Letter to the Editor

An accretion disk model for periodic timing variations of pulsars

Department of Astronomy, School of Physics, Peking University, Beijing 100871, PR China e-mail: bxyq@vega.bac.pku.edu.cn

Corresponding author: G. J. Qiao, gjn@pku.edu.cn

Received: 12 March 2003
Accepted: 23 June 2003

Abstract

The long-term, highly periodic and correlated variations in both the pulse shape and the rate of slow-down of two isolated pulsars (PSRs) PSR B1828-11 and PSR B1642-03 were discovered recently. This phenomenon may provide evidence for “free precession” as suggested in the literature. Some authors presented various kinds of models to explain this phenomenon within the framework of free precession. Here we present an accretion disk model for this precession phenomenon instead. Under reasonable parameters, the observed phenomenon can be explained by an isolated pulsar with a fossil disk. This may link radio pulsars and anomalous X-ray pulsars (AXPs) and present an indirect evidence for the existence of the fossil disk in nature.