PTF11agg AS THE FIRST EVIDENCE FOR REVERSE SHOCK EMISSION FROM A POST-MERGER MILLISECOND MAGNETAR

Based on the stiff equations of state of neutron stars (NS) and the discovery of high-mass NSs, it is highly probable that a NS-NS merger will result in a rapidly rotating massive magnetar. The central magnetar will dissipate its rotational energy to the outflow by injecting Poynting flux, which will become lepton-dominated so that a long-lasting reverse shock (RS) develops. We calculate the emission of the RS as well as the emission of forward shock (FS) and find that, in most cases, the RS emission is stronger than FS emission. It is found that the recently discovered transient, PTF11agg, can be neatly accounted for by the RS emission powered by a millisecond magnetar. Other alternative models have been considered and cannot explain the observed light curves well. We therefore suggest that PTF11agg is the first evidence for RS emission from a post-merger millisecond magnetar