Hard X-ray Lags in Cygnus X-1

Abstract

We have used the Fourier cross spectra of Cyg X-1, as obtained with BATSE during a period of almost 2000 days, to estimate the phase (or time) lags between X-ray flux variations in the 20-50 keV and the 50-100 keV bands as a function of Fourier frequency, nu. We find that these lag spectra do not depend on source state, as measured by the fractional rms variations of the X-ray flux. For frequencies well below the Nyquist frequency the variations in the 50-100 keV band lag those in the 20-50 keV band by a time interval proportional to nu^{-0.8}. Binning effects cause the observed hard X-ray time lags to decrease to zero at the Nyquist frequency. Some previous results on time lags were affected by these binning effects. At photon energies above 10 keV the time lags are approximately proportional to the logarithm of the ratio the energies of the passbands used.

arXiv commentTo appear in Astrophysical Journal Letters

References in corpus (4)

• The 1996 Soft State Transitions of Cygnus X-1
• Phase Lags and Coherence of X-Ray Variability in Black Hole Candidates
• Correlation Between BATSE Hard X-ray Spectral and Timing Properties of Cygnus X-1
• Five Years in the Life of Cygnus X-1: BATSE Long-Term Monitoring

Cited by in corpus (24)

• RXTE Observation of Cygnus X-1: II. Timing Analysis
• Spectral-timing evidence for a Very High State in the Narrow Line Seyfert 1 Ark 564
• RXTE Observation of Cygnus X--1: III. Implications for Compton Corona and ADAF Models
• A New Model for the Hard Time Lags in Black Hole X-Ray Binaries
• Phase Lag and Coherence Function of X-ray emission from Black Hole Candidate XTE J1550-564
• Comparison of time/phase lags in the hard state and plateau state of GRS 1915+105
• Measurement of Hard Lags and Coherences in the X-Ray Flux of Accreting Neutron Stars and Comparison with Accreting Black Holes
• Modeling The X-ray Timing Properties Of Cygnus X-1 As Caused By Waves Propagating In A Transition Disk
• The photon-index - time-lag correlation in black-hole X-ray binaries
• Statistical properties of Fourier-based time-lag estimates
• Probing the Structure of Accreting Compact Sources Through X-Ray Time Lags and Spectra
• Accretion flow diagnostics with X-ray spectral-timing: the hard state of SWIFT J1753.5-0127
• Timing in the Time Domain: Cygnus X-1
• Energy Dependent time lags in the Seyfert 1 galaxy NGC 4593
• Hard X-ray variability of the black-hole candidate GRO J0422+32 during its 1992 outburst
• Timing Noise Properties of GRO J0422+32
• Coronal cooling and its signatures in the rapid aperiodic variability of Galactic black-hole candidates
• A theoretical study of the time-lags due to Comptonization and the constraints on the X-ray corona in AGN
• Hard X-ray lags in GRO J1719-24
• The cross-correlation analysis in Z source GX 349+2
• The role of outflows in black-hole X-ray binaries
• Timing Analysis of V404 Cyg during Its Brightest Outburst with INTEGRAL/SPI
• XMM-Newton detection of soft time lags in the TDE candidate AT 2018fyk
• An Analytical Fourier-Transformation Model for the Production of Hard and Soft X-Ray Time Lags in AGNs: Application to 1H 0707-495