JVLA and Chandra observations of the HST Frontier Cluster MACS J0717.5+3745

Massive clusters, particularly merging clusters with multiple superposed subhalos, are powerful cosmic telescopes, capable of magnifying high-z galaxies, thus providing a probe of the high-z Universe. In addition, merging clusters are excellent laboratories to investigate how the particles that produce cluster-scale diffuse radio emission are accelerated.We present Chandra and JVLA observations of the HST Frontier Cluster MACS J0717.5+3745. MACS J0717.5+3745 is the largest known cosmic lens,making it a promising target to search for lensed radio and X-ray sources. With the high-resolution 1.0-6.5 GHz JVLA imaging, we find a total of 8 lensed sources with amplification factors larger than 2. Two of these lensed sources are also detected in the Chandra images. The majority of the lensed sources are likely star forming galaxies with star formation rates of 10-20 Msun/year. Our observations indicate that deep radio imaging of galaxy clusters, in combination with optical and lensing data, can be used to study the faint radio source population which would otherwise only be possible with the The Square Kilometre Array.Our radio images also show the presence of a peculiar 700 kpc elongated diffuse radio source in the cluster. Chandra detects hot gas with a temperature of ~20 keV at the location of the radio source. This suggests that the radio emission traces a large shock-heated region in the cluster, where fossil particles from a tailed radio galaxy have been re-accelerated.