Time-domain variability properties of XTE J1650-500 during its 2001 outburst: Evidence of disc-jet connection

TL;DR

This study analyzes the variability properties of XTE J1650-500 during its 2001 outburst, revealing delays, QPO behavior, and energy-dependent lags, which suggest a disk-jet connection near the black hole.

Contribution

It provides a detailed analysis of the evolution of timing properties and their energy dependence during the outburst, highlighting unique variability features of XTE J1650-500.

Findings

12-day delay between hard and soft X-ray light-curves

High rms QPOs observed in lower energy range

Anti-correlation and later correlation between QPO frequency and time lag

Abstract

Evolution of variability properties of Galactic transient sources is a diagnostic tool to understand various regimes of the accretion flow and its dynamics close to the central black hole. In this paper, we concentrate on the variability properties of the X-ray transient XTE J1650-500 and investigate the evolution of viscous delay, time lag, QPO frequency, and their energy dependence throughout the rising phase as observed by RXTE during its outburst in 2001. Our analysis reveals (1) a delay of 12 \pm 1 days between one day averaged hard (5-12 keV) and soft (1.5-3 keV) photon light-curves as observed by RXTE/ASM; (2) QPOs with high rms values are observed in lower energy (4-8 keV) range; (3) the QPO frequencies and associated time lags were anti-correlated during the initial days of the rising phase, and later on, they were found to be correlated; (4) the time lags of iron line photons with respect to hard and soft photons remained almost constant during the initial days of hard state and the lag magnitude increased during the state transition. We perform comparative studies with outbursts of GX 339-4 and XTE J1550-564. We find the evolution of time lags associated with the QPO characteristics during the outburst - stronger QPOs at low energy, and constant lags of broad Fe-line photons present a unique nature of outburst profile in XTE J1650-500. The possible cause of such variabilities is explained by considering disk-jet geometry closer to the central black hole.