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Title: CALCULATING TIME LAGS FROM UNEVENLY SAMPLED LIGHT CURVES

Timing techniques are powerful tools to study dynamical astrophysical phenomena. In the X-ray band, they offer the potential of probing accretion physics down to the event horizon. Recent work has used frequency- and energy-dependent time lags as tools for studying relativistic reverberation around the black holes in several Seyfert galaxies. This was achieved due to the evenly sampled light curves obtained using XMM-Newton. Continuously sampled data are, however, not always available and standard Fourier techniques are not applicable. Here, building on the work of Miller et al., we discuss and use a maximum likelihood method to obtain frequency-dependent lags that takes into account light curve gaps. Instead of calculating the lag directly, the method estimates the most likely lag values at a particular frequency given two observed light curves. We use Monte Carlo simulations to assess the method's applicability and use it to obtain lag-energy spectra from Suzaku data for two objects, NGC 4151 and MCG-5-23-16, that had previously shown signatures of iron K reverberation. The lags obtained are consistent with those calculated using standard methods using XMM-Newton data.
Authors:
;  [1] ;  [2]
  1. Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)
  2. Department of Physics and Astronomy, Wayne State University, 666 W. Hancock Street, Detroit, MI 48201 (United States)
Publication Date:
OSTI Identifier:
22270684
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 777; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; BLACK HOLES; COMPUTERIZED SIMULATION; DATA ANALYSIS; ENERGY DEPENDENCE; ENERGY SPECTRA; FREQUENCY DEPENDENCE; GALAXY NUCLEI; IRON; MAXIMUM-LIKELIHOOD FIT; MONTE CARLO METHOD; POTENTIALS; RELATIVISTIC RANGE; SEYFERT GALAXIES; VISIBLE RADIATION; X RADIATION