Astronomy & Astrophysics

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$\begin{figure} \par\includegraphics[width=7.6cm,clip]{4096_fig1.ps}\end{figure}$ Figure 1: Evolution of $\gamma _{\rm b}$ inside the cooling flow region for two different cases of re-acceleration: $\alpha _+$ given by Fermi-like processes related to the MHD turbulence in the cooling flow (bold line; Eq. (4) for typical values of the parameters), and $\alpha _+$ = constant (dashed line).
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip,angle=-90]{4096_fig2.ps}\end{figure}$ Figure 2: Left panel: 327 MHz map of the mini-halo in the Perseus cluster at a resolution of $51'' \times 77''$ (Sijbring 1993). The cross indicates the position of the cD galaxy NGC 1275 and the dashed line represents the direction considered for the application of GBS's model. Right panel: X-ray (grey scale)/radio (contours) overlay for the central part of the Perseus cluster around NCG 1275 (Fabian et al. 2000); X-ray data are obtained with Chandra.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4096_fig3.ps}\end{figure}$ Figure 3: 1.5 GHz VLA map of A2626 at a resolution of $17'' \times 17''$ . The contour levels are -0.06 (dashed), 0.06, 0.12, 0.24, 0.48, 0.96, 1.92, 2.5, 4, 8, 10, 12 mJy/beam. The rms noise is 0.02 mJy/beam. The cross indicates the position of the cluster center.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4096_fig4.ps}\end{figure}$ Figure 4: 330 MHz VLA map of A2626 at a resolution of $17'' \times 17''$ . The contour levels are -8.5 (dashed), 8.5, 17, 34, 68, 100, 135, 160 mJy/beam. The rms noise is 3.1 mJy/beam. The cross indicates the position of the cluster center and the dashed region defines the central brightness hole.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{4096_fig5.ps}\end{figure}$ Figure 5: 1.5 GHz VLA map of A2626 at a resolution of $4.5''~ \times~ 3.9''$ . The contour levels are -0.09 (dashed), 0.09, 0.18, 0.36, 0.7, 1.4, 3, 5.5, 11, 20 mJy/beam. The rms noise is 0.03 mJy/beam.
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In the text

$\begin{figure} \par\includegraphics[angle=180,width=7.3cm,clip]{4096_fig6.ps}\end{figure}$ Figure 6: 1.5 GHz VLA map of A2626 at a resolution of $17'' \times 17''$ after the subtraction of the two elongated features visible in Fig. 5. The cross indicates the position of the cluster center. The contour levels are -0.18 (dashed), 0.18, 0.36, 0.72, 1.2, 1.85, 2.3 mJy/beam. The rms noise is 0.08 mJy/beam. The dash-dotted circle defines the nuclear region excluded in modelling the diffuse radio emission, while the solid line represents the direction we have considered for the surface brightness profile (see Fig. 8).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7.1cm,clip]{4096_fig7.ps}\end{figure}$ Figure 7: Spectral index distribution between $\nu =330$ MHz and $\nu = 1.5$ GHz at a resolution of $17'' \times 17''$ . The contours are in steps of 0.2, where the lightest grey is in the range 2.8 to 3. The lighter the grey, the steeper the spectral index. We have excluded the region in which the error is >0.2. The cross indicates the position of the subtracted radio core and the solid line represents the direction we have considered for the spectral steepening profile (see Fig. 10).
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In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{4096_fig8.ps}\end{figure}$ Figure 8: Fit to the surface brightness profile (black circles) observed at 1.5 GHz along the radial direction indicated in Fig. 6. The dotted line defines the observed region of values of the brightness distribution at any radius, while the large dashed line represents the 2 rms noise level of the map subtracted from the elongated radio features (the errorbars are at 1 $\sigma$ ). The fit is obtained with the following set of parameters: $B_{\rm c}=1.5~\mu\mbox{G}$ , $l_{\rm c}=175 \mbox{ pc}$ , s=-0.5. For comparison, we also report (with triangles) the brightness profile taken along the same radial direction from the 1.5 GHz map including the contribution of the elongated features (Fig. 3). The small dashed line represents the 2 rms noise level of the non-subtracted map.
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{4096_fig9.ps}\end{figure}$ Figure 9: Fit to the total spectrum of the synchrotron emission obtained with the same set of parameters of Fig. 8. The flux densities observed at 330 MHz and 1.5 GHz are taken from Table 2, while the flux density at 609 MHz is obtained by subtracting the estimated core emission from the total flux given by Roland et al. (1985). The contribution of the elongated features to the flux of the diffuse emission (as estimated in Sect. 3.1) is included in the errorbars.
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{4096_fig10.ps}\end{figure}$ Figure 10: Fit to the radial spectral steepening between $\nu =330$ MHz and $\nu = 1.5$ GHz obtained with the same set of parameters of Fig. 8. The data are taken from the spectral index distribution along the direction indicated in Fig. 7. The effect induced by the contribution of the elongated features to the flux of the diffuse emission (as estimated in Sect. 3.1) is included in the errorbars.
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In the text

$\begin{figure} \par\includegraphics[width=7.7cm,clip]{4096_fig11.ps}\end{figure}$ Figure 11: Integrated radio power at 1.4 GHz, $\left [ \nu P_{\nu } \right ]_{\rm 1.4 GHz}$ , vs. cooling flow power, $P_{\rm CF} = \dot{M} k T/\mu m_{\rm p}$ , for the mini-halo clusters in Table 5.
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{4096_fig1.ps}\end{figure}$	Figure 1: Evolution of $\gamma _{\rm b}$ inside the cooling flow region for two different cases of re-acceleration: $\alpha _+$ given by Fermi-like processes related to the MHD turbulence in the cooling flow (bold line; Eq. (4) for typical values of the parameters), and $\alpha _+$ = constant (dashed line).
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$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4096_fig3.ps}\end{figure}$	Figure 3: 1.5 GHz VLA map of A2626 at a resolution of $17'' \times 17''$ . The contour levels are -0.06 (dashed), 0.06, 0.12, 0.24, 0.48, 0.96, 1.92, 2.5, 4, 8, 10, 12 mJy/beam. The rms noise is 0.02 mJy/beam. The cross indicates the position of the cluster center.
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$\begin{figure} \par\includegraphics[angle=-90,width=7.5cm,clip]{4096_fig4.ps}\end{figure}$	Figure 4: 330 MHz VLA map of A2626 at a resolution of $17'' \times 17''$ . The contour levels are -8.5 (dashed), 8.5, 17, 34, 68, 100, 135, 160 mJy/beam. The rms noise is 3.1 mJy/beam. The cross indicates the position of the cluster center and the dashed region defines the central brightness hole.
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$\begin{figure} \par\includegraphics[width=7.5cm,clip]{4096_fig5.ps}\end{figure}$	Figure 5: 1.5 GHz VLA map of A2626 at a resolution of $4.5''~ \times~ 3.9''$ . The contour levels are -0.09 (dashed), 0.09, 0.18, 0.36, 0.7, 1.4, 3, 5.5, 11, 20 mJy/beam. The rms noise is 0.03 mJy/beam.
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$\begin{figure} \par\includegraphics[width=7.7cm,clip]{4096_fig11.ps}\end{figure}$	Figure 11: Integrated radio power at 1.4 GHz, $\left [ \nu P_{\nu } \right ]_{\rm 1.4 GHz}$ , vs. cooling flow power, $P_{\rm CF} = \dot{M} k T/\mu m_{\rm p}$ , for the mini-halo clusters in Table 5.
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