Modeling fast X-ray variability around an accreting black hole

Abstract

X-ray inter-band time lags are observed during the outbursts of black hole X-ray binaries (BHXRBs). Timing analysis of fast variability in low Fourier frequency bands shows that high-energy photons lag behind low-energy photons, a phenomenon referred to as hard lag. Conversely, in high Fourier frequency bands, low-energy photons lag behind high-energy photons, known as soft lag. This frequency-dependent lag spectrum suggests that the lags arise from different physical processes. Notably, a trend has been observed wherein the lags shift towards shorter timescales during the rising hard state, indicating an evolution in the inner accretion flow. In this study, we simulate these inter-band lags by conducting Monte Carlo simulations of the rapid variability within the geometry of a jet base corona. We consider both inward propagating accretion rate fluctuations and reverberation (light crossing) delays in our simulations. We successfully reproduce both low-frequency hard lags and high-frequency soft lags in a self-consistent manner. We replicate the observed evolution of the frequency-dependent lag spectra by varying the geometrical scale of the corona and the viscous frequency of the disc. Finally, we discuss the potential of a spherical corona and emphasize that polarization observations from the Imaging X-ray Polarimetry Explorer (IXPE) and the enhanced X-ray Timing and Polarimetry mission (eXTP) will be crucial for distinguishing the corona's geometry in future studies.

17 pages, 9 figures, accepted by ApJ

References in corpus (65)

• X-ray Properties of Black-Hole Binaries
• Advection-Dominated Accretion and the Spectral States of Black Hole X-Ray Binaries: Application to Nova Muscae 1991
• Modelling the behaviour of accretion flows in X-ray binaries
• Millisecond Oscillations in X-Ray Binaries
• X-ray reflected spectra from accretion disk models. III. A complete grid of ionized reflection calculations
• X-ray reverberation around accreting black holes
• Low frequency QPO spectra and Lense-Thirring precession
• Investigating a Fluctuating-accretion Model for the Spectral-timing Properties of Accreting Black Hole Systems
• On the X-ray time lags in the black hole candidates
• Irradiation of an Accretion Disc by a Jet: General Properties and Implications for Spin Measurements of Black Holes
• A review of quasi-periodic oscillations from black hole X-ray binaries: observation and theory
• The disc instability model for X-ray transients: evidence for truncation and irradiation
• The flux-dependent amplitude of broadband noise variability in X-ray binaries and active galaxies
• States and transitions in black-hole binaries
• Radiative Processes, Spectral States and Variability of Black-Hole Binaries
• The corona contracts in a black-hole transient
• Stingray: A Modern Python Library For Spectral Timing
• A physical model for the continuum variability and QPO in accreting black holes
• Normalizing a Relativistic Model of X-ray Reflection: The Definition of the Reflection Fraction and its Implementation in relxill
• Polarized x-rays constrain the disk-jet geometry in the black hole x-ray binary Cygnus X-1
• X-ray spectra of accretion discs with dynamic coronae
• An exact analytic treatment of propagating mass accretion rate fluctuations in X-ray binaries
• Modelling variability in black hole binaries: linking simulations to observations
• General relativistic modelling of the negative reverberation X-ray time delays in AGN
• Discovery of oscillations above 200 keV in a black hole X-ray binary with Insight-HXMT
• A public relativistic transfer function model for X-ray reverberation mapping of accreting black holes
• MAXI J1820+070 with NuSTAR I. An increase in variability frequency but a stable reflection spectrum: coronal properties and implications for the inner disc in black hole binaries
• The origin of the lag spectra observed in AGN: Reverberation and the propagation of X-ray source fluctuations
• Towards modelling X-ray reverberation in AGN: Piecing together the extended corona
• A dynamic black hole corona in an active galaxy through X-ray reverberation mapping
• Insight-HXMT observations of the New Black Hole Candidate MAXI J1535-571: timing analysis
• Disk, Corona, Jet Connection in the Intermediate State of MAXI J1820+070 Revealed by NICER Spectral-Timing Analysis
• Coupling between the accreting corona and the relativistic jet in the micro quasar GRS 1915+105
• Evidence of a Broad Relativistic Iron Line from the Neutron Star Low-Mass X-ray Binary Serpens X-1
• Insight-HXMT observations of jet-like corona in a black hole X-ray binary MAXI J1820+070
• Constraining the size of the corona with fully relativistic calculations of spectra of extended corona. I - the Monte Carlo radiative transfer code
• A jet model for Galactic black-hole X-ray sources: Some constraining correlations
• Spectral-timing evidence for a Very High State in the Narrow Line Seyfert 1 Ark 564
• Evolution of the reverberation lag in GX 339-4 at the end of an outburst
• The NICER "Reverberation Machine": A Systematic Study of Time Lags in Black Hole X-Ray Binaries
• The Effect of Returning Radiation on Relativistic Reflection
• The evolution of the corona in MAXI J1535-571 through type-C quasi-periodic oscillations with Insight-HXMT
• X-ray quasi-periodic oscillations in Lense--Thirring precession model - I. variability of relativistic continuum
• NICER, NuSTAR and Insight-HXMT views to the newly discovered black hole X-ray binary Swift J1727.8--1613
• Observations of a black hole X-ray binary indicate formation of a magnetically arrested disk
• The Evolution of the Phase Lags Associated with the Type-C Quasi-periodic Oscillation in GX 339--4 during the 2006/2007 Outburst
• An X-ray reverberation mass measurement of Cygnus X-1
• Simultaneous spectral and reverberation modelling of relativistic reflection in Mrk 335
• Multi-Wavelength Variability. Accretion and Ejection at the Fastest Timescales
• MAXI J1820+070 X-ray spectral-timing reveals the nature of the accretion flow in black hole binaries
• Accretion flow diagnostics with X-ray spectral-timing: the hard state of SWIFT J1753.5-0127
• Testing wind as an explanation for the spin problem in the continuum-fitting method
• X-ray short-time lags in the Fe-K energy band produced by scattering clouds in active galactic nuclei
• X-ray quasi-periodic oscillations in Lense-Thirring precession model -- II. variability of relativistic iron K$\alpha$ line
• Spectral and polarization properties of reflected X-ray emission from black hole accretion discs
• AstroSat view of the newly discovered X-ray transient MAXI~J1803--298 in the Hard-intermediate state
• Bulk Motions in the Black Hole Jet Sheath as a Candidate for the Comptonizing Corona
• Black holes: Timing and spectral properties and evolution
• Low Frequency Quasi-periodic Oscillation in MAXI J1820+070: Revealing distinct Compton and Reflection Contributions
• Optical polarization signatures of black hole X-ray binaries
• Observations of X-ray reverberation around black holes
• Probing black-hole accretion through time variability
• Evidence for a dynamic corona in the short-term time lags of black hole X-ray binary MAXI J1820+070
• Multi-wavelength observation of MAXI J1348$-$630 during the outburst in 2019
• Impact of the returning radiation on X-ray reflection spectroscopy measurements: the case of Galactic black holes