Persistent Radio Sources and Multiwavelength Counterparts of Fast Radio Bursts: Magnetar Wind Nebulae and Bow Shocks in Massive Binary Systems

Abstract

Fast radio bursts (FRBs) are millisecond-duration pulses originating from cosmological distances. Multiwavelength counterparts associated with FRBs are important for unveiling their physical origins. Recent observations provide strong evidence that the sources of some active FRBs are residing in massive-star binaries. In this paper, we study the electromagnetic counterparts of FRBs, including persistent radio sources (PRSs) and multiwavelength emission from magnetar wind nebulae (MWNe) or bow shocks in massive binary systems. We find that the PRSs with luminosity 1038–1039 erg s−1 can be generated by young MWNe. The age of magnetars is a few decades. The observed long-term variation of flux density for PRSs can be explained by the internal magnetic field decay of magnetars. The bow shock radiation can account for the less luminous PRSs with luminosity ≲1036 erg s−1. Magnetically powered nebulae may yield detectable keV synchrotron self-Compton (SSC) X-rays out to ≲20 Mpc, whereas rotation-powered systems mainly produce GeV SSC emission detectable only within ≲0.1 Mpc. For active magnetars in massive binaries, enhanced wind interaction can generate synchrotron X-rays detectable within ≲50 Mpc and GeV–TeV inverse-Compton emission detectable within ≲1–0.1 Mpc.