Proto–Neutron Star Winds with Magnetic Fields and Rotation

We solve the 1D neutrino-heated non-relativistic MHD wind problem forconditions that range from slowly rotating (spin period P > 10 ms) protoneutronstars (PNSs) with surface field strengths typical of radio pulsars (B < 10^13G), to "proto-magnetars" with B ~ 10^14-10^15 G in their hypothesized rapidlyrotating initial states (P ~ 1 ms). We use the simulations of Bucciantini etal. (2006) to map our monopole results onto a more physical dipole geometry andto estimate the spindown of PNSs when their winds are relativistic. We thenquantify the effects of rotation and magnetic fields on the mass loss, energyloss, and r-process nucleosynthesis in PNS winds. We describe the evolution ofPNS winds through the Kelvin-Helmholtz cooling epoch, emphasizing thetransition between (1) thermal neutrino-driven, (2) non-relativisticmagnetically-dominated, and (3) relativistic magnetically-dominated outflows.We find that proto-magnetars with P ~ 1 ms and B > 10^15 G drive relativisticwinds with luminosities, energies, and Lorentz factors (magnetization sigma ~0.1-1000) consistent with those required to produce long duration gamma-raybursts and hyper-energetic supernovae (SNe). A significant fraction of therotational energy may be extracted in only a few seconds, sufficiently rapidlyto alter the asymptotic energy of the SN remnant, its morphology, and,potentially, its nucleosynthetic yield. Winds from PNSs with more modestrotation periods (2 - 10 ms) and with magnetar-strength fields produceconditions significantly more favorable for the r-process than winds fromslowly rotating PNSs. Lastly, we show that energy and momentum deposition byconvectively-excited waves further increase the likelihood of successfulr-process in PNS winds.Comment: 21 pages, 12 figures, final version accepted to Ap