Temporal Evolution of Photon Energy emitted from Two Component Advective Flows: Origin of Time Lag

Abstract

X-Ray time lag of black hole candidates contains important information regarding the emission geometry. Recently, study of time lags from observational data revealed very intriguing properties. To investigate the real cause of this lag behavior with energy and spectral states, we study photon paths inside a Two Component Advective Flow (TCAF) which appears to be a satisfactory model to explain the spectral and timing properties. We employ the Monte-Carlo simulation technique to carry out the Comptonization process. We use a relativistic thick disk in Schwarzschild geometry as the CENtrifugal pressure supported BOundary Layer (CENBOL) which is the Compton cloud. In TCAF, this is the post-shock region of the advective component. Keplerian disk on the equatorial plane which is truncated at the inner edge i.e., at the outer boundary of the CENBOL, acts as the soft photon source. Ray-tracing code is employed to track the photons to a distantly located observer. We compute the cumulative time taken by a photon during Comptonization, reflection and following the curved geometry on the way to the observer. Time lags between various hard and soft bands have been calculated. We study the variation of time lags with accretion rates, CENBOL size and inclination angle. Time lags for different energy channels are plotted for different inclination angles. The general trend of variation of time lag with QPO frequency and energy as observed in satellite data is reproduced.

In this paper, we have simulated the time lags using simplified Two Component Advective Flow (TCAF) solution. Accepted for publication in MNRAS

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Cited by in corpus (9)

• A variable corona for GRS 1915+105
• Long term X-Ray Observations of Seyfert 1 Galaxy Ark 120: On the origin of soft-excess
• Time-domain variability properties of XTE J1650-500 during its 2001 outburst: Evidence of disc-jet connection
• Evidence of Outflow Induced Soft Lags of Galactic Black Holes
• Coronal Properties of Low-Accreting AGNs using Swift, XMM-Newton and NuSTAR Observations
• Evolution of Accretion Disc Geometry of GRS~1915+105 during its $\chi$ state as revealed by TCAF solution
• Images and Spectra of Time Dependent Two Component Advective Flow in Presence of Outflows
• Detection of QPO Soft Lag during Outburst of Swift J1727.8-1613: Estimation of Instrinsic Parameters from Spectral Study
• Discovery of Jet-Induced Soft Lags of XTE J1550-564 during Its 1998 Outburst