Narrow Results

Currently, very long baseline interferometry technology is widely used in the astronomical measurement areas, providing about 1 $\mu$as pulsar positioning accuracy. However, these conventional methods cannot meet the higher position accuracy requirements of X-ray pulsar navigation. In this paper, we provide a novel method to measure the angular position based on X-ray intensity correlation. First, we show the relationship between the pulsar angular position and the X-ray intensity correlation. Second, we simulate the measurement error within the constraint on the photon energy fluctuations and compensation time. Finally, we propose a way to achieve such measurement. These theoretical analyses will improve the measurement accuracy of the pulsar angular position to a large extent.

Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are enigmatic pulsar-like objects. The energy budget is the fundamental problem in their studies. In the magnetar model, they are supposed to be powered by the extremely strong magnetic fields (≳ 10¹⁴G) of neutron stars. Observations for and against the magnetar model are both summarized. Considering the difficulties encountered by the magnetar model to comfortably understand more and more observations, one may doubt that AXPs and SGRs are really magnetars. If they are not magnetar candidates (including magnetar-based models), then they must be "quark star/fallback disk" systems.

A scenario for the formation of an isolated X-ray pulsar 1E161348-5055 with an anomalously long period of 6.7 hours is proposed. It is shown that this pulsar can be a descendant of a massive X-ray binary system, which disintegrated about 2000 years ago after a supernova explosion caused by the core collapse of a massive component. X-ray radiation of this object in the present epoch is generated as a result of accretion of matter onto (about 10 million years old) neutron star from the residual non-Keplerian accretion disk. The pulsar’s nebula RCW 103 is a supernova remnant formed by the explosion of its massive companion in the final evolutionary phase of a massive binary system.

Though the great progress has been understood from the multi-band observations and theoretical work since the discovery of pulsar more than fifty years ago, some basic problems are not solved, such as radiation process in pulsating ultraluminous X-ray source, the origins of fast radio burst and so on. X-ray observations could supply crucial information to understand the characteristics and behaviors of pulsars. Recently, some progress for these basic problems has been achieved via the observations of Insight-HXMT.

Though great progress has been achieved from the multi-band observations and theoretical work since the discovery of pulsars more than 50 years ago, some basic problems, such as radiation process in pulsating ultraluminous X-ray source, the origins of fast radio burst and so on. X-ray observations could supply crucial information to understand the characteristics and behaviors of pulsars. Recently, some progress for these basic problems has been achieved via the observations of Insight-HXMT.