Detailed high-energy characteristics of AXP 1RXS J170849-400910 - Probing the magnetosphere using INTEGRAL, RXTE and XMM-Newton

TL;DR

This study provides a comprehensive analysis of the spectral and temporal X-ray characteristics of AXP 1RXS J170849-400910 using data from INTEGRAL, RXTE, and XMM-Newton, revealing complex pulse components and phase-dependent spectral changes.

Contribution

It offers the first detailed phase-resolved spectroscopy of this AXP, identifying three distinct spectral components with unique pulse profiles and stability over time.

Findings

The hard X-ray spectrum extends up to ~175 keV with no spectral break.

Pulsed emission is detected up to 270 keV with high significance.

Three distinct pulse components with different spectral shapes and phase distributions are identified.

Abstract

We present detailed spectral and temporal characteristics over the whole X-ray band. For this purpose data have been used from INTEGRAL, RXTE and XMM-Newton. The INTEGRAL hard X-ray (>10 keV) time-averaged total spectrum, can be described by a power law with a photon index Gamma = 1.13 +/- 0.06 and extends to ~175 keV. No evidence for a spectral break is found. No significant long-term time variability has been detected above 20 keV. Pulsed emission is measured up to 270 keV (12.3 sigma; 20-270 keV). Three different pulse components can be recognized in the pulse profiles: 1) a hard pulse which contributes above ~4 keV, 2) a softer pulse not contributing in the hard X-ray domain and 3) a very soft pulse component below 2 keV. Detailed phase-resolved spectroscopy of the pulsed emission confirms long-term stability. The spectral shape gradually changes with phase from a soft single power law to a complex multi-component shape and then to a hard single power law. The spectrum switches from a very hard (Gamma = 0.99 +/- 0.05) to a very soft (Gamma = 3.58 +/- 0.34) single power-law shape within a 0.1-wide phase interval. We identify three independent components. The three shapes are a soft power law, a hard power law and a curved shape. The phase distributions of the normalizations of these spectral components form three decoupled pulse profiles. The soft component peaks around phase 0.4 while the other two components peak around phase 0.8. The width of the curved component (~0.25 in phase) is about half the width of the hard component.