Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[width=8.6cm,clip]{1523fi01.eps} \end{figure}$ Figure 1: Reliability tests of the shear estimates of objects observed in the overlapping region of the two R-band pointings. All objects with shear estimates are plotted as light dots, objects surviving our various selection criteria, detailed in the text, are plotted as crosses. Topleft: scatter plot of the $\varepsilon _1$ component estimates from the exposures centered on A 222 versus the one centered on A 223. The diagonal line is not a fit but only represents the ideal relation. Although we delete objects with corrected ellipticity $\vert\varepsilon \vert > 0.8$ from our final lensing catalog, some objects with $\vert\varepsilon \vert > 0.8$ are marked with crosses in this plot. This is because the mean ellipticity of their two measurements, which we employ in our selection and lensing analysis is below the chosen cut-off level. These objects are strongly down-weighted and their exclusion would not lead to significant differences in the lensing analysis. Top right: same for the $\varepsilon _2$ component. Bottom left: dependence of the absolute value of differences of the shear estimators $\vert\Delta \varepsilon \vert$ on the apparent magnitude of the object. As expected, fainter objects have less reliable shear estimates. Bottom right: this panels shows the correlation between $\vert\Delta \varepsilon \vert$ and the weighting scheme we employed. Objects with higher weights have more reliable shear estimates.
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In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{1523fi02.eps} \end{figure}$ Figure 2: Weak lensing surface mass density contours overlaid on the R-band mosaic observed with the Wide-Field imager at the ESO/MPG-2.2 m telescope. The shear field was smoothed with a $\sigma =1\hbox {$.\mkern -4mu^\prime $ }{75}$ Gaussian, corresponding to the diameter of the circle at the lower left corner. Each contour represents an increase in $\kappa$ of 0.005 ( $\sim$ 1.6 $\times$ $10^{13}~h_{70}~M_{\odot}$ Mpc^-2, assuming $\overline {z}_{{\rm FBG}} = 1$ ) above the mean $\kappa$ at the edge of the field.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{1523fi03.eps} \end{figure}$ Figure 3: Cumulative fraction of off-set of the reconstructed centroids from the real centroid. The curves display the probability of finding a reconstructed centroid of an SIS with a velocity dispersion of 550 km s^-1 (continuous), 700 km s^-1 (dotted), 850 km s^-1 (short dashed), 1000 km s^-1 (long dashed), and 1150 km s^-1 (dashed-dotted) from the real centroid position. The SIS was put at a redshift of z=0.21; the number density of the input catalog was 15 arcmin^-2.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.8cm,clip]{1523fi04.eps} \end{figure}$ Figure 4: Combined confidence contours for the SIS velocity dispersion of A 222 and A 223. The contour lines are drawn for $2\Delta l = \left \{ 2.3, 4.61, 6.17, 9.21, 11.8, 18.4\right \}$ , corresponding to the 63.8%, 90%, 95.4%, 99%, 99.73%, and 99.99% confidence levels, respectively, under the assumption that the statistics is approximately Gaussian.
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In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{1523fi05.eps} \end{figure}$ Figure 5: Confidence contours for the best-fit NFW parameters for A 222 (left panel) and A 223 (right panel). The contours are drawn at the same levels as in Fig. 4.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.8cm,clip]{1523fi06.eps} \end{figure}$ Figure 6: Shown above are SNR contours of the aperture mass statistics with a $6\hbox {$.\mkern -4mu^\prime $ }1$ filter radius overlaid on the WFI R-band image. The lowest contour is at 2.0, higher contours rise in steps 0.5. The mass peak $\sim$ $13\hbox {$^\prime $ }$ SE of A 222 has a peak SNR of 3.5. The circle segment in the lower left corner has the same radius as the filter function.
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In the text

$\begin{figure} \par\includegraphics[width=7.85cm,clip]{1523fi07.eps} \end{figure}$ Figure 7: Color magnitude diagram of objects around the mass peak SE of A 222. A possible red-cluster sequence can be seen around $V-R \approx 1.1$ .
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.8cm,clip]{1523fi08.eps} \end{figure}$ Figure 8: Mass and light contours in the peak SE of A 222. Black solid lines are contours of the mass reconstruction in Fig. 2, white dashed lines denote the luminosity density of galaxies with 1.0 < V - R < 1.2.
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In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{1523fi09.eps} \end{figure}$ Figure 9: Smoothed distribution of the number density ( left panel) and the luminosity density ( right panel). The smoothing was done with a $\sigma =1\hbox {$.\mkern -4mu^\prime $ }{75}$ Gaussian to match the smoothing of the weak lensing reconstruction. The diameter of the circles at the lower left corners corresponds to the FWHM of the Gaussian. The contour lines in the left panel are significance contours starting at $5 \sigma$ and rising in steps of $1 \sigma$ , the contour lines in the right panel are the surface mass density contours of the reconstruction.
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In the text

$\begin{figure} \par\includegraphics[width=12cm,clip]{1523fi10.eps} \end{figure}$ Figure 10: To the left is an overlay of X-ray contours (white lines) over the WFI images of our field. The contour lines start at $3\sigma$ and increase in steps of $2\sigma$ . All detected X-ray sources are marked; circles correspond to sources kept, while the point sources excised from the image are marked with stars. The X-ray image was smoothed with a $\sigma =1\hbox {$.\mkern -4mu^\prime $ }{75}$ Gaussian, corresponding to the diameter of the circle at the lower left corner. The black contours in the background are the significance contours of the number density from the left panel of Fig. 9.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{1523fi11.eps} \end{figure}$ Figure 11: Zoom in on the central 10 $\times$ 10 Mpc²/h₇₀² of an N-body simulation. Displayed is the projection of a slice of 2.5 Mpc/h₇₀ thickness.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.8cm,clip]{1523fi12.eps} \end{figure}$ Figure 12: Smooth density distribution of the data in the left panel from the adaptive kernel density estimate. The contours are at $\kappa = \{0.03,0.05, 0.1, 0.5\}$ .
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.8cm,clip]{1523fi13.eps} \end{figure}$ Figure 13: Reconstruction of the mass distribution in Fig. 12 on a 206 $\times$ 206 points grid. The scale of the axes is given in arcminutes. The contours mark an increase of $\kappa$ in steps of 0.025 above the mean of the edge of the field. The diameter of the circle in the lower left is equal to the FWHM of the Gaussian smoothing of the shear field.
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In the text

$\begin{figure} \par\includegraphics[width=18cm,clip]{1523fi14.eps} \end{figure}$ Figure 14: Left: fit of two NIE profiles to the simulation in Fig. 12. The contour lines increase from $\kappa = 0.025$ to $\kappa =0.25$ in steps of 0.025. Right: difference image of Fig. 12 and the left panel. The contours are at the same level as in the left panel. The filament was completely subtracted. The surface mass density in the intercluster region is mostly negative.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1523fi15.eps} \end{figure}$ Figure 15: Simple toy model of two galaxy clusters connected by a filament. A quadrupole moment is present in the aperture centered on the filament.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1523fi16.eps} \end{figure}$ Figure 16: Toy model of two galaxy clusters without a filament, illustrating why it is important to choose the correct size of the aperture.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1523fi17.eps}\end{figure}$ Figure 17: Quadrupole moment of the simulation in Fig. 12. Overlayed are the contours of the mass reconstruction in Fig. 13 and large circles with radius r₂₀₀ as determined from the 3-dimensional simulated data. |Q⁽²⁾| was computed in an aperture with radius $\theta _{{\rm max}} = 2\hbox {$^\prime $ }$ (top left), $\theta _{{\rm max}} = 3\hbox {$^\prime $ }$ (top right), $\theta _{{\rm max}} = 4\hbox {$^\prime $ }$ (bottom left), $\theta _{{\rm max}} = 5\hbox {$^\prime $ }$ (bottom right). The circles at the lower left corners have the same radii as the filter function in the respective panel. The cluster on the left has a mass of M₂₀₀ = 2.0 $\times$ $10^{14}~M_{\odot}$ , the one on the right of M₂₀₀=1.4 $\times$ $10^{14}~M_{\odot}$ .
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1523fi18.eps}\end{figure}$ Figure 18: |Q⁽²⁾| maps of toy models of two clusters. Top panel: without a connecting filament. Bottom panel: with a filament running between both clusters. Quadrupole moments in the left panel were computed in a $2\hbox {$^\prime $ }$ aperture, in the right panel in a $3\hbox {$^\prime $ }$ aperture. The radii of the apertures correspond to the radii of the circles at the lower left corners of the respective panel. White contours are surface mass density; the black circles correspond the r₂₀₀ of the clusters.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{1523fi19.eps} \end{figure}$ Figure 19: Simple model of the surface mass density distribution of an elliptical cluster and a filamentary extension along the main axis of the system. The solid line is a symmetric King profile, the long dashed line is the same King profile stretched by a factor to introduce the ellipticity seen in simulation. The filament is modeled as a separate component (dotted line). The observed profile (short dashed line) is the sum of the filament and the stretched King profile. The axes are labeled in arbitrary units. The vertical lines exemplify typical values for $\theta _{{\rm fit}}$ and $\theta _{\rm cut}$ ; see text for details.
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In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{1523fi20.eps} \end{figure}$ Figure 20: Surface mass density profiles of the cluster on the left in the reconstruction displayed in Fig. 13 along the line connecting both cluster centers. The crosses mark the surface mass density in the filament part, the dashes the surface mass density on the lefthand side of the cluster. The x-axis denotes the distance from the cluster center in arcminutes.
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In the text

$\begin{figure} \par\includegraphics[width=12cm,clip]{1523fi21.eps} \end{figure}$ Figure 21: Aperture quadrupole moment map of A 222/223 in an aperture of $3\hbox {$.\mkern -4mu^\prime $ }{2}$ radius, corresponding to the radius of the circle at the lower left corner. The thick white lines are SNR contours for |Q⁽²⁾|, the lowest contour being at 2 and higher contours increasing in steps of 0.5. The aperture quadrupole moment on the "filament'' region reaches a peak SNR of 3.0. The black lines are the contours of the mass reconstruction. The dashed circles indicate the r₂₀₀ from our best fit NFW models.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1523fi22.eps}\end{figure}$ Figure A.1: Arclet candidates around the cD galaxy in A 222. North is up and East is to the left. The scale is 10 $^{\prime \prime }$ long.

In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.8cm,clip]{1523fi04.eps} \end{figure}$	Figure 4: Combined confidence contours for the SIS velocity dispersion of A 222 and A 223. The contour lines are drawn for $2\Delta l = \left \{ 2.3, 4.61, 6.17, 9.21, 11.8, 18.4\right \}$ , corresponding to the 63.8%, 90%, 95.4%, 99%, 99.73%, and 99.99% confidence levels, respectively, under the assumption that the statistics is approximately Gaussian.
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$\begin{figure} \par\includegraphics[width=18cm,clip]{1523fi05.eps} \end{figure}$	Figure 5: Confidence contours for the best-fit NFW parameters for A 222 (left panel) and A 223 (right panel). The contours are drawn at the same levels as in Fig. 4.
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$\begin{figure} \par\includegraphics[width=7.85cm,clip]{1523fi07.eps} \end{figure}$	Figure 7: Color magnitude diagram of objects around the mass peak SE of A 222. A possible red-cluster sequence can be seen around $V-R \approx 1.1$ .
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$\begin{figure} \par\includegraphics[angle=270,width=8.8cm,clip]{1523fi08.eps} \end{figure}$	Figure 8: Mass and light contours in the peak SE of A 222. Black solid lines are contours of the mass reconstruction in Fig. 2, white dashed lines denote the luminosity density of galaxies with 1.0 < V - R < 1.2.
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$\begin{figure} \par\includegraphics[width=8.3cm,clip]{1523fi11.eps} \end{figure}$	Figure 11: Zoom in on the central 10 $\times$ 10 Mpc²/h₇₀² of an N-body simulation. Displayed is the projection of a slice of 2.5 Mpc/h₇₀ thickness.
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$\begin{figure} \par\includegraphics[angle=270,width=8.8cm,clip]{1523fi12.eps} \end{figure}$	Figure 12: Smooth density distribution of the data in the left panel from the adaptive kernel density estimate. The contours are at $\kappa = \{0.03,0.05, 0.1, 0.5\}$ .
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$\begin{figure} \par\includegraphics[angle=270,width=8.8cm,clip]{1523fi13.eps} \end{figure}$	Figure 13: Reconstruction of the mass distribution in Fig. 12 on a 206 $\times$ 206 points grid. The scale of the axes is given in arcminutes. The contours mark an increase of $\kappa$ in steps of 0.025 above the mean of the edge of the field. The diameter of the circle in the lower left is equal to the FWHM of the Gaussian smoothing of the shear field.
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$\begin{figure} \par\includegraphics[width=18cm,clip]{1523fi14.eps} \end{figure}$	Figure 14: Left: fit of two NIE profiles to the simulation in Fig. 12. The contour lines increase from $\kappa = 0.025$ to $\kappa =0.25$ in steps of 0.025. Right: difference image of Fig. 12 and the left panel. The contours are at the same level as in the left panel. The filament was completely subtracted. The surface mass density in the intercluster region is mostly negative.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1523fi15.eps} \end{figure}$	Figure 15: Simple toy model of two galaxy clusters connected by a filament. A quadrupole moment is present in the aperture centered on the filament.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{1523fi16.eps} \end{figure}$	Figure 16: Toy model of two galaxy clusters without a filament, illustrating why it is important to choose the correct size of the aperture.
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$\begin{figure} \par\includegraphics[width=8.4cm,clip]{1523fi20.eps} \end{figure}$	Figure 20: Surface mass density profiles of the cluster on the left in the reconstruction displayed in Fig. 13 along the line connecting both cluster centers. The crosses mark the surface mass density in the filament part, the dashes the surface mass density on the lefthand side of the cluster. The x-axis denotes the distance from the cluster center in arcminutes.
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