Pulse Period History and Phase Resolved Spectra of 1A 0535+262

TL;DR

This paper analyzes the long-term pulse period history, energy-dependent pulse profiles, and phase-resolved spectra of the Be/X-ray binary 1A 0535+262 using INTEGRAL and RXTE data, covering its recent outbursts after 11 years of quiescence.

Contribution

It provides new insights into the pulse period evolution and spectral characteristics of 1A 0535+262 during its recent outbursts, utilizing recent observational data.

Findings

Long-term pulse period history analyzed

Energy-dependent pulse profiles characterized

Phase-resolved spectra obtained

Abstract

The Be/X-ray binary 1A 0535+262 was discovered in 1975 during a giant outburst. Afterwards it has shown periods of quiescence (flux below 10 mCrab), normal outbursts (10 mCrab-1Crab) and occasionally giant outbursts (several Crab). Ending 11 years of quiescence, the last giant outburst took place in May/June 2005, but the source was too close to the Sun to be observed by most satellites. A subsequent normal outburst took place in August 2005, which was observed by INTEGRAL and RXTE TOO observations. Based on INTEGRAL data, we present results on the long term pulse period history of the source, on their energy dependent pulse profiles and on phase resolved spectra.