Search Publications
Quasi-periodic eruptions as Lense-Thirring precession of super-Eddington flows
Pinto, C.; Miniutti, G.; Dauser, T. +9 more
Quasi-periodic eruptions (QPEs) are a recently identified class of X-ray transient associated with tidal disruption events by supermassive black holes, and for which there are multiple possible explanations. In this paper, we present a simple model which requires the black hole be spinning, be misaligned with the accretion flow (both conditions of…
Testing disc reprocessing models for AGN optical variability by comparison of X-ray and optical power spectra of NGC 4395
Dhillon, V. S.; Knapen, J. H.; Breedt, E. +11 more
It is generally thought that active galactic nucleus (AGN) optical variability is produced, at least in part, by reprocessing of central X-rays by a surrounding accretion disc, resulting in wavelength-dependent lags between bands. Any good model of AGN optical variability should explain not only these lags, but also the overall pattern of variabil…
The XMM Cluster Survey: automating the estimation of hydrostatic mass for large samples of galaxy clusters – I. Methodology, validation, and application to the SDSSRM-XCS sample
Nichol, R. C.; Romer, A. K.; Bhargava, S. +18 more
We describe features of the X-ray: Generate and Analyse (XGA) open-source software package that have been developed to facilitate automated hydrostatic mass (
The VMC Survey - LI. Classifying extragalactic sources using a probabilistic random forest supervised machine learning algorithm
Maitra, Chandreyee; Aird, James; de Grijs, Richard +10 more
We used a supervised machine learning algorithm (probabilistic random forest) to classify
Simultaneous optical and X-ray detection of a thermonuclear burst in the 2024 outburst of EXO 0748-676
Ingram, Adam; Roberts, Timothy P.; Middleton, Matthew +5 more
The neutron star low-mass X-ray binary, EXO 0748-676, recently returned to outburst after a
Reflection-dominated Compton-thick AGN candidates in the SRG/eROSITA Lockman Hole survey
Gilfanov, M. R.; Medvedev, P. S.; Sunyaev, R. A. +2 more
We search for reflection-dominated Compton-thick active galactic nuclei (CT AGN) candidates in the Lockman Hole (LH) region using the data of SRG/eROSITA LH survey. We selected sources with anomalously hard photon indices in the 0.3-8.0 keV band, untypical for Type I AGN. In particular, we required that the upper end of the 90 per cent error inter…
Mind the gaps: improved methods for the detection of periodicities in unevenly sampled data
Gúrpide, Andrés; Middleton, Matthew
The detection of periodic signals in irregularly sampled time series is a problem commonly encountered in astronomy. Traditional tools used for periodic searches, such as the periodogram, have poorly defined statistical properties under irregular sampling, which complicate inferring the underlying aperiodic variability used for hypothesis testing.…
X-ray timing and spectral characteristics of compact symmetric objects
Stalin, C. S.; Saikia, D. J.; Paliya, Vaidehi S. +1 more
Compact Symmetric Objects (CSOs) are a distinct category of jetted active galactic nuclei whose high-energy emission is not well understood. We examined the X-ray characteristics of 17 bona fide CSOs using observations from Chandra, XMM-Newton, and NuSTAR. Among the sources with XMM-Newton observations, we found two sources, J0713+4349 and J1326+3…
Accretion onto WD 2226-210, the central star of the Helix Nebula
Chu, Y. -H.; Estrada-Dorado, S.; Guerrero, M. A. +4 more
The central star of the Helix Nebula, WD 2226
Accretion disc dynamics in extragalactic black hole X-ray binaries: a comprehensive study of M33 X-7, NGC 300 X-1, and IC 10 X-1
Nandi, Anuj; Bhuvana, G. R.
Extragalactic black hole X-ray binaries (BH-XRBs) are the most intriguing X-ray sources as some of them are 'home' to the most massive stellar-mass BHs ever found. In this work, we conduct a comprehensive study of three massive, eclipsing extragalactic BH-XRBs i.e. M33X-7, NGC300X-1, and IC10X-1 and using entire X-ray observations available from X…