Pulsed 10–30 MeV gamma rays from PSR0833-45

Abstract

OF the more than 100 known pulsars the one in Vela, PSR0833-45 is the most like the Crab pulsar in many of its characteristics. It has the second shortest period (89 ms), the second largest dP/dt, undergoes sudden ‘glitches’ or decreases in its period¹ and is associated with a known supernova remnant². The many optical searches for pulsed radiation have so far been negative³. In the X-ray region a positive result was reported for 0.5 to 1.5 keV but 29 ms earlier in phase than the radio frequency pulse⁴. At 23 to 80 keV evidence was found for pulsed emission with a period 155 ns different from the radio period⁵. Later X-ray observations have not detected any pulsed radiation^6–8. Observations from Uhuru show an X-ray source at this position⁹, but the time resolution was too long to detect pulsing. Grindlay et al.¹⁰ have reported a possible indication of pulsed emission above 3 × 10¹¹ eV.