Switches between accretion structures during flares in 4U 1901+03
Author:
Ji L1ORCID, Ducci L12, Santangelo A13, Zhang S3, Suleimanov V145, Tsygankov S56ORCID, Doroshenko V15ORCID, Nabizadeh A6ORCID, Zhang S N37, Ge M Y3, Tao L3, Bu Q C13, Qu J L3, Lu F J3, Chen L8, Song L M37, Li T P379, Xu Y P37, Cao X L3, Chen Y3, Liu C Z3, Cai C37, Chang Z3, Chen G3, Chen T X3, Chen Y B10, Chen Y P3, Cui W9, Cui W W3, Deng J K10, Dong Y W3, Du Y Y3, Fu M X10, Gao G H37, Gao H37, Gao M3, Gu Y D3, Guan J3, Guo C C37, Han D W3, Huang Y37, Huo J3, Jia S M3, Jiang L H3, Jiang W C3, Jin J3, Jin Y J11, Kong L D37, Li B3, Li C K3, Li G3, Li M S3, Li W3, Li X3, Li X B3, Li X F3, Li Y G3, Li Z W3, Liang X H3, Liao J Y3, Liu B S3, Liu G Q10, Liu H X37, Liu H W3, Liu X J3, Liu Y N11, Lu B3, Lu X F3, Luo Q37, Luo T3, Ma X3, Meng B3, Nang Y37, Nie J Y3, Ou G3, Sai N37, Shang R C10, Song X Y3, Sun L3, Tan Y3, Tuo Y L37, Wang C712, Wang G F3, Wang J3, Wang P J37, Wang W S3, Wang Y S3, Wen X Y3, Wu B Y37, Wu B B3, Wu M3, Xiao G C37, Xiao S37, Xiong S L3, Xu H3, Yang J W3, Yang S3, Yang Yan-Ji3, Yang Yi-Jung3, Yi Q B313, Yin Q Q3, You Y37, Zhang A M3, Zhang C M3, Zhang F3, Zhang H M3, Zhang J3, Zhang P3, Zhang T3, Zhang W37, Zhang W C3, Zhang W Z8, Zhang Yi3, Zhang Y F3, Zhang Y J3, Zhang Y H37, Zhang Yue37, Zhang Zhao10, Zhang Zhi11, Zhang Z L3, Zhao H S3, Zhao X F37, Zheng S J3, Zhou D K37, Zhou J F11, Zhu Y X314, Zhu Y3, Zhuang R L11
Affiliation:
1. Institut für Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Eberhard Karls Universität, Sand 1, D-72076 Tübingen, Germany 2. ISDC Data Center for Astrophysics, Université de Genève, Chemin d’Écogia 16, CH-1290 Versoix, Switzerland 3. Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Beijing 100049, China 4. Kazan (Volga region) Federal University, Kremlevskaya str 18, Kazan 42008, Russia 5. Space Research Institute of the Russian Academy of Sciences, Profsoyuznaya str 84/32, Moscow 117997, Russia 6. Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland 7. University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049, China 8. Department of Astronomy, Beijing Normal University, Beijing 100088, China 9. Department of Astronomy, Tsinghua University, Beijing 100084, China 10. Department of Physics, Tsinghua University, Beijing 100084, China 11. Department of Engineering Physics, Tsinghua University, Beijing 100084, China 12. Key Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China 13. School of Physics and Optoelectronics, Xiangtan University, Yuhu District, Xiangtan, Hunan 411105, China 14. College of Physics, Jilin University, No.2699 Qianjin Street, Changchun City 130012, China
Abstract
ABSTRACT
We report on our analysis of the 2019 outburst of the X-ray accreting pulsar 4U 1901+03 observed with Insight-HXMT and NICER. Both spectra and pulse profiles evolve significantly in the decaying phase of the outburst. Dozens of flares are observed throughout the outburst. They are more frequent and brighter at the outburst peak. We find that the flares, which have a duration from tens to hundreds of seconds, are generally brighter than the persistent emission by a factor of ∼1.5. The pulse-profile shape during the flares can be significantly different from that of the persistent emission. In particular, a phase shift is clearly observed in many cases. We interpret these findings as direct evidence of changes of the pulsed beam pattern, due to transitions between the sub- and supercritical accretion regimes on a short time-scale. We also observe that at comparable luminosities the flares’ pulse profiles are rather similar to those of the persistent emission. This indicates that the accretion on the polar cap of the neutron star is mainly determined by the luminosity, i.e. the mass accretion rate.
Funder
Cancer Nurses Society of Australia Center for Advanced Study, University of Illinois at Urbana-Champaign Key Research and Development Project Ministry of Science and Technology National Natural Science Foundation of China Russian Science Foundation Deutsche Forschungsgemeinschaft
Publisher
Oxford University Press (OUP)
Subject
Space and Planetary Science,Astronomy and Astrophysics
Cited by
16 articles.
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