Transient Phenomena in Anomalous X-ray Pulsars

TL;DR

This paper reviews recent observations of transient phenomena in two anomalous X-ray pulsars, highlighting their outburst behaviors, spectral and timing properties, and the insights gained from multi-wavelength monitoring.

Contribution

It provides new observational data and analysis of outburst events in AXPs, emphasizing the importance of simultaneous X-ray and radio observations for understanding their transient behavior.

Findings

XTE J1810-197 shows unique cooling and fading properties.

CXOU J164710.2-455216's outburst monitored from onset, revealing early spectral and timing evolution.

Multi-wavelength observations are crucial for studying transient AXPs.

Abstract

In 2003 a previously unpulsed Einstein and ROSAT source cataloged as soft and dim (Lx of few 10^33 ergs) thermal emitting object, namely XTE J1810-197, was identified as the first unambiguous transient Anomalous X-ray Pulsar. Two years later this source was also found to be a bright highly polarized transient radio pulsar, a unique property among both AXPs and radio pulsars. In September 2006 the Swift Burst Alert Telescope (BAT) detected an intense burst from the candidate AXP CXOU J164710.2-455216, which entered in an outburst state reaching a peak emission of at least a factor of 300 higher than quiescence. Here, we briefly outline the recent results concerning the outburst phenomena observed in these two AXPs. In particular, XTE J1810-197 has probed to be a unique laboratory to monitor the timing and spectral properties of a cooling/fading AXP, while new important information have been inferred from X-ray and radio band simultaneous observations. CXOU J164710.2-455216 has been monitored in X-rays and radio bands since the very beginning of its outbursting state allowing us to cover the first phases of the outburst and to study the timing and spectral behavior during the first months.