272 citations · 1.6k across the 43 of their papers we have counts for
9 papers · 1 filter
Modelling the energy dependencies of high-frequency QPO in black hole X-ray binaries
P. T. Zycki, A. Niedzwiecki, M. A. Sobolewska
We model energy dependencies of the quasi periodic oscillations (QPO) in the model of disc epicyclic motions, with X-ray modulation caused by varying relativistic effects. The mode…
Energy spectra of X-ray quasi-periodic oscillations in accreting black hole binaries
P. T. Zycki, M. A. Sobolewska, A. Niedzwiecki
We investigate the energy dependencies of X-ray quasi-periodic oscillations in black hole X-ray binaries. We analyze RXTE data on both the low- and high-frequency QPO. We construct…
Evolution of the X-ray Emission of Radio-Quiet Quasars
Brandon C. Kelly, Jill Bechtold, Aneta Siemiginowska +2
We report new Chandra observations of seven optically faint, z \sim 4 radio-quiet quasars. We have combined these new observations with previous Chandra observations of radio-quiet…
The iron K feature in Narrow Line Seyfert 1's: evidence for a P Cygni profile?
C. Done, M. A. Sobolewska, Marek Gierlinski +1
Narrow Line Seyfert 1 galaxies are generally accreting at high fractions of the Eddington limit. They can show complex X-ray spectra, with a strong `soft excess' below 2 keV and a…
Spectral and Fourier analyses of X-ray QPO in accreting black holes
M. A. Sobolewska, P. T. Zycki
We study energy dependencies of quasi-periodic oscillations from a number of black hole X-ray binaries. The selected sources were observed by RXTE at time periods close to state tr…
Modelling the energy dependencies of X-ray quasi-periodic oscillations in accreting compact objects
P. T. Zycki, M. Sobolewska
We have constructed models of quasi-periodic variability of X-ray emission from accreting compact objects. Assuming a general scenario of a propagation model of variability, with i…
What is the origin of the soft excess in AGN?
Malgorzata Sobolewska, Chris Done
We investigate the nature of the soft excess below 1 keV observed in AGN. We use the XMM-Newton data of the low redshift, optically bright quasar, PG 1211+143, and we compare it wi…
High redshift radio quiet quasars -- exploring parameter space of accretion models. Part II: patchy corona model
M. A. Sobolewska, A. Siemiginowska, P. T. Zycki
We modeled the spectral energy distribution (SED) of high redshift radio quiet quasars (high-z RQQs). We computed spectra in a patchy corona geometry where an accretion disk extend…
High redshift radio quiet quasars - exploring the parameter space of accretion models. Part I: hot semi-spherical flow
M. A. Sobolewska, A. Siemiginowska, P. T. Zycki
Two families of models are currently considered to describe an accretion flow onto black holes and production of the observed X-ray radiation: (1) a standard cold accretion disk wi…