12 citations · 55 across the 17 of their papers we have counts for
18 papers
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…
Discovery of a 9.67-s pulsar in an ultraluminous X-ray source in NGC 4631 with XMM-Newton
L. Ducci, S. Mereghetti, F. Pintore +4
Thanks to a recent observation with XMM-Newton, we discovered periodic pulsations at P= 9.6652 +/- 0.0002 s in a new ultraluminous X-ray source (ULX) in the galaxy NGC 4631. This s…
Unveiling the nature of donor stars of ULXs in NGC 1559
S. Allak, A. Akyuz
X-ray data provide insights into accretion processes and the compact objects of ultraluminous X-ray sources (ULXs), while optical and infrared (IR) observations help identify the d…
New Transient ULX Candidate in NGC 4254: Evidence of Circumbinary Disk?
Sinan Allak
This paper presents the identification of a new transient ULX candidate (ULX-3) with reaching a peak luminosity of ~ 4e39 erg/s in NGC 4254 by using archival Chandra, Swift X-Ray T…
Comprehensive X-ray and Multiwavelength Study of ULXs in NGC 1566
Sinan Allak
This paper presents a comprehensive X-ray and multi-wavelength study of ultraluminous X-ray sources (ULXs) in NGC 1566 using archival Chandra, Swift/XRT, James Webb Space Telescope…
The First Glimpse of ULXs Through the Near-Infrared Images Captured by the James Webb Space Telescope
Sinan Allak
This work presents the first results of near-infrared (NIR) counterparts of ultraluminous X-ray sources (ULXs) in the case of NGC 1672 by using James Webb Space Telescope (JWST) ob…
Investigation of the Connection Between X-ray Binaries and Compact Star Clusters in NGC 628
Senay Avdan, Aysun Akyuz, Seda Acar +3
We investigated for a possible connection between the types of X-ray binaries (XRBs) and the properties of compact star clusters in the nearby galaxy NGC 628. Using {\it Chandra} a…
Possible optical counterparts of ULXs in NGC 1672
S. Allak, A. Akyuz, E. Sonbas +1
In this study, we use archival data from HST, Chandra, XMM-Newton, and Swift-XRT, to probe the nature of 9 (X1-X9) candidate ULXs in NGC 1672. Our study focuses on using the precis…
Optical Counterparts of ULXs in NGC 1672
S. Allak, A. Akyuz, E. Sonbas +1
In this work, we deploy archival data from {\it HST}, {\it Chandra}, {\it XMM-Newton}, and {\it Swift-XRT}, to probe the nature of 9 candidate ULXs in NGC 1672. Specifically, our s…
Detection of 125.5-day Optical Periodic Modulation of the Neutron Star M51 ULX-8
S. Allak
Studying Ultraluminous X-ray sources (ULXs) in the optical wavelengths provides important clues about the accretion mechanisms and the evolutionary processes of X-ray binary system…
The Transient Ultra-luminous X-ray Source, ULX-4, in M51
S. Allak, A. Akyuz, İ. Akkaya Oralhan +6
We present the results of a temporal and spectral analysis of the transient source ULX-4 in the galaxy M51. The data used were drawn from Chandra, XMM-Newton and Swift-XRT archives…
Optical Counterparts of ULXs in Two Dwarf Galaxies: NGC 4861 and NGC 4449
M. Ozdogan Ela, A. Akyuz, N. Aksaker +7
We present the results of a search for optical candidates of Ultraluminous X-ray sources (ULXs) in two dwarf galaxies: NGC 4861 and NGC 4449 using Hubble Space Telescope {\it HST}…
Çukurova University Space Sciences and Solar Energy Research and Application Center (UZAYMER): I. Observing Conditions and Ongoing Projects
Arif Solmaz, Nazım Aksaker, Aysun Akyüz +6
Çukurova University Space Sciences and Solar Energy Research and Application Center (UZAYMER) was founded in 1991. In this work, we present current research in the fields of astron…
Identification of a New Ultraluminous X-ray Source in NGC 1316
S. Allak, A. Akyuz, N. Aksaker +3
In this study, we report identification of a new ultraluminous X-ray source (ULX) named as X-7 in NGC 1316, with an unabsorbed luminosity of 2.110 erg s using…