NATURE’S TIMEPIECE: THE EXOTIC WORLD OF PULSARS

by Dr. Andrew McCann

Neutron stars are born in the final moments of the supernova death of massive stars and, in keeping with their exotic origin, they exhibit unmatched extremes in a variety of ways. Not only are they the smallest stars we know of, neutron stars are the most dense solid objects in the known Universe. Their surface gravity is 100 billion times that of the Earth and their magnetic fields strengths, which can reach a quadrillion Gauss, are the strongest known to exist. Neutron stars are born rotating rapidly and their emission, like the beam from a lighthouse, is observed as a highly stable and regular periodic pulsation - hence the name 'pulsating star' or 'pulsar'. Although pulsars were discovered over 40 years ago and the number of known pulsars exceeds 2400, the physical processes which power the vast array of unique and often bizarre phenomena observed from pulsars are poorly understood. Explaining the observed behavior of neutron stars has become one of the most challenging puzzles in high-energy astrophysics. Despite the longstanding mystery of their emission, the steady and predictable pulsations from pulsars make them remarkably powerful astrophysical tools. This duality has put pulsars at the centre of some of the most compelling astrophysical research of the last few decades. Each week we will explore different aspects of this duality, by reviewing pulsar phenomena in different wave bands (radio, optical, x-ray, gamma-ray) and by discussing the role of pulsars in tests of Einstein's theory of relativity and in the search for gravitational waves.