Radio relics radio emission from ltishock scenario

Radio relics are giant (Mpc) synchrotron sources that are believed to be produced by the (re)acceleration of cosmic ray electrons (CRe) by shocks in the intracluster medium. In this numerical study, we focus on the possibility that some radio relics may arise when electrons undergo diffusive shock acceleration at ltishocks in the outskirts of merging galaxy clusters. This ltishock (MS) scenario appears viable to produce CRe that emit visible synchrotron emission. We show that electrons that have been shocked ltiple times develop an energy spectrum that significantly differs from the power-law spectrum expected in the case of a single shock scenario. As a consequence, the radio emission generated by CRe that shocked ltiple times is higher than the emission produced by CRe that are shocked only once. In the case explored in this paper, the radio emission produced in the two scenarios differ by one order of magnitude. In particular in the MS scenario, the silated relic follows a KGJP spectral shape, consistent with observation. Furtheore, the produced radio emission is large enough to be detectable with current radio telescopes (e.g. LOFAR, JVLA).