Publications (117)
Super-Eddington Accretion Geometry: a Remarkable Stability of the Hidden Ultraluminous X-Ray Source Cygnus X-3
Romana Mikušincová, Alexandra Veledina, Fabio Muleri +112
We report on the average and orbital phase-resolved polarization of Cyg X-3 in the hard state during the 2023 Imaging X-ray Polarimetry Explorer (IXPE) observational campaign. We f…
X-ray reverberation black hole mass and distance estimates of Cygnus X-1
Patrick O'Neill, Adam Ingram, Edward Nathan +4
We fit X-ray reverberation models to Rossi X-ray Timing Explorer data from the X-ray binary Cygnus X-1 in its hard state to yield estimates for the black hole mass and the distance…
X-ray Polarization of the Eastern Lobe of SS 433
Philip Kaaret, Riccardo Ferrazzoli, Stefano Silvestri +103
How astrophysical systems translate the kinetic energy of bulk motion into the acceleration of particles to very high energies is a pressing question. SS 433 is a microquasar that…
Probing the origin of quasi-periodic oscillations: the short-timescale evolution of phase lags in GRS 1915+105
Jakob van den Eijnden, Adam Ingram, Phil Uttley
We present a model-independent analysis of the short-timescale energy dependence of low frequency quasi-periodic oscillations (QPOs) in the X-ray flux of GRS 1915+105. The QPO freq…
An exact analytic treatment of propagating mass accretion rate fluctuations in X-ray binaries
Adam Ingram, Michiel van der Klis
Many statistical properties of the aperiodic variability observed in X-ray radiation from accreting compact objects can be naturally explained by the propagating fluctuations model…
Self-lensing binaries in globular clusters -- predictions for ELT
Grzegorz Wiktorowicz, Matthew Middleton, Mirek Giersz +4
Self-lensing (SL) represents a powerful technique for detecting compact objects in binary systems through gravitational microlensing effects, when a compact companion transits in f…
Modeling fast X-ray variability around an accreting black hole
Yejing Zhan, Bei You, Adam Ingram +2
X-ray inter-band time lags are observed during the outbursts of black hole X-ray binaries (BHXRBs). Timing analysis of fast variability in low Fourier frequency bands shows that hi…
Predicting the self-lensing population in optical surveys
Grzegorz Wiktorowicz, Matthew Middleton, Norman Khan +3
The vast majority of binaries containing a compact object and a regular star spend most of their time in a quiescent state where no strong interactions occur between components. De…
The high energy universe at ultra-high resolution: the power and promise of X-ray interferometry
Phil Uttley, Roland den Hartog, Cosimo Bambi +24
We propose the development of X-ray interferometry (XRI), to reveal the universe at high energies with ultra-high spatial resolution. With baselines which can be accommodated on a…
Millihertz Oscillations Near the Innermost Orbit of a Supermassive Black Hole
Megan Masterson, Erin Kara, Christos Panagiotou +22
Recent discoveries from time-domain surveys are defying our expectations for how matter accretes onto supermassive black holes (SMBHs). The increased rate of short-timescale, repet…
Tomographic reflection modelling of quasi-periodic oscillations in the black hole binary H 1743-322
Adam Ingram, Michiel van der Klis, Matthew Middleton +2
Accreting stellar mass black holes (BHs) routinely exhibit Type-C quasi-periodic oscillations (QPOs). These are often interpreted as Lense-Thirring precession of the inner accretio…
Decoding Cygnus X-2: The Critical Role of Reflection in IXPE Data
Honghui Liu, Jiachen Jiang, Adam Ingram +10
We present a spectro-polarimetric re-analysis of the first IXPE observation of Cygnus X-2 which we determine to be mainly in the normal branch, from quasi-simultaneous observations…
An IXPE-Led X-ray Spectro-Polarimetric Campaign on the Soft State of Cygnus X-1: X-ray Polarimetric Evidence for Strong Gravitational Lensing
James F. Steiner, Edward Nathan, Kun Hu +134
We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May-June. Companion multiwav…
Modelling variability in black hole binaries: linking simulations to observations
Adam Ingram, Chris Done
Black hole accretion flows show rapid X-ray variability. The Power Spectral Density (PSD) of this is typically fit by a phenomenological model of multiple Lorentzians for both the…
Type I X-ray Burst Emission Reflected into the Eclipses of EXO 0748-676
Amy H. Knight, Jakob van den Eijnden, Adam Ingram +8
The neutron star X-ray binary, EXO 0748--676, was observed regularly by the Rossi X-ray Timing Explorer (RXTE) and XMM-Newton during its first detected outburst (1985 - 2008). Thes…
General relativistic MHD simulations of non-thermal flaring in Sagittarius A*
Koushik Chatterjee, Sera Markoff, Joseph Neilsen +10
Sagittarius A* exhibits regular variability in its multiwavelength emission, including daily X-ray flares and roughly continuous near-infrared (NIR) flickering. The origin of this…
The first X-ray polarimetric observation of the black hole binary LMC X-1
Jakub Podgorny, Lorenzo Marra, Fabio Muleri +108
We report on an X-ray polarimetric observation of the high-mass X-ray binary LMC X-1 in the high/soft state, obtained by the Imaging X-ray Polarimetry Explorer (IXPE) in October 20…
The 2025 Failed Outburst of IGR J17091-3624: Spectral Evolution and the Role of Ionized Absorbers
Oluwashina K. Adegoke, Javier A. Garcia, Guglielmo Mastroserio +15
IGR J17091-3624 is the only black hole X-ray binary candidate, aside from the well-studied black hole system GRS 1915+105, observed to exhibit a wide range of structured variabilit…
An observational method for fast stochastic X-ray polarimetry-timing
Adam Ingram, Tom Maccarone
The upcoming launch of the first space based X-ray polarimeter in years will provide powerful new diagnostic information to study accreting compact objects. In particular…
Simultaneous Optical and X-ray Detection of a Thermonuclear Burst in the 2024 Outburst of EXO 0748-676
Amy H. Knight, Lauren Rhodes, Douglas J. K. Buisson +5
The neutron star low-mass X-ray binary, EXO 0748--676, recently returned to outburst after a 16 year-long quiescence. Since its return, there has been a global effort to cap…
A clean broad iron line in GS 1354--64 as seen by XRISM
Honghui Liu, Lingda Kong, Oluwashina K. Adegoke +13
We present a spectroscopic analysis of XRISM and NuSTAR observations of the black hole X-ray binary GS~1354--64 during its 2026 outburst. A total number of 3.5 million photons are…
A public relativistic transfer function model for X-ray reverberation mapping of accreting black holes
Adam Ingram, Guglielmo Mastroserio, Thomas Dauser +3
We present the publicly available model \textsc{reltrans} that calculates the light-crossing delays and energy shifts experienced by X-ray photons originally emitted close to the b…
Continuum emission from within the plunging region of black hole discs
Andrew Mummery, Adam Ingram, Shane Davis +1
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a powerful probe of the mass and spin of the central blac…
The Link Between Neutron Star X-ray Binaries and Spider Pulsars
Amy H. Knight, Adam Ingram, Jakob van den Eijnden +3
The discovery of transitional millisecond pulsars (tMSPs) provided conclusive proof that neutron star (NS) low-mass X-ray binaries (LMXBs) comprise part of the evolutionary pathway…
Self-lensing binaries as probes of Supernova physics
Grzegorz Wiktorowicz, Matthew Middleton, Aleksandra Olejak +3
Self-lensing (SL) in binary systems has the potential to provide a unique observational window into the Galactic population of compact objects. Using the and C…
X-ray Reverberation Mapping of Ark 564 using Gaussian Process Regression
Collin D. Lewin, Erin Kara, Daniel R. Wilkins +15
Ark 564 is an extreme high-Eddington Narrow-line Seyfert 1 galaxy, known for being one of the brightest, most rapidly variable soft X-ray AGN, and for having one of the lowest temp…
Cygnus X-3 revealed as a Galactic ultraluminous X-ray source by IXPE
Alexandra Veledina, Fabio Muleri, Juri Poutanen +127
The accretion of matter by compact objects can be inhibited by radiation pressure if the luminosity exceeds the critical value, known as the Eddington limit. Discovery of ultralumi…
Fourier spectral-timing techniques for the study of accreting black holes
Adam Ingram
The X-ray signal from active galactic nuclei and black hole X-ray binaries is highly variable on a range of timescales. This variability can be exploited to map the region of inter…
Persistence of the Millihertz X-ray Quasi-Periodic Oscillation in the Active Galactic Nucleus 1ES 1927+654
Megan Masterson, Erin Kara, William N. Alston +15
1ES 1927+654 is an extreme active galactic nucleus (AGN) that has defied our canonical expectations for how AGN appear across the electromagnetic spectrum and how they vary on shor…
Proof of principle X-ray reflection mass measurement of the black hole in H1743-322
Edward Nathan, Adam Ingram, James F. Steiner +9
The black hole X-ray binary H1743-322 lies in a region of the Galaxy with high extinction, and therefore it has not been possible to make a dynamical mass measurement. In this pape…
Observational signatures of disk and jet misalignment in images of accreting black holes
Koushik Chatterjee, Ziri Younsi, Matthew Liska +7
Black hole accretion is one of nature's most efficient energy extraction processes. When gas falls in, a significant fraction of its gravitational binding energy is either converte…
An X-ray reverberation mass measurement of Cygnus X-1
Guglielmo Mastroserio, Adam Ingram, Michiel van der Klis
We present the first X-ray reverberation mass measurement of a stellar-mass black hole. Accreting stellar-mass and supermassive black holes display characteristic spectral features…
Towards precision measurements of accreting black holes using X-ray reflection spectroscopy
Cosimo Bambi, Laura W. Brenneman, Thomas Dauser +14
Relativistic reflection features are commonly observed in the X-ray spectra of accreting black holes. In the presence of high quality data and with the correct astrophysical model,…
X-ray Polarization of the Black Hole X-ray Binary 4U 1630-47 Challenges Standard Thin Accretion Disk Scenario
Ajay Ratheesh, Michal DovÄiak, Henric Krawczynski +112
Large energy-dependent X-ray polarization degree is detected by the Imaging X-ray Polarimetry Explorer ({IXPE}) in the high-soft emission state of the black hole X-ray binary 4U 16…
Error formulae for the energy-dependent cross-spectrum
Adam Ingram
I present analytic error formulae for the energy-dependent cross-spectrum and rms spectrum, which are Fourier statistics widely used to probe the rapid X-ray variability observed f…
X-ray Reflection from the Plunging Region of Black Hole Accretion Disks
Jameson Dong, Guglielmo Mastroserio, Javier A. Garcıa +3
Accretion around black holes is very often characterized by distinctive X-ray reflection features (mostly, iron inner-shell transitions), which arise due to the primary radiation b…
High-density reflection spectroscopy of black hole X-ray binaries in the hard state
Honghui Liu, Jiachen Jiang, Zuobin Zhang +9
We present a high-density relativistic reflection analysis of 21 spectra of six black hole X-ray binaries in the hard state with data from \textit{NuSTAR} and \textit{Swift}. We fi…
The First X-ray Polarization Observation of the Black Hole X-ray Binary 4U 1630-47 in the Steep Power Law State
Nicole Rodriguez Cavero, Lorenzo Marra, Henric Krawczynski +107
The Imaging X-ray Polarimetry Explorer (IXPE) observed the black hole X-ray binary 4U 1630-47 in the steep power law (or very high) state. The observations reveal a linear polariza…
Phase-resolved spectroscopy of a quasi-periodic oscillation in the black hole X-ray binary GRS 1915+105 with NICER and NuSTAR
Edward Nathan, Adam Ingram, Jeroen Homan +6
Quasi-periodic oscillations (QPOs) are often present in the X-ray flux from accreting stellar-mass black holes (BHs). If they are due to relativistic (Lense-Thirring) precession of…
Accreting stellar-mass black holes
Greg Marcel, Bailey Tetarenko, Adam Ingram +3
Accreting stellar-mass black holes exhibit dramatic variability across the electromagnetic spectrum, including spectral state transitions, outbursts, and jet production, making the…
Reverberation lags viewed in hard X-rays from an accreting stellar-mass black hole
Bei You, Wei Yu, Adam Ingram +5
Accreting black holes are thought to swallow matter in the form of a disk and a hot cloud of plasma that glows brightly in X-rays, known as the corona. The X-ray emitting region is…
Characterizing the Broadband Reflection Spectrum of MAXI J1803-298 During its 2021 Outburst with NuSTAR and NICER
Oluwashina Adegoke, Javier Garcia, Riley Connors +12
MAXI J1803-298 is a transient black hole candidate discovered in May of 2021 during an outburst that lasted several months. Multiple X-ray observations reveal recurring "dipping" i…
Doppler disc tomography applied to low mass AGN spin
Matthew Middleton, Adam Ingram
Doppler tomography can provide a powerful means of determining black hole spin when our view to the central regions are revealed and obscured by optically thick orbiting material,…
Low frequency QPO spectra and Lense-Thirring precession
Adam Ingram, Chris Done, P Chris Fragile
We show that the low frequency QPO seen in the power density spectra of black hole binaries (and neutron stars) can be explained by Lense-Thirring precession. This has been propose…
Probing the Strong Gravity Region of Black Holes with eXTP
Qingcui Bu, Cosimo Bambi, Lijun Gou +42
We present the novel capabilities of the enhanced X-ray Timing and Polarimetry (eXTP) mission to study the strong gravity region around stellar-mass black holes in X-ray binary sys…
A review of quasi-periodic oscillations from black hole X-ray binaries: observation and theory
Adam Ingram, Sara Motta
Black hole and neutron star X-ray binary systems routinely show quasi-periodic oscillations (QPOs) in their X-ray flux. Despite being strong, easily measurable signals, their physi…
The Effect of Returning Radiation on Relativistic Reflection
Thomas Dauser, Javier A GarcÃa, Amy Joyce +5
We study the effect of returning radiation on the shape of the X-ray reflection spectrum in the case of thin accretion disks. We show that the returning radiation mainly influences…
X-ray quasi-periodic oscillations in Lense-Thirring precession model -- II. variability of relativistic iron K line
Bei You, Piotr T. Życki, Adam Ingram +2
Reprocessing of primary X-ray emission in the accretion disk of black hole X-ray binaries (BHXRBs) produces the reflection spectrum, with the characteristic Fe K fluorescence l…
Fitting transients with discs (FitTeD): a public light curve and spectral fitting package based on evolving relativistic discs
Andrew Mummery, Edward Nathan, Adam Ingram +1
We present FitTeD, a public light curve and spectral fitting Python-package based on evolving relativistic discs. At its heart this package uses the solutions of the time dependent…
RTFAST-Spectra: Emulation of X-ray reverberation mapping for active galactic nuclei
Benjamin Ricketts, Daniela Huppenkothen, Matteo Lucchini +4
Bayesian analysis has begun to be more widely adopted in X-ray spectroscopy, but it has largely been constrained to relatively simple physical models due to limitations in X-ray mo…
ESA Voyage 2050 white paper: A Polarized View of the Hot and Violent Universe
Paolo Soffitta, Niccolò Bucciantini, Eugene Churazov +27
Since the birth of X-ray Astronomy, spectacular advances have been seen in the imaging, spectroscopic and timing studies of the hot and violent X-ray Universe, and further leaps fo…
The effect of frame dragging on the iron K alpha line in X-ray binaries
Adam Ingram, Chris Done
The clear characteristic timescale picked out by the low frequency quasi-periodic oscillations (QPOs) seen in many black hole and neutron star binaries has the potential to provide…
Testing theories of accretion and gravity with super-extremal Kerr discs
Andrew Mummery, Steven Balbus, Adam Ingram
Fitting the thermal continuum emission of accreting black holes observed across X-ray bands represents one of the principle means of constraining the properties (mass and spin) of…
Investigating the impact of vertically extended coronae on X-ray reverberation mapping
Matteo Lucchini, Guglielmo Mastroserio, Jingyi Wang +9
Accreting black holes commonly exhibit hard X-ray emission, originating from a region of hot plasma near the central engine referred to as the corona. The origin and geometry of th…
Formation of Precessing Jets by Tilted Black-hole Discs in 3D General Relativistic MHD Simulations
Matthew Liska, Casper Hesp, Alexander Tchekhovskoy +3
Gas falling into a black hole (BH) from large distances is unaware of BH spin direction, and misalignment between the accretion disc and BH spin is expected to be common. However,…
A rapid black hole spin or emission from the plunging region?
Andrew Mummery, Jiachen Jiang, Adam Ingram +2
Emission from within the plunging region of black hole accretion flows has recently been detected in two X-ray binary systems. There is, furthermore, a possible discrepancy between…
Solutions to the relativistic precession model
Adam Ingram, Sara Motta
The relativistic precession model (RPM) can be used to obtain a precise measurement of the mass and spin of a black hole when the appropriate set of quasi periodic oscillations is…
The very high X-ray polarisation of accreting black hole IGRJ17091-3624 in the hard state
Melissa Ewing, Maxime Parra, Guglielmo Mastroserio +26
We report the first detection of the X-ray polarisation of the transient black hole X-ray binary IGRJ17091-3624 taken with the Imaging X-ray polarimetry Explorer (IXPE) in March 20…
Multi-timescale reverberation mapping of Mrk 335
Guglielmo Mastroserio, Adam Ingram, Michiel van der Klis
Time lags due to X-ray reverberation have been detected in several Seyfert galaxies. The different travel time between reflected and directly observed rays naturally causes this ty…
Highly-coherent quasi-periodic oscillations in the 'heartbeat' black hole X-ray binary IGR J17091-3624
Jingyi Wang, Erin Kara, Jeroen Homan +13
IGR J17091-3624 is a black hole X-ray binary (BHXB), often referred to as the 'twin' of GRS 1915+105 because it is the only other known BHXB that can show exotic 'heartbeat'-like v…
Variability of X-ray polarization of Cyg X-1
Vadim Kravtsov, Anastasiia Bocharova, Alexandra Veledina +31
We present the results of a three-year X-ray, optical, and radio polarimetric monitoring campaign of the prototypical black hole X-ray binary Cyg X-1, conducted from 2022 to 2024.…
Detection of X-ray Polarization from the Blazar 1ES 1959+650 with the Imaging X-ray Polarimetry Explorer
Manel Errando, Ioannis Liodakis, Alan P. Marscher +142
Observations of linear polarization in the 2-8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions g…
Evidence for a dynamic corona in the short-term time lags of black hole X-ray binary MAXI J1820+070
Niek Bollemeijer, Phil Uttley, Arkadip Basak +19
In X-ray observations of hard state black hole X-ray binaries, rapid variations in accretion disc and coronal power-law emission are correlated and show Fourier-frequency-dependent…
Disk, Corona, Jet Connection in the Intermediate State of MAXI J1820+070 Revealed by NICER Spectral-Timing Analysis
Jingyi Wang, Guglielmo Mastroserio, Erin Kara +14
We analyze 5 epochs of NICER data of the black hole X-ray binary MAXI J1820+070 during the bright hard-to-soft state transition in its 2018 outburst with both reflection spectrosco…
Modelling correlated variability in accreting black holes: the effect of high density and variable ionisation on reverberation lags
Guglielmo Mastroserio, Adam Ingram, Jingyi Wang +9
We present a new release of the RELTRANS model to fit the complex cross-spectrum of accreting black holes as a function of energy. The model accounts for continuum lags and reverbe…
The Luminous, Hard State Can't Be MAD
P. Chris Fragile, Koushik Chatterjee, Adam Ingram +1
We present a straightforward argument for why the luminous, hard state of black hole X-ray binaries (BHXRBs) cannot always be associated with a magnetically arrested accretion disc…
X-ray polarimetry-timing
Adam Ingram
X-ray polarimetry-timing is the characterization of rapid variability in the X-ray polarization degree and angle. As for the case of spectral-timing, it provides causal information…
Eclipse Mapping of EXO 0748-676: Evidence for a Massive Neutron Star
Amy H. Knight, Adam Ingram, Matthew Middleton +1
Determining the maximum possible neutron star (NS) mass places limits on the equation of state (EoS) of ultra-dense matter. The mass of NSs in low mass X-ray binaries can be determ…
Fundamental scaling relationships revealed in the optical light curves of tidal disruption events
Andrew Mummery, Sjoert van Velzen, Edward Nathan +4
We present fundamental scaling relationships between properties of the optical/UV light curves of tidal disruption events (TDEs) and the mass of the black hole that disrupted the s…
Discovery of strongly variable X-ray polarization in the neutron star low-mass X-ray binary transient XTE J1701462
Massimo Cocchi, Andrea Gnarini, Sergio Fabiani +105
After about 16 years since its first outburst, the transient neutron star low-mass X-ray binary XTE J1701462 turned on again in September 2022, allowing for the first study of i…
Dramatic Drop in the X-Ray Polarization of Swift J1727.81613 in the Soft Spectral State
JiÅÃ Svoboda, Michal DovÄiak, James F. Steiner +34
Black-hole X-ray binaries exhibit different spectral and timing properties in different accretion states. The X-ray outburst of a recently discovered and extraordinarily bright sou…
Broadband aperiodic variability in X-ray pulsars: accretion rate fluctuations propagating under the influence of viscous diffusion
Alexander A. Mushtukov, Galina V. Lipunova, Adam Ingram +3
We investigate aperiodic X-ray flux variability in accreting highly magnetized neutron stars - X-ray pulsars (XRPs). The X-ray variability is largely determined by mass accretion r…
Tilted, warped, and eccentric disks
P. Chris Fragile, Adam Ingram, Gibwa Musoke +1
We review some of the interesting consequences that tilts, warps, and eccentricities can introduce into the dynamics, thermodynamics, and observational appearance of accreting syst…
The X-ray Polarization Probe mission concept
Keith Jahoda, Henric Krawczynski, Fabian Kislat +100
The X-ray Polarization Probe (XPP) is a second generation X-ray polarimeter following up on the Imaging X-ray Polarimetry Explorer (IXPE). The XPP will offer true broadband polarim…
Reflecting on naked singularities: iron line fitting as a probe of the cosmic censorship conjecture
Andrew Mummery, Adam Ingram
We demonstrate that the X-ray iron line fitting technique can be leveraged as a powerful probe of the cosmic censorship conjecture. We do this by extending existing emission line m…
Tracking the X-ray Polarization of the Black Hole Transient Swift J1727.8-1613 during a State Transition
Adam Ingram, Niek Bollemeijer, Alexandra Veledina +120
We report on an observational campaign on the bright black hole X-ray binary Swift J1727.81613 centered around five observations by the Imaging X-ray Polarimetry Explorer (IXPE)…
Propagating mass accretion rate fluctuations in X-ray binaries under the influence of viscous diffusion
Alexander A. Mushtukov, Adam Ingram, Michiel van der Klis
Many statistical properties of X-ray aperiodic variability from accreting compact objects can be explained by the propagating fluctuations model applied to the accretion disc. The…
Population synthesis predictions of the Galactic compact binary gravitational wave foreground detectable by LISA
Jake McMillan, Adam Ingram, Cordelia Dashwood Brown +4
We use population synthesis modelling to predict the gravitational wave (GW) signal that the Laser Interferometer Space Antenna (LISA) will detect from the Galactic population of c…
The First X-Ray Polarimetry of an Eclipsing Low-Mass X-Ray Binary: Serendipitous IXPE Observation of AX J1745.6-2901
Romana Mikušincová, Lorenzo Marra, Hemanth Manikantan +38
We present the first X-ray polarimetric measurement of the neutron star low-mass X-ray binary system AX J1745.6-2901 conducted by the Imaging X-ray Polarimetry Explorer (IXPE) sate…
Modelling the Multiwavelength Variability of Mrk 335 using Gaussian Processes
Ryan-Rhys Griffiths, Jiachen Jiang, Douglas J. K. Buisson +12
The optical and UV variability of the majority of AGN may be related to the reprocessing of rapidly-changing X-ray emission from a more compact region near the central black hole.…
Implementing and Verifying a Fourier Domain Approach to Fast Stochastic X-ray Polarimetry Timing
Melissa Ewing, Adam Ingram, John Rankin +1
The launch of the Imaging X-ray Polarimetry Explorer (IXPE), the first space-based polarimeter since 1978, offers a two order of magnitude improvement to the measurement of X-ray p…
The 2022 Outburst of IGR J17091-3624: Connecting the exotic GRS 1915+105 to standard black hole X-ray binaries
Jingyi Wang, Erin Kara, Javier A. GarcÃa +13
While the standard X-ray variability of black hole X-ray binaries (BHXBs) is stochastic and noisy, there are two known BHXBs that exhibit exotic `heartbeat'-like variability in the…
Timing properties of ULX pulsars: optically thick envelopes and outflows
Alexander A. Mushtukov, Adam Ingram, Matthew Middleton +2
It has recently been discovered that a fraction of ultra-luminous X-ray sources (ULXs) exhibit X-ray pulsations, and are therefore powered by super-Eddington accretion onto magneti…
Discovery of Strong Energy-Dependent X-ray Polarization in the Intermediate State of GS 1354-64
Swati Ravi, Lorenzo Marra, James F. Steiner +20
We report the discovery of significant X-ray polarization from the dynamically confirmed black hole X-ray binary (BHXB) GS 1354-64 during its 2025-2026 outburst, obtained with the…
Optically thick envelopes around ULXs powered by accreating neutron stars
Alexander A. Mushtukov, Valery F. Suleimanov, Sergey S. Tsygankov +1
Magnetized neutron stars power at least some ultra-luminous X-ray sources. The accretion flow in these cases is interrupted at the magnetospheric radius and then reaches the surfac…
Accretion in Strong Field Gravity with eXTP
Alessandra De Rosa, Phil Uttley, Lijun Gou +99
In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related to accretion flows in the strong field gravity regime around…
X-ray polarization evidence for a 200 years-old flare of Sgr A
Frédéric Marin, Eugene Churazov, Ildar Khabibullin +101
The center of the Milky Way Galaxy hosts a 4 million solar mass black hole (Sgr A) that is currently very quiescent with a luminosity many orders of magnitude below those…
Multi-timescale X-ray reverberation mapping of accreting black holes
Guglielmo Mastroserio, Adam Ingram, Michiel van der Klis
Accreting black holes show characteristic reflection features in their X-ray spectrum, including an iron K line, resulting from hard X-ray continuum photons illuminating the ac…
A unified Lense-Thirring precession model for optical and X-ray quasi-periodic oscillations in black hole binaries
Alexandra Veledina, Juri Poutanen, Adam Ingram
Recent observations of accreting black holes reveal the presence of quasi-periodic oscillations (QPO) in the optical power density spectra. The corresponding oscillation periods ma…
A physical interpretation of the variability power spectral components in accreting neutron stars
Adam Ingram, Chris Done
We propose a physical framework for interpreting the characteristic frequencies seen in the broad band power spectra from black hole and neutron star binaries. We use the truncated…
A remarkably stable accretion disc in the Seyfert galaxy MCG-5-23-16
Roberto Serafinelli, Andrea Marinucci, Alessandra De Rosa +12
MCG-5-23-16 is a Seyfert 1.9 galaxy at redshift z=0.00849. We analyse here the X-ray spectra obtained with XMM-Newton and NuSTAR data, which are the first contemporaneous observati…
A self-lensing binary massive black hole interpretation of quasi-periodic eruptions
Adam Ingram, Sara Motta, Suzanne Aigrain +1
Binary supermassive black hole (SMBH) systems result from galaxy mergers, and will eventually coalesce due to gravitational wave (GW) emission if the binary separation can be reduc…
Modelling aperiodic X-ray variability in black hole binaries as propagating mass accretion rate fluctuations: a short review
Adam Ingram
Black hole binary systems can emit very bright and rapidly varying X-ray signals when material from the companion accretes onto the black hole, liberating huge amounts of gravitati…
The statistical properties of the cross spectrum
Edward J. R. Nathan, Adam Ingram, Daniela Huppenkothen +2
The cross spectrum encodes the correlated variability between two time signals. In recent years, the cross spectrum has been used to study astronomical sources, particularly in the…
STROBE-X: X-ray Timing and Spectroscopy on Dynamical Timescales from Microseconds to Years
Paul S. Ray, Zaven Arzoumanian, David Ballantyne +155
We present the Spectroscopic Time-Resolving Observatory for Broadband Energy X-rays (STROBE-X), a probe-class mission concept selected for study by NASA. It combines huge collectin…
DAO: A New and Public Non-Relativistic Reflection Model
Yimin Huang, Honghui Liu, Cosimo Bambi +4
We present a new non-relativistic reflection model, DAO, designed to calculate reflection spectra in the rest frame of accretion disks in X-ray binaries and active galactic nuclei.…
Energy spectra of X-ray quasi-periodic oscillations in the Lense-Thirring precession model
Piotr T. Zycki, Chris Done, Adam Ingram
We model the energy dependence of a quasi periodic oscillation (QPOs) produced by Lense-Thirring precession of a hot inner flow. We use a fully 3-dimensional Monte-Carlo code to co…
A quasi-periodic modulation of the iron line centroid energy in the black hole binary H 1743-322
Adam Ingram, Michiel van der Klis, Matthew Middleton +5
Accreting stellar-mass black holes often show a `Type-C' quasi-periodic oscillation (QPO) in their X-ray flux, and an iron emission line in their X-ray spectrum. The iron line is g…
A systematic study of the phase difference between QPO harmonics in black hole X-ray binaries
Iris de Ruiter, Jakob van den Eijnden, Adam Ingram +1
We perform a systematic study of the evolution of the waveform of black hole X-ray binary low-frequency QPOs, by measuring the phase difference between their fundamental and harmon…
Polarimetric properties of Event Horizon Telescope targets from ALMA
Ciriaco Goddi, Ivan Marti-Vidal, Hugo Messias +31
We present the results from a full polarization study carried out with ALMA during the first VLBI campaign, which was conducted in Apr 2017 in the 3mm and 1.3mm bands, in c…