Unveiling the Temporal Properties of MAXI J1820+070 through AstroSat Observations
Sneha Prakash Mudambi, Bari Maqbool, Ranjeev Misra, Sabhya Hebbar, J. S. Yadav, Shivappa B. Gudennavar, Bubbly S. G.
Abstract
Abstract We present here the results of the first broadband simultaneous spectral and temporal studies of the newly detected black hole binary MAXI J1820+070 as seen by Soft X-ray Telescope and Large Area X-ray Proportional Counter (LAXPC) on board AstroSat . The observed combined spectra in the energy range 0.7–80 keV were well modeled using disk blackbody emission, thermal Comptonization, and a reflection component. The spectral analysis revealed that the source was in its hard spectral state (Γ = 1.61) with a cool disk ( kT in = 0.22 keV). We report the energy dependent time-lag and root mean squared (rms) variability at different frequencies in the energy range 3–80 keV using LAXPC data. We also modeled the flux variability using a single-zone stochastic propagation model to quantify the observed energy dependence of time lag and fractional rms variability, and then compared the results with that of Cygnus X-1. Additionally, we confirm the detection of a quasi-periodic oscillation with the centroid frequency at 47.7 mHz.