CALCULATING TIME LAGS FROM UNEVENLY SAMPLED LIGHT CURVES

Journal Article · Fri Nov 01 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/777/1/24· OSTI ID:22270684

Zoghbi, A.; Reynolds, C. ^[1]

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1. Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)

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.

• OSTI ID: 22270684
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 777; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
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