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arXiv · 2308.06978

NuSTAR and AstroSat observations of GX 9$+$1: Spectral and temporal studies

Neal Titus Thomas·S. B. Gudennavar·S. G. Bubbly
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Abstract

We have studied the spectro-temporal properties of the neutron star low mass X-ray binary GX 9$+$1 using data from \textit{NuSTAR/FPM} and \textit{AstroSat/SXT} and \textit{LAXPC}. The hardness-intensity diagram of the source showed it to be in the soft spectral state during both observations. \textit{NuSTAR} spectral analysis yielded an inclination angle ($\theta$) $=$ 29$\substack{+3\\-4}^{\circ}$ and inner disk radius ($R_{in}$) $\leq$ 19.01 km. Assuming that the accretion disk was truncated at the Alfv\'en radius during the observation, the upper limit of the magnetic dipole moment ($\mu$) and the magnetic field strength ($B$) at the poles of the neutron star in GX 9$+$1 were calculated to be 1.45$\times$$10^{26}$ G cm$^3$ and 2.08$\times$$10^8$ G, respectively (for $k_A$ $=$ 1). Flux resolved spectral analysis with \textit{AstroSat} data showed the source to be in the soft spectral state ($F_{disk}$/$F_{total}$ $\sim$0.9) with a monotonic increase in mass accretion rate ($\dot{m}$) along the banana branch. The analysis also showed the presence of absorption edges at $\sim$1.9 and $\sim$2.4 keV, likely due to Si XIII and S XV, respectively. Temporal analysis with \textit{LAXPC-20} data in the 0.02 $-$ 100 Hz range revealed the presence of noise components, which could be characterized with broad Lorentzian components.

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Neal Titus Thomas, S. B. Gudennavar, S. G. Bubbly. 2023-08-14. NuSTAR and AstroSat observations of GX 9$+$1: Spectral and temporal studies. https://doi.org/10.1093/mnras/stad2379

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