Related papers: Limits on spin determination from disc spectral fi…

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, and can provide an independent estimate that does not suffer…

We present the results of a NuSTAR study of the dynamically confirmed stellar-mass black hole GS 1354-645. The source was observed during its 2015 "hard" state outburst; we concentrate on spectra from two relatively bright phases. In the…

Black hole X-ray binaries (BHXRBs) play a crucial role in understanding the accretion of matter onto a black hole. Here, we focus on exploring the transient BHXRB \source~discovered by Swift/BAT and MAXI/GSC during its January 2019…

The Galactic Black hole candidate XTE J1752-223 was observed during the decay of its 2009 outburst with the Suzaku and XMM-Newton observatories. The observed spectra are consistent with the source being in the ''intermediate`` and…

The fluorescent iron Ka line is a powerful observational probe of the inner regions of black holes accretion disks. Previous studies have assumed that only material outside the radius of marginal stability can contribute to the observed…

We report on the spectroscopic analysis of the black hole binary GX 339-4 during its recent 2017-2018 outburst, observed simultaneously by the Swift and NuSTAR observatories. Although during this particular outburst the source failed to…

Recently, the accretion geometry of the black-hole X-ray binary Cyg X-1 was probed with the X-ray polarization. The position angle of the X-ray emitting flow was found to be aligned with the position angle of the radio jet in the plane of…

Sagittarius A* (Sgr A*) exhibits frequent flaring activity across the electromagnetic spectrum, often associated with a localized region of strong emission, known as a hot spot. We aim to establish an empirical relationship linking key…

We analyzed simultaneous archival XMM-Newton and RXTE observations of the X-ray binary and black hole candidate Swift J1753.5-0127. In a previous analysis of the same data a soft thermal component was found in the X-ray spectrum, and the…

We show the softest ever spectrum from Cyg~X-1, detected in 2013 with Suzaku. This has the weakest high energy Compton tail ever seen from this object, so should give the cleanest view of the underlying disk spectrum, and hence the best…

Disc accretion on to a black hole is often misaligned from its spin axis. If the disc maintains a significant magnetic field normal to its local plane, we show that dipole radiation from Lense-Thirring precessing disc annuli can extract a…

We present a high density disc reflection spectral analysis of a sample of 17 Seyfert 1 galaxies to study the inner disc densities at different black hole mass scales and accretion rates. All the available XMM-Newton observations in the…

We investigate properties of iron fluorescent line arising as a result of illumination of a black hole accretion disc by an X-ray source located above the disc surface. We study in details the light-bending model of variability of the line,…

We present 3-50 keV NuSTAR observations of the AGN Mrk 335 in a very low flux state. The spectrum is dominated by very strong features at the energies of the iron line at 5-7 keV and Compton hump from 10-30 keV. The source is variable…

We compare X-ray emission from several general relativistic, multi-frequency, radiation magnetohydrodynamic simulations of thin black hole accretion disks with different accretion rates and spins. The simulations were performed using the M1…

Using recent results from numerical relativity simulations of black hole mergers, we revisit previous studies of cosmological black hole spin evolution. We show that mergers are very unlikely to yield large spins, unless alignment of the…

Radiation from a narrow circular ring shows a characteristic double-horn profile dominated by photons having energy around the maximum or minimum of the allowed range, i.e. near the extremal values of the energy shift. The energy span of a…

We have explored spectral line profiles due to spiral patterns in accretion discs around black holes. A parametrization was employed for the shape and emissivity of spiral waves, which can be produced by non-axisymmetric perturbations…

We present the analysis of several observations of the black hole binary GX 339--4 during its bright intermediate states from two different outbursts (2002 and 2004), as observed by RXTE/PCA. We perform a consistent study of its reflection…

We describe a model that generates first order adiabatic EMRI waveforms for quasi-circular equatorial inspirals of compact objects into rapidly rotating (near-extremal) black holes. Using our model, we show that LISA could measure the spin…