QPOs and orbital elements of X-ray binary 4U 0115+63 during the 2017 outburst observed by Insight-HXMT. Issue 4 (24th March 2021)

• Record Type: Journal Article
• Authors: Ding, Y Z; Wang, W; Zhang, P; Bu, Q C; Cai, C; Cao, X L; Zhi, C; Chen, L; Chen, T X; Chen, Y B; Chen, Y; Chen, Y P; Cui, W W; Du, Y Y; Gao, G H; Gao, H; Ge, M Y; Gu, Y D; Guan, J; Guo, C C; Han, D W; Huang, Y; Huo, J; Jia, S M; Jiang, W C; Jin, J; Kong, L D; Li, B; Li, C K; Li, G; Li, T P; Li, W; Li, X; Li, X B; Li, X F; Li, Z W; Liang, X H; Liao, J Y; Liu, B S; Liu, C Z; Liu, H X; Liu, H W; Liu, X J; Lu, F J; Lu, X F; Lou, Q; Luo, T; Ma, R C; Ma, X; Meng, B; Nang, Y; Nie, J Y; Qu, J L; Ren, X Q; Sai, N; Song, L M; Song, X Y; Sun, L; Tan, Y; Tao, L; Tuo, Y L; Wang, C; Wang, L J; Wang, P J; Wang, W S; Wang, Y S; Wen, X Y; Wu, B Y; Wu, B B; Wu, M; Xiao, G C; Xiao, S; Xiong, S L; Xu, Y P; Yang, R J; Yang, S; Yang, Y J; Yi, Q B; Yin, Q Q; You, Y; Zhang, F; Zhang, H M; Zhang, J; Zhang, P; Zhang, S; Zhang, S N; Zhang, W C; Zhang, W; Zhang, Y F; Zhang, Y H; Zhao, H S; Zhao, X F; Zheng, S J; Zheng, Y G; Zhou, D K;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 503:Issue 4(2021)
• Page Start: 6045
• Page End: 6058
• Publication Date: 2021-03-24
• Subjects: stars: individual: 4U 0115+63 -- X-rays: binaries -- X-rays: stars; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab835
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: In this paper, we presented a detailed timing analysis of a prominent outburst of 4U 0115+63 detected by Insight -HXMT in 2017 August. The spin period of the neutron star was determined to be 3.613 98 ± 0.000 02 s at MJD 57978. We measured the period variability and extract the orbital elements of the binary system. The angle of periastron evolved with a rate of $0.048^\circ \pm 0.003^\circ \rm \, yr^{-1}$ . The light curves are folded to sketch the pulse profiles in different energy ranges. A multipeak structure in 1–10 keV is clearly illustrated. We introduced wavelet analysis into our data analysis procedures to study quasi-periodic oscillation (QPO) signals and perform a detailed wavelet analysis in many different energy ranges. Through the wavelet spectra, we report the discovery of a QPO at the frequency of ∼10 mHz. In addition, the X-ray light curves showed multiple QPOs in the period of ∼16–32 and ∼67–200 s. We found that the ∼100 s QPO was significant in most of the observations and energies. There exist positive relations between X-ray luminosity and their Q-factors and S-factors, while the QPO periods have no correlation with X-ray luminosity. In wavelet phase maps, we found that the pulse phase of ∼67–200 s QPO is drifting frequently while that of ∼16–32 s QPO is scarcely drifting. The dissipation of oscillations from high energy to low energy was also observed. These features of QPOs in 4U 0115+63 provide a new challenge to our understanding of their physical origins.