VICKY KASPI, MCGILL UNIVERSITY

PRINCETON ASTRONOMY COLLOQUIUM - FEBRUARY 24, 2004

ABSTRACT

(Anomalous) X-ray Pulsars

The "Anomalous X-ray Pulsars" (AXPs) have been mysterious for over two decades. Although these unusual objects are clearly young neutron stars, what powers their X-ray emission has been unknown. In this talk, we review the observational properties of the AXPs, namely their spin behaviour, spectra and fluxes, their pulse morphologies, their multiwavelength properties, as well as their recently discovered bursting behaviour. We contrast these properties with those of the soft gamma repeaters, a source class argued, on a variety of grounds, to be identified as "magnetars," isolated ultra-high-magnetic-field neutron stars. We show that the distinction between the two classes of object, particularly in light of AXP bursts, appears largely superficial. This clearly points to both classes being magnetars. We also discuss the issue of high-magnetic-field radio pulsars, which, according to the magnetar model, ought to produce some anomalous X-ray emission, like the AXPs.