6 papers
Covariance spectrum of MAXI J1820+070: On the nature of the Comptonizing flow
Shuai-Kang Yang, Bei You, Niek Bollemeijer +8
We present an analysis of the covariance spectrum of the black hole X-ray binary MAXI J1820+070 during its hard state. For the first time, we extend coherence and covariance studie…
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,…
Variable QPO lags and reduced coherence between the disc and corona in MAXI J1820+070
Niek Bollemeijer, Phil Uttley
Quasi-periodic oscillations (QPOs) are observed in the hard state of many black hole X-ray binaries. Although their origin is unknown, they are strongly associated with the corona,…
A broadband spectral-timing study of QPOs in the bright black hole X-ray binary Swift J1727.8-1613
Niek Bollemeijer, Phil Uttley, Bei You
Swift J1727.8-1613 went into outburst in August 2023 and was one of the brightest black hole X-ray binaries (BHXRBs) in recent years, leading to extensive observing campaigns by NI…
Reprocessing from highly ionized gas in the soft spectral state of V4641 Sgr with NuSTAR
Riley M. T. Connors, Joey Neilsen, Aarran W. Shaw +6
V4641 Sgr is a low-mass black hole X-ray binary system with somewhat puzzling spectral characteristics during its soft state. Recent high-resolution spectroscopic studies of V4641…