160 citations · 433 across the 13 of their papers we have counts for
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SAX J1808.4-3658 and the origin of X-ray variability in X-ray binaries and active galactic nuclei
Philip Uttley
The aperiodic X-ray variability in neutron star and black hole X-ray binaries (XRBs), and active galactic nuclei (AGN) shows a characteristic linear relationship between rms amplit…
Combined Long and Short Timescale X-ray Variability of NGC4051 with RXTE and XMM-Newton
I. M. McHardy, I. E. Papadakis, P. Uttley +2
We present over 6.5 years of frequent X-ray observations of the NLS1 galaxy NGC4051 by RXTE together with a >100ks observation by XMM-Newton and so derive a 2-10 keV PSD covering a…
Complex X-ray spectral behaviour of NGC 4051 in the low flux state
P. Uttley, R. D. Taylor, I. M. McHardy +4
The Narrow Line Seyfert 1 galaxy NGC 4051 was observed in one of its prolonged low-lux states by XMM-Newton in November 2002. Here we present the results of an analysis of EPIC-pn…
Catching NGC4051 in the low state with XMM-Newton
P. Uttley, R. D. Taylor, I. M. McHardy +4
The Narrow Line Seyfert 1 galaxy NGC4051 shows unusual low flux states, lasting several months, when the 2-10 keV X-ray spectrum becomes unusually hard (photon index<1) while the s…
Constraints on AGN accretion disc viscosity derived from continuum variability
Rhaana L. C. Starling, Aneta Siemiginowska, Phil Uttley +1
We estimate a value of the viscosity parameter in AGN accretion discs for the PG quasar sample. We assume that optical variability on time-scales of months to years is caused by lo…
Combined Long and Short Timescale X-ray Variability of NGC4051 with RXTE and XMM-Newton
I. M. McHardy, I. E. Papadakis, P. Uttley +2
We present a comprehensive examination of the X-ray variability of the narrow line Seyfert 1 (NLS1) galaxy NGC4051. We combine over 6.5 years of frequent monitoring observations by…