tokens: of the ejecta, the luminosity of this radioactivity-powered AIC optical emission cannot be much higher than ∼10 41 erg s −1 , even though the synthesization of 56 Ni in the ejecta is very efficient. In principle, the AIC NSs could sometimes (but may not always) be converted into magnetars, as these NSs can initially rotate very rapidly and differentially. Following this consideration, it has been suggested that the rapid spin-down of the magnetars can substantially affect the AIC optical transient, e.g., by providing an extra energy source to heat the AIC ejecta (Yu et al. 2015 , 2019 ). In more detail, the energy released from the magnetars can be initially in the form of a Poynting flux, which could eventually transform into a relativistic electron-positron wind. Then, questions arise as to what kind of emission can be produced by the pulsar wind (PW) and how energy is transferred from the PW to the AIC ejecta. It is expected that the PW emission, if detected, can help to identify AIC candidates in the future. Basically, PW emission could be mainly determined by the collisions of the PW with the AIC ejecta and, in particular, with the companion star. An illustration of these interactions is presented in Figure 1 . Considering the fact that the spin-down luminosity of a magnetar can be as high as ∼10 45 erg s −1 , the companion could be completely evaporated by the PW in a few days, because the gravitational binding energy of the companion is probably not much higher than ∼10 48 erg. The evaporated companion material (ECM) would finally form a torus due to the orbital motion, which surrounds the magnetar and blocks the PW in the orbital plane. The formation of such an ECM torus and its interaction with the PW are investigated in Section 2 . Meanwhile, the termination shock (TS) of the PW due to its interaction with the AIC ejecta is calculated in Section 3 . Both of these PW emission components can penetrate the AIC ejecta and become detectable as long as the ejecta becomes transparent for X-rays. A summary of our calculations is given in Section 4 . In Section 5 , we discuss the possible application of the AIC model in explaining the multi-wavelength emission of a recently discovered fast-evolving luminous optical transient: AT 2018cow. Figure 1. Illustration of a post-AIC system (not to scale), including the stages before and after the breakdown of an ECM torus. 2. The Interaction of a PW with a Companion 2.1. The Evaporation of a Companion Some NSs formed from AIC events are considered to rotate very rapidly and possibly differentially. In this case, the magnetic fields of the NSs can be significantly amplified through magnetorotational instability (Duncan Thompson 1992 ; Dessart et al. 2007 ; Cheng Yu 2014 ). However, in practice, it is still difficult to assign a fiducial value to the spin periods and the magnetic fields of the NSs, because these parameter values are highly dependent on the properties of progenitor WDs. In principle,
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