Article
Astronomy & Astrophysics
Shu Niu, Fu-Guo Xie, Q. Daniel Wang, Li Ji, Feng Yuan, Min Long
Summary: Despite advances in our understanding of LLAGNs, we still lack fundamental details about the mechanisms of radiation and flare/outburst in hot accretion flow. By analyzing the X-ray data of nearby LLAGN M81*, we find that the X-ray continuum emission likely originates from inverse Compton scattering in the hot accretion flow and flares are rare in M81*. Based on a comparison with Sgr A* and M31*, we propose a magnetohydrodynamical model to universally understand flares in LLAGNs when considering differences in accretion rate and black hole mass.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
H. Avdan, E. Sonbas, K. S. Dhuga, A. Vinokurov, E. Goegues, S. Avdan, Y. N. Solovyeva, A. E. Kostenkov, E. S. Shablovinskaya, D. Goktas
Summary: Archival data from XMM-Newton, Chandra, and Hubble Space Telescope were used to study the X-ray and optical properties of two ultraluminous X-ray sources in NGC 4536. Improved astrometry between Chandra and HST allowed for the detection of optical counterparts for both sources. Ground-based optical spectra were obtained with the BTA Telescope to complement the archival data.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. Allak, A. Akyuz, I. Akkaya Oralhan, S. Avdan, N. Aksaker, A. Vinokurov, F. Soydugan, E. Sonbas, K. S. Dhuga
Summary: In this study, we analyzed the ULX-4 transient source in the M51 galaxy using temporal and spectral analysis techniques. The X-ray flux of the source showed significant variation within a month, but no short-term variability was observed within the time intervals of 100-2000 s. We found evidence of a bi-modality feature in the flux distribution of ULX-4. Based on optical counterparts identified using Hubble Space Telescope data, the spectral type of ULX-4 was determined to be B-type stars. One of the counterparts exhibited a weak periodicity, which could be associated with orbital motion of a red supergiant donor or interactions with a circumstellar disc in the case of a Be/X star.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Roberto Soria, Mari Kolehmainen, Alister W. Graham, Douglas A. Swartz, Mihoko Yukita, Christian Motch, Thomas H. Jarrett, James C. A. Miller-Jones, Richard M. Plotkin, Thomas J. Maccarone, Laura Ferrarese, Alexander Guest, Ariane Lancon
Summary: In this study, we analyze the population of ultraluminous X-ray sources (ULXs) in late-type galaxies in the Virgo cluster. We find that the ULX luminosity function is related to the mass and star formation rate of the galaxies, and we tentatively identify the most luminous X-ray source as a recent supernova or its remnant.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
K. Kouroumpatzakis, A. Zezas, A. Wolter, A. Fruscione, K. Anastasopoulou, A. Prestwich
Summary: This systematic study of the metallicity variations within the collisional ring galaxy NGC922 reveals a difference in metallicity between star-forming regions in the bulge and the ring. The study also shows an anticorrelation between X-ray luminosity and metallicity of the sub-galactic regions of NGC922.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
M. Ozdogan Ela, A. Akyuz, N. Aksaker, S. Avdan, I. Akkaya Oralhan, A. Vinokurov, S. Allak, Y. Solovyeva, K. Atapin, D. Bizyaev
Summary: The study uses archival data from the Hubble Space Telescope to search for optical candidates of ultraluminous X-ray sources in two dwarf galaxies, confirming associations with young star groups and HII complexes. The X-ray spectral data suggest that the sources are in luminous hard states, consistent with long-term observations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
S. Allak, A. Akyuz, E. Sonbas, K. S. Dhuga
Summary: This study utilizes archival data from various telescopes to investigate the nature of nine candidate ultraluminous X-ray sources in NGC 1672. The study focuses on using precise source positions to identify optical counterparts for these sources. Optical counterparts are found for two of the candidates, while two potential counterparts are found for three other candidates. No optical counterparts are found for the remaining four sources. The study also provides insights into the spectral properties and variability of the sources.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
G. Riccio, M. Paolillo, M. Cantiello, R. D'Abrusco, X. Jin, Z. Li, T. Puzia, S. Mieske, D. J. Prole, E. Iodice, G. D'Ago, M. Gatto, M. Spavone
Summary: In this study, the intra-cluster population of low-mass X-ray binaries (LMXB) residing in globular clusters (GC) in the Fornax galaxy cluster were investigated. The results showed that LMXBs tend to form in red and bright GCs. The likelihood of a red GC hosting an LMXB decreases with galactocentric distance, while bright LMXBs are deficient in blue intra-cluster GCs. The spectral properties of GC-LMXBs were also found to differ between intra-cluster and host-galaxy samples.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Sara Saeedi, Manami Sasaki
Summary: In this study, observations with XMM-Newton in the field of the Sculptor dwarf spheroidal galaxy were analysed to classify the X-ray sources. The results revealed the presence of numerous background X-ray sources and identified stars, galaxies, and candidates within this galaxy.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Fabio Pintore, S. Motta, C. Pinto, M. G. Bernardini, G. Rodriguez-Castillo, R. Salvaterra, G. L. Israel, P. Esposito, E. Ambrosi, C. Salvaggio, L. Zampieri, A. Wolter
Summary: The research looked at the spectral and temporal properties of NGC 4559 X7, finding flux variations and flaring activity. Narrow absorption and emission lines were detected, suggesting the presence of outflows. Additionally, hard and soft lags were measured, potentially due to the influence of accretion flows.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
S. Avdan, A. Akyuz, S. Acar, I. Akkaya Oralhan, S. Allak, N. Aksaker
Summary: We investigated the connection between types of X-ray binaries (XRBs) and the properties of compact star clusters in NGC 628. Using Chandra data, we detected 75 X-ray sources, including 69 XRBs and one ultraluminous X-ray source. We identified optical counterparts for 15 XRBs and classified them as high-mass XRBs (HMXBs), while the others were classified as low-mass XRBs (LMXBs). We also identified and analyzed 864 compact star clusters in NGC 628, finding that HMXBs are associated with younger clusters and LMXBs with older clusters.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
H. Stiele, A. K. H. Kong
Summary: We investigated the evolution of quasi-periodic oscillations (QPOs) and noise components using power-density spectra in five snapshots of NICER observations of the black hole transient GX 339-4 during its transition from the hard state to the soft state. We found a strong correlation between the hardness ratio and the type of QPO observed, suggesting a connection between the accretion geometry and spectral properties. We also observed that the type-B QPO undergoes a decoherence process during the transition between different states.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Chiara Salvaggio, A. Wolter, A. Belfiore, M. Colpi
Summary: We analyzed all available Chandra observations of the Cartwheel galaxy and its compact group from 2001 to 2008. Our main focus was on the variability in the X-ray band of this collisional ring galaxy. We specifically studied point-like sources, with a particular interest in ultraluminous X-ray sources (ULXs), and found that about one-third of the sources showed long-term variability.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
D. J. Walton, A. D. A. Mackenzie, H. Gully, N. R. Patel, T. P. Roberts, H. P. Earnshaw, S. Mateos
Summary: The study presents a new catalogue of ULX candidates based on recent data releases from three X-ray observatories, identifying new extreme ULX candidate NGC3044 ULX1. The catalogue includes 1843 ULX candidates associated with 951 host galaxies and is expected to be a valuable resource for future observations of ULXs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Arran C. Gross, Andrea Prestwich, Philip Kaaret
Summary: Lyman continuum and line emission play important roles in the reionization of the early Universe. Haro 11 is a local galaxy where Ly alpha and continuum emission can escape without being absorbed, potentially due to feedback from X-ray sources. Spatial analysis reveals dynamic variability and flux changes in X1 and X2 sources.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)