Spectro-temporal study of atoll source GX 9+9 observed with AstroSat

TL;DR

This study analyzes the spectral and temporal properties of the low-mass X-ray binary GX 9+9 using AstroSat data, revealing a soft state with disk-dominated emission and broad noise components across flux levels.

Contribution

First detailed spectro-temporal analysis of GX 9+9 with AstroSat, estimating key source parameters and characterizing variability in the soft state.

Findings

Source in soft state with disk-dominated spectrum

Presence of broad Lorentzian noise components

Estimated inner-disk radius and temperature

Abstract

In this work, we performed a spectro-temporal investigation of the low-mass X-ray binary GX 9+9 using the Large Area X-ray Proportional Counter (LAXPC) and Soft X- ray Telescope (SXT) observation on board AstroSat. The source was detected in the soft state during the observation, which results in a disk dominating energy spectrum within the energy range of 0.7-25.0 keV. We carried out the analysis at different flux levels. In the temporal analysis, LAXPC data in all flux levels showed the presence of noise components, describing broad Lorentzian components. We modeled the energy-dependent temporal properties of the source in order to identify the radiative origin of the observed variability. This source is not a well-studied source; hence we attempt to estimate various source characteristics like inner-disk radius, flux, and inner-disk temperature.