Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[width=8cm,clip]{3675fig1.ps}\end{figure}$ Figure 1: RASS-III exposure time distribution in the analyzed area.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3675fig2.ps}\end{figure}$ Figure 2: Cumulative normalized distribution of the hardness ratio of a selection of the known clusters, galaxies and stars among the detected sources.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{3675fig3.ps}\end{figure}$ Figure 3: Cumulative normalized distributions of the spatial extent of a sample of the known stars, galaxies and clusters among all detected sources.
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In the text

$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3675fig4.ps}\end{figure}$ Figure 4: Percentage of different types of detected sources after each step of our detection and selection process.
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In the text

$\begin{figure} \par\includegraphics[width=8.4cm,clip]{3675fig5.ps}\end{figure}$ Figure 5: Comparisons, for the detected clusters, of their optical coordinates with their X-ray detection coordinates. RA and Dec are separately analyzed to check for systematic deviations.
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In the text

$\begin{figure} \par {\includegraphics[width=8.8cm,clip]{3675fig6.ps} } \end{figure}$ Figure 6: Abell 3560. Left: smoothed X-ray image with superimposed X-ray contours at 0.2 and $0.4\ {\rm counts\ px}^{-1}$ . The empty square and pentagon point to the positions of Abell 3560 and RXJ 1332.2-3303; the cross is for the location of the detection of RXJ 1332.2-3303 in this work and the circle and triangle point to the locations of the detections of Abell 3560 by Ebeling et al. (1996) and David et al. (1999). Right: optical DSS image.
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In the text

$\begin{figure} \par {\includegraphics[width=8.8cm,clip]{3675fig7.ps} } \end{figure}$ Figure 7: Histogram of the number of clusters as a function of their co-moving distance from the cluster Abell 3558. Over-plotted with a bold line is the histogram of the clusters detected in this work.
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In the text

$\begin{figure} \par {\includegraphics[width=4cm,clip]{3675f8a.eps}\hspace*{0.5cm}\includegraphics[width=3.3cm,clip]{3675f8b.eps} } \end{figure}$ Figure 8: Left and right panels: Right Ascension and Declination versus redshift for all the clusters inside the selected redshift range.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{3675fig9.eps}\end{figure}$ Figure 9: Positions of all known clusters in the area. Empty squares indicate the new detections from this work while filled circles give the positions of all other clusters.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=14.16cm]{3675f10a.eps}\par {... ...{4.2cm}\includegraphics[width=6.16cm]{3675f10b.eps}\hspace*{4.2cm}} \end{figure}$ Figure 10: Positions of all known clusters in the area inside the redshift range $0.03\leq z \leq 0.07$ . Top: RA vs. Dec; filled circles indicate clusters selected and detected in this work, empty squares represent the clusters selected during the second step analysis while empty triangles give the positions of all the optically known clusters, which have not been detected in this survey. Bottom: three-dimensional orthogonal projection; redshift is along the z axis.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{3675f11a.ps}\par\includegraphics[width=8.5cm,clip]{3675f11b.ps}\end{figure}$ Figure 11: X-ray luminosity function. Top: black points represent the binned XLF of our survey. The solid, dotted and dashed lines are the XLFs computed for the BCS, REFLEX and RASS1BS surveys. Bottom: " lower'' and " upper'' limit (see text) for the XLF of all the clusters detected in the Shapley redshift range (empty circles and filled triangles, respectively); the two dotted lines are the two best-fit results. The XLF for the central core of the SC is plotted as empty squares. The solid black line is as defined in the top panel.
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In the text

$\begin{figure} \par\mbox{\includegraphics[width=4cm]{3675f12a.ps}\hspace*{8mm}\includegraphics[width=4cm]{3675f12b.ps} } \end{figure}$ Figure 12: Left panel: bolometric X-ray luminosity versus optical luminosity. Right panel: extension of the cluster from our X-ray detection versus virial radius. Best-fit estimates are plotted as solid lines.
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In the text

$\begin{figure} \par\includegraphics[width=8.8cm,clip]{3675f13.ps}\end{figure}$ Figure 13: Cumulative mass profile of detected clusters in the Shapley redshift range (black dots). The dashed line represents the expected total mass in a homogeneous Universe of density $\rho _{\rm c}\Omega _0$ . The empty triangles are the values of the virial mass computed considering the single clusters as test particles. See Table 3 for numerical values at different radii.
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In the text

$\begin{figure} \par\includegraphics[height=6.2cm,clip]{3675fA1a.ps}\hspace*{4mm} \includegraphics[height=6.2cm,clip]{3675fA1b.ps}\end{figure}$ Figure A.1: Shown in the left panel is a half-light radius (SExtractor FLUX_RADIUS parameter) vs. R magnitude (SExtractor MAG_AUTO parameter) diagram from all detected objects in the field of B5. The bright stars are located in a narrow locus around $r_{\rm h}\approx 3.2$ . In our analysis we reject all objects in the box shown around the stellar locus and we apply an additional cut for bright galaxies (R<17). The contamination of our galaxy catalog with stars in the faint part of the stellar locus should not affect our analysis significantly. We reject bright objects to avoid the domination of our light maps by individual galaxies. Identical plots were created and examined for all fields (the cut for bright objects is always at R=17). The right panel shows B-R colors of elliptical galaxies as a function of redshift. To create the plot we used galaxy templates from Bruzual & Charlot (1993) with an exponential law (time-scale 1 Gyr) for the star formation rate. We applied the reddening law from Calzetti et al. (2000) with extinctions $A_{\rm v}=0.0$ (crosses), $A_{\rm v}=0.5$ (triangles), $A_{\rm v}=1.0$ (squares) and $A_{\rm v}=1.5$ (hexagons). Given this plot together with our B and R band data we search for Red Cluster Sequences of potential SC members in the color range 1.5<B-R<2.

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17.5cm]{3675fA2.eps}\end{figure}$ Figure A.2: Left panel: shown is the full WFI R-band field around the X-ray detection B1. RA increases to the left and Dec to the top. Black contours mark the X-ray emission linearly spaced from 0.033 to 0.017 ${\rm cts\ arcsec}^{-1}$ (in the $0.1{-}2.4\ {\rm keV}$ energy range) and white contours represent 1.5 to $4 \sigma$ (spaced by $0.5 \sigma$ ) optical light over-densities from galaxies above the background level. The light distribution is calculated on a regular grid (spacing 3 $.\mkern -4mu^\prime$ 2), where each gridpoint contains the total flux within 8 $.\mkern -4mu^\prime$ 0 weighted by a Gaussian with a width of 1 $.\mkern -4mu^\prime$ 5. Each galaxy with R>17 (see also Fig. A.1) is included and the background level and the $\sigma$ are determined from the gridpoints. The black square marks a 8 $.\mkern -4mu^\prime$ $0\times 8$ $.\mkern -4mu^\prime$ 0 region around the X-ray peak and is shown enlarged in the right panel (8 $.\mkern -4mu^\prime$ 0 corresponds to $0.46\ {\rm Mpc}$ at z=0.05). The X-ray emission is reproduced as black contours. The coordinates in the top label (given in the J2000 system) mark the location of the X-ray peak position. B1 shows a bright X-ray emission and clear light over-density is seen at the X-ray position. In the B-R color space we see an over-density of galaxies at around $B-R\approx 2.2$ (see Fig. A.13) which is very red if it originates from a galaxy cluster at $z\approx 0.05$ . We consider this case as a good candidate for a new, previously unidentified galaxy cluster.

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17.8cm]{3675fA3.eps}\end{figure}$ Figure A.3: Shown are the X-ray and light distributions around our candidate B4. See Fig. A.2 for an explanation of the elements in the figure. A clear light over-density is seen at the X-ray peak position. In the B-R color space we see indications of an over-density of galaxies at around $B-R\approx 1.6{-}1.8$ (see Fig. A.13). Hence, we consider this case as a good candidate for a new, previously unidentified galaxy cluster.

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17.8cm]{3675fA4.eps}\end{figure}$ Figure A.4: Shown are the X-ray and light distributions around our candidate B5. See Fig. A.2 for an explanation of the elements in the figure. A very strong and elongated light over-density is seen at the X-ray peak position. In the B-R color space we see a clear sequence at $B-R\approx 1.5{-}1.6$ (see Fig. A.13). In the course of our work we realized that B5 coincides with the position of the galaxy cluster Abell 3538 (marked with a cross in the plots). In in this figure, the 8 $.\mkern -4mu^\prime$ $0\times 8$ $.\mkern -4mu^\prime$ 0 cutout is centered around the coordinates of the Abell cluster. There is no measured redshift for it in the literature.

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17.8cm]{3675fA5.eps}\end{figure}$ Figure A.5: Shown are the X-ray and light distributions around our candidate B6. See Fig. A.2 for an explanation of the elements in the figure. B6 has a bright X-ray emission and the primary peak seems to originate from the QSO HE1256-2139 (z=0.146) at 12:59:02.4; -21:55:38 (J2000) whose position is marked with a circle. However, the X-ray emission is elongated in the east-west direction and we identify a strong light over-density around 12:59:29.86; -21:52:07.4 (J2000) within the X-ray emission area. In the B-R plot we also see indications for a sequence at around $B-R\approx 1.5{-}1.7$ (see Fig. A.13). We checked that the sequence does not become more prominent if we include more galaxies to the north-east of the light over-density. We consider B6 as a good candidate for a new, hitherto unidentified galaxy cluster.

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17.8cm]{3675fA6.eps}\end{figure}$ Figure A.6: Shown are the X-ray and light distributions around our candidate B7. See Fig. A.2 for an explanation of the elements in the figure. B7 shows a double peak X-ray emission that is probably the superposition of the distributions from the QSO RBS1291 (z=0.25) at 13:35:29.7s; -29:50:39s (J2000) and the bright variable star V347 Hya at 13:34:57.40; -29:55:24.0 (J2000). Both point sources are marked with a circle. We see only very slight light over-densities within the X-ray emission and no signs of a sequence in the B-R diagram (see Fig. A.14). Hence, we consider the presence of a new Shapley member in this field as very unlikely.

In the text

$\begin{figure} \par {\includegraphics[angle=-90,width=17.8cm]{3675fA7.eps} } \end{figure}$ Figure A.7: Shown are the X-ray and light distributions around our candidate B8. See Fig. A.2 for an explanation of the elements in the figure. B8 shows a bright, extremely diffuse X-ray emission. We identified several bright galaxies with measured redshifts between 0.0097 and 0.0116 which are marked with circles. Hence, the X-ray flux most probably originates from a galaxy group at $z\approx 0.01$ . We see a slight light over-density very close to the X-ray peak but no trends in the B-R diagram although many bright galaxies populate the region between 1.5<B-R<2 (see Fig. A.14). Hence, we consider this case as uncertain. We note that the X-ray peak position is listed as cluster candidate (RXCJ1304.2-3030) within the REFLEX sample; see Böhringer et al. (2004).

In the text

$\begin{figure} \par\includegraphics[angle=-90,width=17.8cm]{3675fA8.eps}\end{figure}$ Figure A.8: Shown are the X-ray and light distributions around our candidate B9. See Fig. A.2 for an explanation of the elements in the figure. B9 shows a bright X-ray emission. Probably the only source for the observed X-ray emission is the bright star close to the X-ray peak. We see slight galaxy over-densities within the emission area and no signs for galaxy concentrations in the B-R plot (see Fig. A.14). Hence, we consider it unlikely that a Shapley member contributes to the X-ray flux in this field.

In the text

$\begin{figure} \par {\includegraphics[angle=-90,width=17.8cm]{3675fA9.eps} } \end{figure}$ Figure A.9: Shown are the X-ray and light distributions around our candidate B11. See Fig. A.2 for an explanation of the elements in the figure. B11 is a field with a high stellar density which significantly hampers the optical search for galaxy over-densities. We see no indications for the possible presence of a galaxy cluster in the light or color (B-R) distributions (see also Fig. A.14). The most probable explanation for the X-ray emission is the superposition of point sources.

In the text

$\begin{figure} \par {\includegraphics[angle=-90,width=17.8cm]{3675fA10.eps} } \end{figure}$ Figure A.10: Shown are the X-ray and light distributions around our candidate B12. See Fig. A.2 for an explanation of the elements in the figure. B12 shows a bright an extended X-ray emission. The case of B12 also lies within a stellar field as B11 and our conclusions are the same as for that field.

In the text

$\begin{figure} \par {\includegraphics[angle=-90,width=17.8cm]{3675fA11.eps} } \end{figure}$ Figure A.11: Shown are the X-ray and light distributions around our candidate B13. See Fig. A.2 for an explanation of the elements in the figure. B8 shows an extended X-ray emission. The case of B13 lies within a stellar field as B11 and our conclusions are the same as for that field.

In the text

$\begin{figure} \par {\includegraphics[angle=-90,width=17.8cm]{3675fA12.eps} } \end{figure}$ Figure A.12: Shown are the X-ray and light distributions around our candidate B14. See Fig. A.2 for an explanation of the elements in the figure. B14 shows an elongated X-ray emission. Similar to B11, B12 and B13 the location within a stellar field makes a quantitative analysis in the optical difficult. Because of the good X-ray detection and an extended over-density directly at the X-ray peak we classify this case as uncertain. No indications for a cluster sequence are seen in the B-R diagram; see Fig. A.15.

In the text

$\begin{figure} \par {\includegraphics[width=17.8cm]{3675fA13.ps} } \end{figure}$ Figure A.13: Shown are color-magnitude diagrams for our candidates B1, B4, B5 and B6. Dots represent all galaxies within the corresponding WFI fields. Filled triangles represent the galaxies in a 8 $.\mkern -4mu^\prime$ $0\times 8$ $.\mkern -4mu^\prime$ 0 around the X-ray peak positions (see Figs. A.2-A.5). For rich galaxy clusters at $z\approx 0.05$ we would expect a Red-Cluster Sequence from elliptical galaxies around 1.5<B-R<2 (see also Fig. A.1).

In the text

$\begin{figure} \par {\includegraphics[width=17.8cm]{3675fA14.ps} } \end{figure}$ Figure A.14: Shown are color-magnitude diagrams for our candidates B7, B8, B9 and B11. For an explanation of the plot see the caption from Fig. A.13.

In the text

$\begin{figure} \par {\includegraphics[width=17.8cm]{3675fA15.ps} } \end{figure}$ Figure A.15: Shown are color-magnitude diagrams for our candidates B7, B8, B9 and B11. For an explanation of the plot see the caption from Fig. A.13.

In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{3675fig1.ps}\end{figure}$	Figure 1: RASS-III exposure time distribution in the analyzed area.
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$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3675fig2.ps}\end{figure}$	Figure 2: Cumulative normalized distribution of the hardness ratio of a selection of the known clusters, galaxies and stars among the detected sources.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{3675fig3.ps}\end{figure}$	Figure 3: Cumulative normalized distributions of the spatial extent of a sample of the known stars, galaxies and clusters among all detected sources.
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$\begin{figure} \par\includegraphics[width=7.8cm,clip]{3675fig4.ps}\end{figure}$	Figure 4: Percentage of different types of detected sources after each step of our detection and selection process.
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$\begin{figure} \par\includegraphics[width=8.4cm,clip]{3675fig5.ps}\end{figure}$	Figure 5: Comparisons, for the detected clusters, of their optical coordinates with their X-ray detection coordinates. RA and Dec are separately analyzed to check for systematic deviations.
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$\begin{figure} \par {\includegraphics[width=8.8cm,clip]{3675fig7.ps} } \end{figure}$	Figure 7: Histogram of the number of clusters as a function of their co-moving distance from the cluster Abell 3558. Over-plotted with a bold line is the histogram of the clusters detected in this work.
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$\begin{figure} \par {\includegraphics[width=4cm,clip]{3675f8a.eps}\hspace*{0.5cm}\includegraphics[width=3.3cm,clip]{3675f8b.eps} } \end{figure}$	Figure 8: Left and right panels: Right Ascension and Declination versus redshift for all the clusters inside the selected redshift range.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{3675fig9.eps}\end{figure}$	Figure 9: Positions of all known clusters in the area. Empty squares indicate the new detections from this work while filled circles give the positions of all other clusters.
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$\begin{figure} \par\mbox{\includegraphics[width=4cm]{3675f12a.ps}\hspace*{8mm}\includegraphics[width=4cm]{3675f12b.ps} } \end{figure}$	Figure 12: Left panel: bolometric X-ray luminosity versus optical luminosity. Right panel: extension of the cluster from our X-ray detection versus virial radius. Best-fit estimates are plotted as solid lines.
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$\begin{figure} \par\includegraphics[width=8.8cm,clip]{3675f13.ps}\end{figure}$	Figure 13: Cumulative mass profile of detected clusters in the Shapley redshift range (black dots). The dashed line represents the expected total mass in a homogeneous Universe of density $\rho _{\rm c}\Omega _0$ . The empty triangles are the values of the virial mass computed considering the single clusters as test particles. See Table 3 for numerical values at different radii.
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