Phase-dependent Evolution within the Large Luminosity Range of 1A 0535+262 Observed by Insight-HXMT during 2020 Giant Outburst
Abstract
We have performed phase-resolved spectral analysis of the accreting pulsar 1A 0535+262 based on observations of Insight-HXMT during the 2020 type II outburst of the source. We focus on the two-dimensional dependence of the cyclotron resonance scattering features (CRSFs) along the outburst time and at different phases. The fundamental CRSF line (f-CRSF) shows different time- and phase-dependent behaviors. At higher luminosity, the phase profile of the f-CRSF energy changes from a single peak to double peaks, with the transition occurring at MJD 59185. On the contrary, the first harmonic CRSF (first CRSF) at ~100 keV is only detected within a narrow phase range (0.8-1.0) accompanied by a shallow f-CRSF line. Based on these results, we speculate that when the source enters the supercritical regime, the higher accretion column height can significantly enhance the harmonic line at a narrow phase through an "anti-pencil" beam at a higher energy band. At the same time, it will also affect the behavior of the fundamental line.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2022
- DOI:
- 10.3847/1538-4357/ac6e66
- arXiv:
- arXiv:2204.11222
- Bibcode:
- 2022ApJ...932..106K
- Keywords:
-
- Binary pulsars;
- High mass x-ray binary stars;
- Accretion;
- Magnetic fields;
- 153;
- 733;
- 14;
- 994;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- doi:10.3847/1538-4357/ac6e66