12 citations · 55 across the 17 of their papers we have counts for
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A statistical hardness classification of ultraluminous X-ray sources using long-term Swift/XRT monitoring
Sinan Allak, Wei Yu, Menglei Zhou +2
We characterize long-term hardness behavior in 29 ultraluminous X-ray sources (ULXs) using over 3500 archival Swift/XRT observations. We classify observations as soft-band dominate…
Stable X-ray reverberation lags in the black hole X-ray binary Swift J1727.8-1613
Wei Yu, Sinan Allak, Zi-Xu Yang +3
Aims. We investigate the evolution of X-ray reverberation lags in the black hole X-ray binary Swift J1727.8-1613 during its 2023 outburst, with the aim of probing the inner accreti…
Spectral and timing variability of the transient ultraluminous X-ray source NGC 4631 X-4
Sinan Allak, Wei Yu, Lorenzo Ducci +4
Ultraluminous X-ray sources (ULXs) are among the best laboratories for studying super-Eddington accretion onto compact objects. We present a detailed spectral and timing analysis o…
A candidate cyclotron line at 1.89 keV in the ultraluminous X-ray source NGC 4861 X-2
Sinan Allak, Lorenzo Ducci, Valery F. Suleimanov +6
In this Letter, we report the detection of an absorption-like feature at ~1.89 keV in Chandra/ACIS spectra of the ultraluminous X-ray source NGC 4861 X-2, based on the deepest obse…
Identification of three new ultraluminous X-ray sources in NGC 4631 and NGC 1097: Evidence for stellar-mass black holes
Sinan Allak, Aysun Akyuz, Yasemin Aladag +2
Recent observations of galaxies continue to reveal new ultraluminous X-ray sources (ULXs), increasing their known population and improving the statistics needed to understand their…