In the example cooling flow clusters with central radio sources described above, there is either a clear correlation between the radio data and the X-ray emission, such that the radio emission fills the bubbles in the X-ray, or the bubbles are completely devoid of (high frequency) radio emission (the ghost cavities). In addition to these examples, there also exist intermediate cases, "missing links" as suggested by Heinz et al. 2002, where the radio emission partly fills the holes seen in the X-ray. In these cases, it is possible that the radio emission that previously filled the cavities has faded, due to synchrotron losses of the relativistic electrons. Good examples of these intermediate cases are Abell 4059 (Fig. 13, Heinz et al. 2002) and Abell 478 (Fig. 14, Sun et al. 2003).
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Figure 13. Adaptively-smoothed Chandra image of the cooling flow cluster Abell 4059. Contours of the 8 GHz radio emission are superposed. The radio emission only partly fills the cavities in the X-ray (Heinz et al. 2002). |
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Figure 14. Adaptively-smoothed Chandra image of the cooling flow cluster Abell 478, with contours of the 1.4 GHz radio emission overlaid. This is a similar case to that of Abell 4059, where the radio emission only partly fills the X-ray holes (Sun et al. 2003). |