381 citations · 1.5k across the 23 of their papers we have counts for
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Long-term X-ray spectral evolution of Ultraluminous X-ray sources: implications on the accretion flow geometry and the nature of the accretor
Andrés Gúrpide, Olivier Godet, Filippos Koliopanos +2
The discovery of pulsations in several Ultraluminous X-ray sources (ULXs) demonstrated that a fraction of ULXs are powered by super-Eddington accretion onto neutron stars (NSs). Th…
Chandra probes the X-ray variability of M51 ULX-7: evidence of propeller transition and X-ray dips on orbital periods
G. Vasilopoulos, F. Koliopanos, F. Haberl +4
We report on the temporal properties of the ULX pulsar M51 ULX-7 inferred from the analysis of the 2018-2020 Swift/XRT monitoring data and archival Chandra data obtained over a per…
Discovery of a ~30-Year-Duration Post-Nova Pulsating Supersoft Source in the Large Magellanic Cloud
G. Vasilopoulos, F. Koliopanos, T. E. Woods +3
Supersoft X-ray sources (SSS) have been identified as white dwarfs accreting from binary companions and undergoing nuclear-burning of the accreted material on their surface. Althou…
The XMM-Newton serendipitous survey. X: The second source catalogue from overlapping XMM-Newton observations and its long-term variable content
I. Traulsen, A. D. Schwope, G. Lamer +12
The XMM-Newton Survey Science Centre Consortium (SSC) develops software in close collaboration with the Science Operations Centre to perform a pipeline analysis of all XMM-Newton o…
The XMM-Newton serendipitous survey IX. The fourth XMM-Newton serendipitous source catalogue
N. A. Webb, M. Coriat, I. Traulsen +28
Sky surveys produce enormous quantities of data on extensive regions of the sky. The easiest way to access this information is through catalogues of standardised data products. {\e…
NuSTAR X-ray spectrum of Be-X-ray pulsar Swift J1845.7-0037: Bulk and thermal Comptonization of cyclotron seed photons in the accretion column
Filippos Koliopanos, Georgios Vasilopoulos, Michael T. Wolff
Aims: Spectral and temporal analysis of the NuSTAR observation Galactic Be-XRB Swift J1845.7-0037. during its recent outburst. Methods: For the spectral analysis we use both phenom…
The chemical composition of the accretion disk and donor star in Ultra Compact X-ray Binaries: A comprehensive X-ray analysis
Filippos Koliopanos, Mathias Peault, Georgios Vasilopoulos +1
We have analyzed the X-ray spectra of all known Ultra Compact X-ray Binaries (UCXBs), with the purpose of constraining the chemical composition of their accretion disk and donor st…
Disappearance of the Fe K emission line in Ultra Compact X-ray Binaries 4U 1543-624 and Swift J1756.9-2508
Filippos Koliopanos, Georgios Vasilopoulos, Sebastien Guillot +1
We investigate the long-term variability of the K line of iron in the spectra of two Ultra Compact X-ray Sources (UCXBs) with C/O-rich donors. We revisit archival observations b…
M51 ULX-7: super-orbital periodicity and constraints on the neutron star magnetic field
G. Vasilopoulos, S. K. Lander, F. Koliopanos +1
In the current work we explore the applicability of standard theoretical models of accretion to the observed properties of M51 ULX-7. The spin-up rate and observed X-ray luminosity…
NGC 300 ULX1: spin evolution, super-Eddington accretion and outflows
G. Vasilopoulos, M. Petropoulou, F. Koliopanos +4
NGC300 ULX1 is an ultra-luminous X-ray pulsar, showing an unprecedented spin evolution, from about 126 s to less than 20 s in only 4 years, consistent with steady mass accretion ra…
Investigating ULX accretion flows and cyclotron resonance in NGC 300 ULX1
Filippos Koliopanos, Georgios Vasilopoulos, Johannes Buchner +2
Methods. We analyzed broadband XMM-Newton and NuSTAR observations of NGC 300 ULX1, performing phase-averaged and phase-resolved spectroscopy. We compared two physically motivated m…
The XMM-Newton serendipitous survey. VIII: The first XMM-Newton serendipitous source catalogue from overlapping observations
I. Traulsen, A. D. Schwope, G. Lamer +13
XMM-Newton has observed the X-ray sky since early 2000. The XMM-Newton Survey Science Centre Consortium has published catalogues of X-ray and ultraviolet sources found serendipitou…
Accreting, highly magnetized neutron stars at the Eddington limit: A study of the 2016 outburst of SMC X-3
Filippos Koliopanos, Georgios Vasilopoulos
We study the temporal and spectral characteristics of SMC X-3 during its 2016 outburst. To probe accretion onto highly magnetized neutron stars (NSs), at the Eddington limit. We ob…
ULX spectra revisited: Accreting, highly magnetized neutron stars as the engines of ultraluminous X-ray sources
Filippos Koliopanos, Georgios Vasilopoulos, Olivier Godet +3
Aims: In light of recent discoveries of pulsating ULXs and recently introduced models, that propose neutron stars (NSs) as the central engines of ULXs, we revisit the (XMM-Newton a…
Luminosity dependent change of the emission diagram in the X-ray pulsar 4U 1626-67
Filippos Koliopanos, Marat Gilfanov
We detect variability of the Fe Ka emission line in the spectrum of X-ray pulsar 4U 1626-67, correlated with changes in its luminosity and in the shape of its pulse profile. Analys…
The XMM-Newton serendipitous survey. VII. The third XMM-Newton serendipitous source catalogue
S. R. Rosen, N. A. Webb, M. G. Watson +37
Thanks to the large collecting area (3 x ~1500 cm at 1.5 keV) and wide field of view (30' across in full field mode) of the X-ray cameras on board the European Space Agency X-r…
X-ray diagnostics of chemical composition of the accretion disk and donor star in UCXBs II: XMM-Newton observations
Filippos Koliopanos, Marat Gilfanov, Lars Bildsten +1
We search for the Fe K line in spectra of Ultra Compact X-ray Binaries (UCXBs). For this purpose we have analyzed XMM-Newton observations of five confirmed UCXBs. We find that t…
X-ray diagnostics of chemical composition of the accretion disk and donor star in ultra-compact X-ray binaries
Filippos Koliopanos, Marat Gilfanov, Lars Bildsten
Non-solar composition of the donor star in ultra-compact X-ray binaries may have a pronounced effect on the fluorescent lines appearing in their spectra due to reprocessing of prim…