Kong, Ling-DaLing-DaKongZhang, ShuShuZhangJi, LongLongJiDoroshenko, VictorVictorDoroshenkoSantangelo, AndreaAndreaSantangeloORLANDINI, MAUROMAUROORLANDINIFrontera, FilippoFilippoFronteraLi, JianJianLiChen, Yu-PengYu-PengChenWang, Peng-JuPeng-JuWangChang, ZhiZhiChangQu, Jin-LuJin-LuQuZhang, Shuang-NanShuang-NanZhang2022-07-132022-07-1320220004-637Xhttp://hdl.handle.net/20.500.12386/32467We 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.STAMPAenArticle10.3847/1538-4357/ac6e66000813912400001https://iopscience.iop.org/article/10.3847/1538-4357/ac6e66https://arxiv.org/pdf/2204.112222022ApJ...932..106KFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation::PE9_10 High energy and particle astronomy – X-rays, cosmic rays, gamma rays, neutrinos