MULTI-MESSENGER TESTS FOR FAST-SPINNING NEWBORN PULSARS EMBEDDED IN STRIPPED-ENVELOPE SUPERNOVAE

Fast-spinning strongly magnetized newborn neutron stars (NSs), including nascent magnetars, are popularly implemented as the engine of luminous stellar explosions. Here, we consider the scenario that they power various stripped-envelope (SE) supernovae (SNe), not only superluminous SNe Ic but also broad-line (BL) SNe Ibc and possibly some ordinary SNe Ibc. This scenario is also motivated by the hypothesis that Galactic magnetars largely originate from fast-spinning NSs as remnants of SE SNe. By consistently modeling the energy injection from magnetized wind and ⁵⁶Ni decay, we show that proto-NSs with ≳10 ms rotation and a poloidal magnetic field of B_dip ≳ 5 × 10¹⁴ G can be harbored in ordinary SNe Ibc. On the other hand, millisecond proto-NSs can solely power BL SNe Ibc if they are born with B_dip ≳ 5 × 10¹⁴ G and superluminous SNe Ic with B_dip ≳ 10¹³ G. Then, we study how multi-messenger emission can be used to discriminate such pulsar-driven SN models from other competitive scenarios. First, high-energy X-ray and gamma-ray emission from embryonic pulsar wind nebulae can probe the underlying newborn pulsar. Follow-up observations of SE SNe using NuSTAR∼50-100 after the explosion are strongly encouraged for nearby objects. We also discuss possible effects of gravitational waves (GWs) on the spin-down of proto-NSs. If millisecond proto-NSs with B_dip < a few × 10¹³ G emit GWs through, e.g., non-axisymmetric rotation deformed by the inner toroidal fields of B_t ≳ 10⁶ G, the GW signal can be detectable from ordinary SNe Ibc in the Virgo cluster by Advanced LIGO, Advanced Virgo, and KAGRA.