Possible Dates of Birth of Pulsars from Ancient Chinese Records

Abstract

THE pulsar NP 0532 has been identified with the central star of the Crab Nebula¹, the famous remnant of the “Chinese” supernova of 1054. There is thus a prima facie case for a systematic search through ancient Chinese records for similar coincidences. The following argument can be put forward against this undertaking. The pulsar NP 0532 has by far the shortest known period and, further, its period is increasing². If all pulsars begin their existence with about the same period and if the period always increases secularly, then the much longer periods of the other pulsars imply that they were formed long before historical times. But this argument is, of course, based on only one single instance. If the radio sources OON 6A and CTB 41 associated respectively with Tycho's supernova of 1572 and Kepler's of 1604 are indeed pulsars with periods even shorter than that of NP 0532, then the argument would be compelling, but, as things are, it is better to adopt a more flexible stand and assume that the period of a pulsar is not a function of its age only and that at least some of the other known pulsars could have been formed within the last two or three thousand years.