A rapidly rotating neutron star with strong magnetic fields, called magnetar, is a possible candidate for the central engine of long gamma-ray bursts and hypernovae (HNe). We solve the evolution of a shock wave driven by the wind from magnetar and evaluate the temperature evolution, by which we estimate the amount of $^{56}$Ni that produces a bright emission of HNe. We obtain a constraint on the magnetar parameters, namely the poloidal magnetic field strength ($B_p$) and initial angular velocity ($Omega_i$), for synthesizing enough $^{56}$Ni mass to explain HNe ($M_{^{56}mathrm{Ni}}gtrsim 0.2M_odot$), i.e. $(B_p/10^{16}~mathrm{G})^{1/2}(Omega_i/10^4~mathrm{rad~s}^{-1})gtrsim 0.7$.
تحميل البحث