Detection of low-frequency breaks in power density spectrum of GX 339-4 in faint low/hard state observations using AstroSat data

Abstract

We present the spectro-timing analysis of the black hole binary system GX 339-4 using AstroSat data extracted at the beginning of outbursts in 2017 and 2019. The joint spectral fitting of LAXPC and SXT data revealed that the source was in a faint low/hard state for both 2017 and 2019 observations with a nearly equal photon index of $\sim$1.57 and $\sim$1.58 and with Eddington ratio, $L/L_{Edd}$, of 0.0011 and 0.0046 respectively. The addition of a reflection component into the spectral modelling improved the fit ($\Delta {\chi }^2$ $\approx 6$ for 2017 and $\Delta {\chi }^2$ $\approx 7$ for 2019), pointing towards the presence of weak reflection features arising due to irradiation of the accretion disk. The power density spectrum (PDS) consisted of strong band-limited noise with a break at low frequencies, described with a combination of few zero-centered Lorentzian. The fitting revealed a low-frequency break at $\sim$6~mHz for 2017 and at $\sim$11~mHz for 2019 observation, whose detection is validated by results from independent detectors (LAXPCs and SXT). The break frequency is roughly consistent with results obtained from earlier observations that showed an evolution of the frequency with flux, which is in accordance with the truncated disk model. Associating the break frequency with viscous time scale of the accretion disk, we estimated a truncation radius of $\sim$93 and $\sim$61 gravitational radius for 2017 and 2019 observation, respectively.

arXiv commentAccepted for publication in MNRAS

References in corpus (32)

• Modelling the behaviour of accretion flows in X-ray binaries
• A Unified Description of the Timing Features of Accreting X-ray Binaries
• RXTE Observation of Cygnus X-1: II. Timing Analysis
• The evolution of black hole states
• Radio / X-ray correlation in the low/hard state of GX 339--4
• The ABC of low-frequency quasi-periodic oscillations in Black-Hole Candidates: analogies with Z-sources
• Broad emission lines for negatively spinning black holes
• Soft state of Cygnus X-1: stable disk and unstable corona
• A Global Spectral Study of Black Hole X-ray Binaries
• The broad-band power spectra of X-ray binaries
• Are There Three Peaks in the Power Spectra of GX 339-4 and Cyg X-1?
• A physical model for the continuum variability and QPO in accreting black holes
• X-ray Reflection Spectroscopy of the Black Hole GX 339-4: Exploring the Hard State with Unprecedented Sensitivity
• Accretion flow dynamics during the evolution of timing and spectral properties of GX 339-4 during its 2010-11 outburst
• The Distance and Interstellar Sight Line to GX339-4
• Truncation of the Inner Accretion Disk around a Black Hole at Low Luminosity
• Low Luminosity States of the Black Hole Candidate GX~339--4. II. Timing Analysis
• The mass function of GX 339-4 from spectroscopic observations of its donor star
• Large Area X-ray Proportional Counter (LAXPC) Instrument on AstroSat and Some Preliminary Results from its performance in the orbit
• The truncated and evolving inner accretion disc of the black hole GX 339-4
• The evolution of GX 339-4 in the low-hard state as seen by NuSTAR and Swift
• Power spectra of black holes and neutron stars as a probe of hydrodynamical structure of the source. Diffusion theory and its application to Cyg X-1 and Cyg X-2 X-ray observations
• Two-phase radiative/conductive equilibrium in AGN and GBH
• ``Canonical'' Black Hole States in the Superluminal Source GRO J1655-40
• The X-ray binary GX 339-4/V821 Ara: the distance, inclination, evolutionary status and mass transfer
• Time-dependent models of two-phase accretion discs around black holes
• The 2017 Failed Outburst of GX 339-4: Relativistic X-ray Reflection near the Black Hole Revealed by NuSTAR and Swift Spectroscopy
• The return to the hard state of GX 339-4 as seen by Suzaku
• Measurement of Hard Lags and Coherences in the X-Ray Flux of Accreting Neutron Stars and Comparison with Accreting Black Holes
• Correlation between radio luminosity and X-ray timing frequencies in neutron star and black hole X-ray binaries
• Black-Hole Transients : From QPOs to Relativistic Jets
• NuSTAR and XMM-Newton observations of the 2015 outburst decay of GX 339-4

Cited by in corpus (4)

• Reflare in MAXI J1348-630]{Evolution of disc and corona in MAXI J1348-630 during the 2019 reflare: NICER and Insight-HXMT view
• Broadband spectro-temporal investigation of neutron star low-mass X-ray binary GX 349+2
• Probing the soft state evolution of 4U 1543-47 during its 2021 outburst using AstroSat
• Properties of 2017-18 'failed' Outburst of GX 339-4