Relativistic Shock Propagation and Search for Electromagnetic Pulses from Supernovae

An electromagnetic pulse from a supernova occurring within its own magnetic field was previously predicted. We have searched for such pulses and continued theoretical investigations of the relativistic shock strength in a supernova envelope. The relativistic equations were differenced in characteristic form by using an energy Lagrange frame to calculate the shock and a mass Lagrange frame for the subsequent vacuum blowoff. The results are consistent with analytical solutions and show that the shock energy factor , .l32 F-o ' , where p = density and F = polytropic mass fraction ahead of the shock. The final expansion increases the kinetic energy factor to F-o o, which results in a cosmic-ray spectrum N(>E) 2.5 The shock energy factor is now 70 at breakout (a 1 g surface layer), which is a factor of 30 less than previously estimated. The expected signal from a supernova at 100 Mpc is reduced from l0 kT to kT for an antenna gain of 4ir. We have searched for dispersed pulses (0.1 to 100 5 per e-fold in frequency) with a phase-locked loop detector at 4 X 108 Hz, input noise 10 kT 3 steradian antenna, and with a frequency tracking receiver at 1.4 X 10 Hz, 1 kT noise and ` steradian antenna for 10 nights, each with negative results. These null results are consistent with theory.