to-light ratio. The dashed line corresponds to a constant mass-to-light ratio, while the solid line was extracted using a linear decreasing M/L with a slope of 0.1 kpc^-1.
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In the text

$\begin{figure} \par\includegraphics[width=17cm,clip]{4976fig4.eps}\end{figure}$ Figure 4: Sketch to illustrate the parameters used to define the interaction geometry. Figure from Kapferer et al. (2005). See also Duc et al. (2000) for further descriptions.
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In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{4976fig5.eps}\end{figure}$ Figure 5: Gaussian smoothed images of the luminosity field of the galaxies, derived from the stellar mass distribution and with the assumption of a constant mass-to-light ratio. The images a) to d) correspond to the images in Fig. 6 but observed under an inclination angle of 10 $^\circ$ . The sequence shows an unequal mass merger, where image a) represents 0.5 Gyr, b) 0.6 Gyr, c) 1 Gyr, and d) 2 Gyr of evolution. More details about the smoothing are listed in Sect. 2.1.
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{4976fig6.eps}\end{figure}$ Figure 6: Sequence of images corresponding to different time steps in the merging process, with only the gas shown. The evolution of the system is calculated over 5 Gyr. Here a) represents 0.5 Gyr, b) 0.6 Gyr, c) 1 Gyr, and d) 2 Gyr of evolution.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{4976fig7.eps}\end{figure}$ Figure 7: Rotation curves for an unequal mass merger (galaxies A and B) for different time steps, corresponding to the time series shown in Fig. 6 but observed under an inclination of $i=80^\circ$ . The red lines always indicate the centre of galaxy A to highlight asymmetries in the RCs.
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In the text

$\begin{figure} \par\includegraphics[width=7.2cm,clip]{4976fig8.eps}\end{figure}$ Figure 8: Rotation curve of model galaxy A (blue, dashed line) 1.4 Gyr after the first encounter with model galaxy B, i.e. after 2 Gyr of evolution, as compared to the rotation curve of the isolated model galaxy A (red, solid line) after 2 Gyr of isolated evolution.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{4976fig9.eps}\end{figure}$ Figure 9: Rotation curves for an equal mass merger for different time steps corresponding to the interaction geometry illustrated in the lower panel. The galaxy from which the RC was extracted is highlighted. Here panel a) shows the system after 1.1 Gyr and panel b) after 2 Gyr of evolution.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{4976fig10.eps}\end{figure}$ Figure 10: Sketch to illustrate the decrease in the rotational velocities in the outer parts of the RCs that can be caused by gas from the tidal tail, which has small radial velocity components at this projected position and is covered by the slit.
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In the text

$\begin{figure} \par\includegraphics[width=7.9cm,clip]{4976fig11.eps}\end{figure}$ Figure 11: Rotation curves for different snapshots of a fly-by of two model galaxies B. In the lower panel the alignment of the system and in the upper panel the corresponding rotation curves of the highlighted galaxy are shown. Here a) represents 0.5 Gyr, b) 1.7 Gyr, c) 2 Gyr, and d) 3 Gyr of evolution.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{4976fig12.eps}\end{figure}$ Figure 12: Rotation curves for the first encounter of model galaxy A and B seen nearly edge on ( $i=80^\circ$ ) from different viewing angles. The geometry is illustrated by the image series on the left hand side. The snapshot corresponds to panel b) in Fig. 6 and therefore shows the system after 0.6 Gyr of evolution.
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In the text

$\begin{figure} \par\includegraphics[width=6.5cm,clip]{4976fig13.eps}\end{figure}$ Figure 13: Rotation curves for model galaxy A after an equal mass merger from different viewing angles. The geometry is illustrated by the image series on the left hand side. The snapshot corresponds to panel b) in Fig. 9 and therefore shows the system after 2 Gyr of evolution. The change in the sign of the velocity gradient does not appear for all viewing angles.
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In the text

$\begin{figure} \par\includegraphics[width=16.2cm,clip]{4976fig14.eps}\end{figure}$ Figure 14: ACS images taken in the F814 filter and rotation curves from the VLT/FORS spectroscopy of four galaxies in the distant cluster MS 0451.5-0305 at z=0.53. Tentatively, we find evidence for, e.g., tidal streams ( upper panel left, cf. Fig. 8) or a recent close fly-by/merger ( lower panel right, cf. Fig. 10). Note that the rotation curves give the observed values of the rotational velocity $V_{\rm rot}$ ; i.e. they are not corrected for inclination or offset angles ( $\delta$ ) between the slit directions and the galaxies' major axes. The indicated rectangles correspond to the extensions of the derived RCs.
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In the text

$\begin{figure} \par\includegraphics[width=8.2cm,clip]{4976fig1.eps}\end{figure}$	Figure 1: Model galaxy A (gas (blue) and stars (yellow) are shown) and a virtual slit for extracting a rotation curve. The slit width d is indicated by the red lines. A coordinate system as used in the text (see Sect. 2.1) is shown.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{4976fig3.eps}\end{figure}$	Figure 3: Rotation curve extracted from one of our modelled systems along the major axis using two different assumptions for the mass-to-light ratio. The dashed line corresponds to a constant mass-to-light ratio, while the solid line was extracted using a linear decreasing M/L with a slope of 0.1 kpc^-1.
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$\begin{figure} \par\includegraphics[width=17cm,clip]{4976fig4.eps}\end{figure}$	Figure 4: Sketch to illustrate the parameters used to define the interaction geometry. Figure from Kapferer et al. (2005). See also Duc et al. (2000) for further descriptions.
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$\begin{figure} \par\includegraphics[width=7.6cm,clip]{4976fig6.eps}\end{figure}$	Figure 6: Sequence of images corresponding to different time steps in the merging process, with only the gas shown. The evolution of the system is calculated over 5 Gyr. Here a) represents 0.5 Gyr, b) 0.6 Gyr, c) 1 Gyr, and d) 2 Gyr of evolution.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{4976fig7.eps}\end{figure}$	Figure 7: Rotation curves for an unequal mass merger (galaxies A and B) for different time steps, corresponding to the time series shown in Fig. 6 but observed under an inclination of $i=80^\circ$ . The red lines always indicate the centre of galaxy A to highlight asymmetries in the RCs.
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$\begin{figure} \par\includegraphics[width=7.2cm,clip]{4976fig8.eps}\end{figure}$	Figure 8: Rotation curve of model galaxy A (blue, dashed line) 1.4 Gyr after the first encounter with model galaxy B, i.e. after 2 Gyr of evolution, as compared to the rotation curve of the isolated model galaxy A (red, solid line) after 2 Gyr of isolated evolution.
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$\begin{figure} \par\includegraphics[width=7.5cm,clip]{4976fig9.eps}\end{figure}$	Figure 9: Rotation curves for an equal mass merger for different time steps corresponding to the interaction geometry illustrated in the lower panel. The galaxy from which the RC was extracted is highlighted. Here panel a) shows the system after 1.1 Gyr and panel b) after 2 Gyr of evolution.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{4976fig10.eps}\end{figure}$	Figure 10: Sketch to illustrate the decrease in the rotational velocities in the outer parts of the RCs that can be caused by gas from the tidal tail, which has small radial velocity components at this projected position and is covered by the slit.
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$\begin{figure} \par\includegraphics[width=7.9cm,clip]{4976fig11.eps}\end{figure}$	Figure 11: Rotation curves for different snapshots of a fly-by of two model galaxies B. In the lower panel the alignment of the system and in the upper panel the corresponding rotation curves of the highlighted galaxy are shown. Here a) represents 0.5 Gyr, b) 1.7 Gyr, c) 2 Gyr, and d) 3 Gyr of evolution.
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$\begin{figure} \par\includegraphics[width=7.5cm,clip]{4976fig12.eps}\end{figure}$	Figure 12: Rotation curves for the first encounter of model galaxy A and B seen nearly edge on ( $i=80^\circ$ ) from different viewing angles. The geometry is illustrated by the image series on the left hand side. The snapshot corresponds to panel b) in Fig. 6 and therefore shows the system after 0.6 Gyr of evolution.
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$\begin{figure} \par\includegraphics[width=6.5cm,clip]{4976fig13.eps}\end{figure}$	Figure 13: Rotation curves for model galaxy A after an equal mass merger from different viewing angles. The geometry is illustrated by the image series on the left hand side. The snapshot corresponds to panel b) in Fig. 9 and therefore shows the system after 2 Gyr of evolution. The change in the sign of the velocity gradient does not appear for all viewing angles.
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