2021/02/18 by Yuanze Ding, Y. Z. Ding, W. Wang +170
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics #Binary number #Black hole (networking) #Dissipation #Energy (signal processing) #Galaxy #Gamma-ray bursts and supernovae #Light curve #Luminosity #Neutron star #Orbital elements #Orbital period #Physics #Pulsars and Gravitational Waves Research #Stars #Wavelet #X-ray binary #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stab835
14 pages, 9 figures, and 6 tables. This work has been submitted to MNRAS after the referee's report
arxiv created 2021/02/18 · openalex publication_date 2021/03/22 · arxiv updated 2021/03/31 · openalex created_date 2021/07/05 · openalex updated_date 2026/08/06
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 3.61398 ± 0.00002 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^∘ ± 0.003^∘ \rm yr-1. The light curves are folded to sketch the pulse profiles in different energy ranges. A multi-peak structure in 1-10 keV is clearly illustrated. We introduced wavelet analysis into our data analysis procedures to study 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 ∼10 mHz. In addition, the X-ray light curves showed multiple QPOs in the period of ∼16 − 32 s 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 drifting frequently while the ∼16 − 32 s QPO scarcely drifting. The dissipation of oscillations from high energy to low energy was also observed. These features of QPOs in 4U 0115+63 provide new challenge to our understanding of their physical origins.