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The advent of the new generation of X-ray telescopes yielded a significant step forward in our understanding of ionised absorption generated in the accretion discs of X-ray binaries. It has become evident that these relatively weak and…
Ultraluminous X-ray sources are non-nuclear point sources exceeding the Eddington luminosity of a 10 Solar mass black hole. Modern consensus for a majority of the ULX population is that they are powered by stellar-mass black holes or…
High velocity outflows from supermassive black holes have been invoked to explain the recent identification of strong absorption features in the hard X-ray spectra of several quasars. Here, Monte Carlo radiative transfer calculations are…
The surface flux (and the corresponding observed flux) of a geometrically thick ``funnel'' shaped disk is computed taking into account the radiation impinging on the surface from other parts of the disk. It is found that the ratio of the…
Aims. Soft X-ray excesses have been detected in several Be/X-ray binaries and interpreted as the signature of hard X-ray reprocessing in the inner accretion disk. The system XMMU J054134.7-682550, located in the LMC, featured a giant Type…
Giant radio pulses (GRPs) are sporadic bursts emitted by some pulsars, lasting a few microseconds. GRPs are hundreds to thousands of times brighter than regular pulses from these sources. The only GRP-associated emission outside radio…
The Imaging X-ray Polarimetry Explorer (IXPE) observations of the X-ray binary 4U 1630-47 in the high soft state revealed high linear polarization degrees (PDs) rising from 6% at 2 keV to 10% at 8 keV. We discuss in this letter three…
Transitional millisecond pulsars provide a unique set of observational data for understanding accretion at low rates onto magnetized neutron stars. In particular, PSR~J1023+0038 exhibits a remarkable bimodality of the X-ray luminosity (low…
Recent advances in X-ray spectroscopic observation have enabled researchers to reveal distinct clumpy structures in the super-Eddington outflows from the supermassive black hole in PDS 456 (XRISM Collaboration 2025), initiating detailed…
Ultraluminous pulsars are a definite proof that persistent super-Eddington accretion occurs in nature. They support the scenario according to which most Ultraluminous X-ray Sources (ULXs) are super-Eddington accretors of stellar mass rather…
We study the evolution of binary systems of Ultra-luminous X-ray sources and compute their optical emission assuming accretion onto a black hole via a non standard, advection-dominated slim disc with an outflow. We consider systems with…
Circumstellar discs with large dust depleted cavities and vigorous accretion onto the central star are often considered signposts for (multiple) giant planet formation. In this letter we show that X-ray photoevaporation operating in discs…
By analyzing the Rossi X-ray Timing Explorer data on SAX J1808.4-3658 we show that the X-ray emission in accretion powered millisecond pulsars can be produced by Comptonization in a hot slab (radiative shock) of Thomson optical depth tau~1…
We present calculations of the time lags and the coherence function of X-ray photons for a novel model of radiation emission from accretion powered, high-energy sources. Our model involves only Comptonization of soft photons injected near…
We compute the X-ray spectra produced by non-static coronae atop accretion discs around black holes and neutron stars. The hot corona is radiatively coupled to the underlying disc (the reflector) and generates an X-ray spectrum which is…
Polarization measurements provide strong constraints on models for emission from rotation-powered pulsars. We present multiwavelength polarization predictions showing that measurements over a range of frequencies can be particularly…
Recurring outbursts associated with matter flowing onto compact stellar remnants (black-holes, neutron stars, white dwarfs) in close binary systems, provide strong test beds for constraining the poorly understood accretion process. The…
We employ our new model for the polarised emission of accreting X-ray pulsars to describe the emission from the luminous X-ray pulsar Hercules X-1. In contrast with previous works, our model predicts the polarisation parameters…
A great deal of emphasis on timing in the RXTE era has been on pushing toward higher and higher frequency phenomena, particularly kHz QPOs. However, the large areas of the RXTE pointed instruments provide another capability which is key for…
We use the outer gap model to explain the spectrum and the energy dependent light curves of the X-ray and soft gamma-ray radiations of the spin-down powered pulsar PSR B1509-58. In the outer gap model, most pairs inside the gap are created…