Related papers: A model for cyclotron resonance scattering feature…
High energies emissions observed in X-ray binaries (XRBs), active galactic nuclei (AGNs) are linearly polarized. The prominent mechanism for X-ray is the Comptonization process. We revisit the theory for polarization in Compton scattering…
We develop a Monte Carlo Comptonization model for the X-ray spectrum of accretion-powered pulsars. Simple, spherical, thermal Comptonization models give harder spectra for higher optical depth, while the observational data from Vela X-1…
In the framework of the magnetar model for the Soft Gamma Repeaters and Anomalous X-ray Pulsars, we consider the structure of neutron star magnetospheres threaded by large-scale electrical currents. We construct self-similar, force-free…
We conduct a parameter survey of neutron star accretion column simulations by solving the relativistic radiation MHD equations with opacities that account for strong magnetic fields and pair production. We study how column properties depend…
Motivated by the report by Cottam et al. (2002) of iron resonance scattering lines in the spectra of thermonuclear bursts from EXO 0748-676, we have investigated the information about neutron star structure and the geometry of the emission…
We aim to investigate the energy-resolved pulse profile changes of the accreting X-ray pulsar V 0332+53, focusing in the cyclotron line energy range, using the full set of available NuSTAR observations. We applied a tailored pipeline to…
We compute rest-frame reflection spectra and the corresponding energy-dependent linear polarization degree and angle for (un)polarized single-temperature blackbody spectra impinging on a partially ionized constant-density optically thick…
We have developed an improved model of X-ray emission from optically thin, two-temperature accretion flows, \texttt{kerrflow}, using an exact Monte Carlo treatment of global Comptonization as well as with a fully general relativistic…
We present two observations of the high-mass X-ray binary GX 301-2 with NuSTAR, taken at different orbital phases and different luminosities. We find that the continuum is well described by typical phenomenological models, like a very…
We perform Monte Carlo simulations of cosmic ray-induced hard X-ray radiation from the Earth's atmosphere. We find that the shape of the spectrum emergent from the atmosphere in the energy range 25-300 keV is mainly determined by Compton…
Spectral features can arise by reflection of coronal X-rays on a black hole accretion disc. The resulting profile bears various imprints of strong gravitational field acting on the light emitting gas. The observed shape of the reflection…
We use Monte Carlo approach to study the energetics of electrons accelerated in a pulsar polar gap. As energy-loss mechanisms we consider magnetic Compton scattering of thermal X-ray photons and curvature radiation. The results are compared…
The spectral line shapes for hydrogen-like heavy ion emitters embedded in strongly correlated two-component electron-ion plasmas are investigated with numerical simulations. For that purpose the microfield fluctuations are calculated by…
We have investigated the effects of resonant scattering of emission lines on the image morphology and intensity from coronal loop structures. It has previously been shown that line of sight effects in optically thin line emission can yield…
Estimations of magnetic fields of neutron stars, observed as radio and X-ray pulsars, are discussed. It is shown, that theoretical and observational values for different types of radiopulsars are in good correspondence. Radiopulsars in…
Diffuse soft X-ray line emission is commonly used to trace the thermal and chemical properties of the hot interstellar medium, as well as its content, in nearby galaxies. Although resonant line scattering complicates the interpretation of…
Recent optical/UV data of Geminga (Mignani et al. 1998) have strengthen the significance of the emission feature present over the thermal continuum best fitting the EUV/soft X-ray data. Here we present a phenomenological model interpreting…
Accreting X-ray pulsars (XRPs) undergo luminous X-ray outbursts during which the luminosity-dependent spectral and timing features of the neutron star's emission can be analyzed in detail, thus shedding light on the accretion regime at…
Previous works have suggested a correlation between the X-ray luminosity Lx and the rotational luminosity Lrot of the radio pulsars.However, none of the obtained regression lines are statistically acceptable due to large scatters. We…
Thomson scattering spectra measure the response of plasma particles to incident radiation. In warm dense matter, which is opaque to visible light, x-ray Thomson scattering (XRTS) enables a detailed probe of the electron distribution and has…