418 citations · 491 across the 7 of their papers we have counts for
7 papers
The variability of active galaxies: I. Broad-band noise X-ray power spectra from XMM-Newton and Swift
Mehdy Lefkir, Simon Vaughan, Mike Goad +2
Accreting supermassive black holes at the centres of galaxies are the engine of active galactic nuclei (AGN). X-ray light curves of unabsorbed AGN show dramatic random variability…
Long term variability of Cygnus X-1. IX. A spectral-timing comparison of Cygnus X-1 and MAXI J1820+070 in the hard state
Arkadip Basak, Phil Uttley, Niek Bollemeijer +11
Cygnus X-1 is a persistent, high-mass black hole X-ray binary (BHXRB) which in the hard state shows many similar properties to transient BHXRBs, along with intriguing differences,…
Modelling variability power spectra of active galaxies from irregular time series
Mehdy Lefkir, Simon Vaughan, Daniela Huppenkothen +2
A common feature of Active Galactic Nuclei (AGN) is their random variations in brightness across the whole emission spectrum, from radio to -rays. Studying the nature and origin…
Intensive broadband reverberation mapping of Fairall 9 with 1.8 years of daily Swift monitoring
R. Edelson, B. M. Peterson, J. Gelbord +5
We present 1.8 years of near-daily Swift monitoring of the bright, strongly variable Type 1 AGN Fairall 9. Totaling 575 successful visits, this is the largest such campaign reporte…
Investigating the Hard State of MAXI J1820+070: A Comprehensive Bayesian Approach to Black Hole Spin and Accretion Properties
Sachin D. Dias, Simon Vaughan, Mehdy Lefkir +1
We analyse the X-ray spectrum of the black hole X-ray binary MAXI J1820+070 using observations from XMM-Newton and NuSTAR during 'hard' states of its 2018-2019 outburst. We take a…
Kepler observations of rapid optical variability in the BL Lac object W2R1926+42
R. Edelson, R. Mushotzky, S. Vaughan +4
We present the first Kepler monitoring of a strongly variable BL Lac, W2R1926+42. The light curve covers 181 days with ~0.2% errors, 30 minute sampling and >90% duty cycle, showing…
The early X-ray emission from GRBs
P. T. O'Brien, R. Willingale, J. Osborne +29
We present observations of the early X-ray emission for a sample of 40 gamma-ray bursts (GRBs) obtained using the Swift satellite for which the narrow-field instruments were pointe…