All Figures

$\begin{figure} \par\includegraphics[width=18cm,clip]{4151f1.eps} \end{figure}$ Figure 1: Upper left panel: overview of the lens configuration. The three arcs systems {A01, A02, A2, A4}, {A1, A5} and {A'1, A6}. The central cD galaxy. This F702 HST field is $56\times 56$ arcsec wide (i.e. $180\times 180~~h^{-1}~{\rm kpc}$ ). Upper (resp. lower) right panel: reconstruction of arcs deduced from the single component best fit IS (resp. NFW) model (see 3.2). In these panels are reported the observed radial arc location. The small azimuthal offset is discussed in Sect. 4.2. The fifth demagnified image predicted by the models near the center is detailed in Fig. 4. Lower left panel, detail of some dots used for the model fitting (see Table A.1).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{H4151f2.eps} \end{figure}$ Figure 2: Orientation of the isophotal major axis as a function of radius. ( squares: intra-cluster gas, diamonds: stars in the F702 band.) The horizontal line represents the average orientation of the DM halo from modeling beyond $\sim$ $8\hbox {$^{\prime \prime }$ }$ . See Sect. 3.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4151f3.eps} \end{figure}$ Figure 3: Spectral Energy Distributions resulting from photometric redshift analysis. a) Central cD galaxy at z=0.313 and b) arc A5 deduced to be at $z\simeq 1.6$ . One can see that contrast between arcs and cD is 15 times higher in U then in a redder filter like F702.
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In the text

$\begin{figure} \par\includegraphics[width=17cm,clip]{H4151f4.eps} \end{figure}$ Figure 4: Visualization of residuals from subtraction of the cD brightness. Orientation is the same as in Fig. 1. Left panel: HST filtering. One can see the real residual as well as a simulated object derived from the IS model shown on the right panel. Note the comparable signal-to-noise. Also plotted the Mexican-hat filter size with both positive ( $r\leq 1.5~ {\rm px}$ ) and negative areas ( $1.5~ {\rm px} \leq r \leq 3.5~ {\rm px}$ ) Also shown the noise-free reconstructed 5th image of the fold arc expected from IS (middle panel) and NFW (right panel) strong lensing best fit models centered on the cD. The position is consistent with the IS model. Note that the filtering algorithm reduces the high frequencies in the upper frame. Thus, shape measurements just provide rough estimates of ellipticities, but accurate orientations. Note also that the isophote plotted here, is illustrative and does not correspond to the any quantitative shape measurement.
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In the text

$\begin{figure} \par\includegraphics[width=17cm,clip]{H4151f5.eps} \end{figure}$ Figure 5: Projected mean surface density. Solid: NFW best fit, dashed: IS. Notice how models match near the arcs locations. Between 2.5 and 28 arcsec, the mean convergences $\bar{\kappa}$ = $<\kappa >(0,r)$ differ from each other by less than 3 percents. Faint discrepancies appear in the outer regions through weak lensing signal and at the very center. Constraints due to the fifth image candidate are detailed in Sect. 3.4.3. The weak lensing data are deduced from the $\zeta _{\rm c}$ -statistic.
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In the text

$\begin{figure} \par\includegraphics[width=6.5cm,clip]{H4151f6.eps} \end{figure}$ Figure 6: Permitted potential center region ( $\Delta \chi ^2/N =1,2,3$ ) relative to the cD center (0, 0) coordinates. Solid (resp. dashed) contours refer to the NFW (resp. IS) model. The upper panel displays contours without the fifth image location knowledge and the lower using the 5th image candidate discussed in Sect. 2.5 as an additional constraint. The crosses (resp. diamonds) correspond to the $\chi ^2$ minimum location for the NFW (resp. isothermal) modeling. Note the great enhancement induced and the significant shift in the NFW case compared to the upper panel. The deflection angle is merely too small to be consistent with the fifth image.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{H4151f7.eps}\par\vspace*{2mm} \includegraphics[width=8.8cm,clip]{4151f8.eps} \end{figure}$ Figure 7: Two components $\chi ^2$ contours. Upper panel: constraints on the couple $r_{\rm c}-M/L_I$ for the IS model. Note the small modifications due to the introduction of the stellar component. Lower panel: constraints on the couple $\alpha -M/L_I$ for the pseudo-NFW family profiles. One can see an overlay of the same confidence regions when the fifth image position is known (solid) and when it is not (dashed). The inner slope $\alpha$ ranges between 0.8 and 1.1 for a reasonable mass of stars ( $\Upsilon _I \leq 5$ ). The lower panel rejects very shallow profiles ( $\alpha \leq 0.6$ ) whereas one can see on the upper one that flat cores provide good fits.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{H4151f9.eps} \end{figure}$ Figure 8: Plot of various $\zeta _{\rm c}$ curves taken along the relation plotted in blue (light gray) in Fig. 9 that give the observed critical lines. Also plotted the observed $\zeta _{\rm c}(r)$ deduced from weak lensing. Only a small scatter around $\alpha =1$ is allowed. We also report the best fit isothermal profile (dashed).
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4151f10.eps} \end{figure}$ Figure 9: Relations in the parameter space $\alpha -r_{\rm s}$ deduced from the critical lines Eq. (B.4) and Eq. (B.5) (blue or light gray region), from the $\zeta -$ statistic and Eq. (B.4) (red or dark gray) and from the radial arc length relative to its counter-image (dashed yellow area). Errors take into account variations of ellipticity, of the mass-to-light ratio and observational uncertainties. The resulting permitted region is well consistent with what is found from the modeling. One can see that $0.7\protect\la\alpha\protect\la 1.1$ . In other words, the halo density profile must be much shallower than the value 1.5 suggested by recent numerical simulations (Moore et al. 1998; Ghigna et al. 2000). The permitted range for $r_{\rm s}$ is restricted to small scale radii $r_{\rm s}\sim 100~h^{-1}~{\rm kpc}$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{H4151f11.eps}\par\vspace*{2mm} \includegraphics[width=8.8cm,clip]{H4151f12.eps} \end{figure}$ Figure C.1: Upper panel: $\chi ^2/{\rm d.o.f.}$ contour plot for the couple $(r_{\rm t*},\sigma _*)$ . The "macro'' model is the softened IS. Naturally, the $\chi ^2$ minimum ( $\sim$ 1.1) is reduced as compared to the unperturbed previous model. The three peculiar couples 1, 2, 3 predict the fifth images plotted on the lower panel. The only noticeable effect of substructures on the fifth image occurs for models with a very high $\chi ^2$ model that provide a bad fit for the external arcs.

In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{H4151f2.eps} \end{figure}$	Figure 2: Orientation of the isophotal major axis as a function of radius. ( squares: intra-cluster gas, diamonds: stars in the F702 band.) The horizontal line represents the average orientation of the DM halo from modeling beyond $\sim$ $8\hbox {$^{\prime \prime }$ }$ . See Sect. 3.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{4151f3.eps} \end{figure}$	Figure 3: Spectral Energy Distributions resulting from photometric redshift analysis. a) Central cD galaxy at z=0.313 and b) arc A5 deduced to be at $z\simeq 1.6$ . One can see that contrast between arcs and cD is 15 times higher in U then in a redder filter like F702.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{H4151f9.eps} \end{figure}$	Figure 8: Plot of various $\zeta _{\rm c}$ curves taken along the relation plotted in blue (light gray) in Fig. 9 that give the observed critical lines. Also plotted the observed $\zeta _{\rm c}(r)$ deduced from weak lensing. Only a small scatter around $\alpha =1$ is allowed. We also report the best fit isothermal profile (dashed).
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