Also, electrodynamic theory shows that the surface magnetic field on the neutron star is proportional to the square root of the product of the spin period times the period derivative. A representation of pulsars in a period derivative versus period diagram helps in the classification of pulsars according to their age and magnetic field strength. In this diagram, young, high magnetic field radio pulsars are located in the upper part. But three decades later many gamma-ray sources still defy identification. Seven gamma-ray sources near the Galactic plane have previously been identified as pulsars.
Pulsars are neutron stars formed in the collapse of massive stars in supernova explosions.
Although not yet complete, this survey is already the most successful survey for radio pulsars ever made, having found more than 600 previously unknown pulsars, nearly doubling the number previously found in 30 years of observations. The Parkes survey has found 30 radio pulsars with ages less than 100,000 years. With this encouragement the team plans to use the multibeam system to target more of these sources with even higher sensitivity and will expect to find many more gamma-ray emitting pulsars. If so, the nature of these mysterious galactic gamma-ray sources may soon be solved. Fernando Camilo is supported by NASA grant NAG 5-3229.