Comprehensive investigations on spectral and temporal features of GX 5-1 using AstroSat observations
subject: accretion, accretion discs; stars: neutron; X-rays: binaries; X-rays: individual: GX 5-1
description: Comprehensive spectrotemporal analyses of the Z-type neutron star low-mass X-ray binary GX 5-1 were performed using 10 broad-band observations from AstroSat/Soft X-ray Telescope and Large Area X-ray Proportional Counter (LAXPC) instruments. The LAXPC-20 hardness-intensity diagram showed horizontal and normal branches (HBs and NBs) of the Z track which exhibited secular motion. The time-averaged spectra in the energy range 0.7-25.0 keV could be fitted with the model combination -Cconstant tbabs edge edge thcomp diskbb. This yielded ? ?2, kTe ?3.3 keV, and Fdisc/Ftotal ? 0.8 indicating the soft/intermediate spectral state of the source during the observations. Flux-resolved spectral analysis revealed a positive correlation between kTin and Fbol. However, a negative correlation was observed between them in one of the NBs. Time-averaged temporal analysis revealed multiple HB oscillations (HBOs) and NB oscillations (NBOs), and peaked noise components in the ?5-50 Hz range. Furthermore, flux-resolved temporal analysis showed that the frequency of the HBOs correlates positively whereas the strength of HBOs correlates negatively with Fbol, indicating their probable origin from the accretion disc. In contrast, the frequency and strength of NBOs remain fairly constant with Fbol, suggesting that they originate from a different region in the system. Using the relativistic precession model along with highest frequency of the HBO, the upper limits of the magnetic dipole moment (?) and field strength (B) at the poles of the neutron star in the system were found to be 25.60 1025G cm3 and 3.6408 G, respectively, for kA= 1. 2024 The Author(s).
creator: Thomas N.T.; Giridharan L.; Gudennavar S.B.; Bubbly S.G.
source: Monthly Notices of the Royal Astronomical Society, Vol-534, No. 4, pp. 3068-3086.
publisher: Oxford University Press
date: 2024-01-01
rights: All Open Access; Gold Open Access
relation: ISSN: 358711; CODEN: MNRAA
format: Online
language: English
type: Article
coverage: Thomas N.T., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India; Giridharan L., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India; Gudennavar S.B., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India; Bubbly S.G., Department of Physics and Electronics, CHRIST University, Karnataka, Bangalore, 560029, India