Low frequency X-ray timing with Gaussian processes and reverberation in the radio-loud AGN 3C 120. (arXiv:1908.06099v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Wilkins_D/0/1/0/all/0/1">D.R. Wilkins</a>
A framework is developed to perform Fourier-domain timing analysis on X-ray
light curves with gaps, employing Gaussian processes to model the probability
distribution underlying the observed time series from which continuous samples
can be drawn. A technique is developed to measure X-ray reverberation from the
inner regions of accretion discs around black holes in the low frequency
components of the variability, on timescales longer than can be probed
employing standard Fourier techniques. This enables X-ray reverberation
experiments to be performed using data from satellites in low-Earth orbit such
as NICER, NuSTAR and the proposed X-ray timing mission STROBE-X, and enables
long timescale reverberation around higher mass AGN to be measured by combining
multiple observations. Gaussian processes are applied to observations of the
broad line radio galaxy 3C120 spanning two orbits with XMM-Newton to measure
the relative time lags of successive X-ray energy bands. The lag-energy
spectrum between 5E-6 and 3E-5Hz, estimated using Gaussian processes, reveals
X-ray reverberation from the inner accretion disc for the first time in this
radio-loud AGN. Time lags in the relativistically broadened iron K line are
significantly detected. The core of the line lags behind the continuum by (3800
+/- 1500)s, suggesting a scale height of the corona of (13 +/- 8)rg above the
disc. The ability to compare the structure of coronae in radio loud AGN to
their radio quiet counterparts will yield important insight into the mechanisms
by which black holes are able to launch jets.
A framework is developed to perform Fourier-domain timing analysis on X-ray
light curves with gaps, employing Gaussian processes to model the probability
distribution underlying the observed time series from which continuous samples
can be drawn. A technique is developed to measure X-ray reverberation from the
inner regions of accretion discs around black holes in the low frequency
components of the variability, on timescales longer than can be probed
employing standard Fourier techniques. This enables X-ray reverberation
experiments to be performed using data from satellites in low-Earth orbit such
as NICER, NuSTAR and the proposed X-ray timing mission STROBE-X, and enables
long timescale reverberation around higher mass AGN to be measured by combining
multiple observations. Gaussian processes are applied to observations of the
broad line radio galaxy 3C120 spanning two orbits with XMM-Newton to measure
the relative time lags of successive X-ray energy bands. The lag-energy
spectrum between 5E-6 and 3E-5Hz, estimated using Gaussian processes, reveals
X-ray reverberation from the inner accretion disc for the first time in this
radio-loud AGN. Time lags in the relativistically broadened iron K line are
significantly detected. The core of the line lags behind the continuum by (3800
+/- 1500)s, suggesting a scale height of the corona of (13 +/- 8)rg above the
disc. The ability to compare the structure of coronae in radio loud AGN to
their radio quiet counterparts will yield important insight into the mechanisms
by which black holes are able to launch jets.
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