Article
Astronomy & Astrophysics
Norman Khan, Matthew J. Middleton
Summary: The NASA Swift telescope has been observing transients and target-of-opportunity with a focus on ULXs for the last 20 years. Simultaneous data from the XRT and UVOT have been obtained for the majority of these observations, allowing for the study of coupled variability. Through a sample of 40 ULXs with repeat observations, stacked images are extracted to analyze the spatial extent of UV/optical emission and long-term light curves to investigate correlations between UV and X-ray emission. The results suggest weakly correlated joint variability for a subset of ULXs and nonlinear relationships for other sources, requiring further analysis or higher quality data to accurately understand the nature of the emission.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Alexander A. Mushtukov, Simon Portegies Zwart, Sergey S. Tsygankov, Dmitrij Nagirner, Juri Poutanen
Summary: The discovery of pulsating ultraluminous X-ray sources (ULXs) indicates that the apparent luminosity of accreting neutron stars can exceed the Eddington luminosity by a factor of 100s. The relationship between actual and apparent luminosity in ULXs is still debated. A large pulsed fraction is a typical feature of discovered pulsating ULXs. Using Monte Carlo simulations, it is argued that strong beaming and high pulsed fraction largely exclude each other in ULXs. This suggests that pulsating ULXs are not strongly beamed and their apparent luminosity is close to the actual one.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Norman Khan, Matthew J. Middleton, Grzegorz Wiktorowicz, Thomas Dauser, Timothy P. Roberts, Joern Wilms
Summary: The discovery of neutron stars powering ultraluminous X-ray sources raises questions about the underlying population, with this paper incorporating a model to estimate the relative number of visible ULXs based on various factors such as the abundance of black holes or neutron stars. By comparing data from XMM-Newton and predicting the impact of the eROSITA all-sky survey, the study aims to constrain the underlying demographic and provide insights into the nature of these phenomena.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Steven Fahlman, Rodrigo Fernandez
Summary: In this study, we modified the solver to simulate accretion discs and found that a significant amount of mass ejection can occur during the evolution of accretion discs around black hole remnants. The velocity distribution and electron fraction distribution of the ejected mass exhibit characteristic features.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Alessandro Paduano, Arash Bahramian, James C. A. Miller-Jones, Adela Kawka, Fabian Goettgens, Jay Strader, Laura Chomiuk, Sebastian Kamann, Stefan Dreizler, Craig O. Heinke, Tim-Oliver Husser, Thomas J. Maccarone, Evangelia Tremou, Yue Zhao
Summary: The Galactic globular cluster NGC 3201 has been observed to host stellar-mass black holes, and the radio and X-ray emissions from these black holes are found to be very weak, indicating a low accretion rate. Additionally, analysis of multiple wavelengths reveals new sources and provides insight into the sub-subgiant population.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Yan Li, Erlin Qiao, Rong-Feng Shen
Summary: The study explores the possibility of a single black hole, binary neutron stars, or a binary system of a neutron star and a white dwarf as the unseen companion of the red giant V723 Mon. It suggests that the single black hole scenario is the most likely, and calculates the synchrotron emission caused by the interaction of the compact companion with the wind.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Tiger Yu-Yang Hsiao, Tomotsugu Goto, Tetsuya Hashimoto, Daryl Joe D. Santos, Alvina Y. L. On, Ece Kilerci-Eser, Yi Hang Valerie Wong, Seong Jin Kim, Cossas K-W Wu, Simon C-C Ho, Ting-Yi Lu
Summary: The study discusses the effectiveness of building a Dyson sphere around a black hole, concluding that by collecting different energy sources, a Type II civilization can be sustained. Additionally, measuring spectral energy distributions and radial velocity variations may aid in identifying potential artificial structures.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Roberto Soria, Ruican Ma, Lian Tao, Shuang-Nan Zhang
Summary: By revisiting the published results of X-ray and optical studies on the black hole candidate MAXI J0637-430, we have improved the understanding of its system parameters. This black hole is the farthest known from the Galactic Center and has the shortest period among all Galactic black hole X-ray binaries.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
R. Taverna, L. Marra, S. Bianchi, M. Dovciak, R. Goosmann, F. Marin, G. Matt, W. Zhang
Summary: Studying the radiation emitted from black hole accretion discs is crucial in understanding the physical properties of black holes, particularly their spin. In addition to spectral analysis, polarimetry is becoming increasingly important and can provide estimates of black hole spin. Absorption effects have a significant impact on the polarization properties of the emitted radiation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
A. Gurpide, O. Godet, F. Koliopanos, N. Webb, J-F Olive
Summary: By studying the long-term X-ray spectral evolution of ULXs, we find that the hardest sources in our sample may be powered by strongly magnetised NSs, while softer sources may be explained by weakly magnetised NSs or BHs.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Gurpide, O. Godet, G. Vasilopoulos, N. A. Webb, J-F Olive
Summary: The study demonstrates a clear and recurrent evolutionary pattern in the HID of Holmberg II X-1 and NGC 5204 X-1, characterized by distinct spectral regimes and transitions. Both sources show similarities in hosting the same type of accretor and/or accretion flow geometry, with the spectral changes likely attributed to periodic mass-transfer rate increases and narrowing of super-critical funnels. Further investigation is needed to understand the aperiodic variability and longer periodicity observed in these ULX sources.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
A. Bahramian, C. O. Heinke, J. A. Kennea, T. J. Maccarone, P. A. Evans, R. Wijnands, N. Degenaar, J. J. M. in't Zand, A. W. Shaw, L. E. Rivera Sandoval, S. McClure, A. J. Tetarenko, J. Strader, E. Kuulkers, G. R. Sivakoff
Summary: The study reveals that a large subset of very faint X-ray transients (VFXTs) is likely composed of symbiotic systems, with some newly discovered hard transients likely being VFXT X-ray binaries.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Pranav Nagarajan, Kareem El-Badry, Antonio C. Rodriguez, Jan Van Roestel, Benjamin Roulston
Summary: We conducted multi-epoch spectroscopic follow-up of ellipsoidal variables identified as candidates for hosting quiescent black holes (BHs) and neutron stars (NSs) based on Gaia Data Release 3 (DR3). We obtained spectra for 14 of the most promising targets and derived minimum companion masses of 0.5 M-? in all cases. Our findings suggest that these systems likely do not contain BHs or NSs, and we propose alternative explanations for the observed variability.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Middleton, A. Gurpide, D. J. Walton
Summary: We explore the predicted luminosity changes of ultraluminous X-ray sources (ULXs) when the disc is locally supercritical and find that significant parameter space in dipole field strength and accretion rate can result in changes of less than an order of magnitude in luminosity. We identify three ULXs (IC 342 X-1, Cir ULX-5, and NGC 1313 X-1) that exhibit changes consistent with the super-Eddington systems entering a propeller state, and estimate the dipole field strength of NGC 1313 X-1 to be < 10^10 G. This study suggests that searching for changes in hardness ratio and at high energies is the most reliable method to identify potential propeller states.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Hanna Sai, Xiaofeng Wang, Jianfeng Wu, Jie Lin, Hua Feng, Tianmeng Zhang, Wenxiong Li, Jujia Zhang, Jun Mo, Tianrui Sun, Shuhrat A. Ehgamberdiev, Davron Mirzaqulov, Liming Rui, Weili Lin, Xulin Zhao, Han Lin, Jicheng Zhang, Xinghan Zhang, Yong Zhao, Xue Li, Danfeng Xiang, Lingzhi Wang, Chengyuan Wu
Summary: MAXI J1820+070 is a low-mass black hole X-ray binary system with high luminosity in both optical and X-ray bands during outburst periods. Optical emission precedes X-ray emission by 20.80 +/- 2.85 days during the rebrightening process. The optical flux is influenced by the X-ray irradiation model and additional energy sources.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Samaresh Mondal, Krzysztof Belczynski, Grzegorz Wiktorowicz, Jean-Pierre Lasota, Andrew R. King
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2020)
Article
Astronomy & Astrophysics
J-M Hameury, C. Knigge, J-P Lasota, F-J Hambsch, R. James
ASTRONOMY & ASTROPHYSICS
(2020)
Article
Astronomy & Astrophysics
J. -M. Hameury, J. -P. Lasota
ASTRONOMY & ASTROPHYSICS
(2020)
Article
Astronomy & Astrophysics
F. H. Vincent, M. Wielgus, M. A. Abramowicz, E. Gourgoulhon, J-P Lasota, T. Paumard, G. Perrin
Summary: Researchers aim to develop a simple analytic disk model for the accretion flow of M87* to predict its image, assuming it is a Kerr black hole or an alternative compact object. They computed synchrotron emission from the disk model and carried out numerical fits to the EHT data, showing that alternatives to the Kerr spacetime may provide similar results and further observations are needed to test the Kerr paradigm conclusively.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
J-M Hameury, J-P Lasota
Summary: The disc instability model can explain most properties of dwarf novae and soft X-ray transients, but phenomena like rebrightenings in WZ Sge stars remain unexplained. By analyzing a specific system and making adjustments to the model, researchers were able to account for the observed rebrightenings in the light curves.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Grzegorz Wiktorowicz, Jean-Pierre Lasota, Krzysztof Belczynski, Youjun Lu, Jifeng Liu, Krystian Ilkiewicz
Summary: ULXs are important for astrophysics due to their extreme luminosities, but their nature is still poorly understood. They are believed to be a diverse group of objects, such as low-mass X-ray binaries, high-mass X-ray binaries, and possibly systems with intermediate-mass black holes. Observational data on ULX donors could enhance our understanding of these systems, but only a few have been identified, mainly red supergiants. Further research is needed to investigate the connection between ULXs and red supergiants.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
K. Belczynski, A. Romagnolo, A. Olejak, J. Klencki, D. Chattopadhyay, S. Stevenson, M. Coleman Miller, J-P Lasota, Paul A. Crowther
Summary: Using the detections of double black hole mergers from the LIGO/Virgo gravitational-wave observatories, recent studies have compared the formation channels between isolated binaries and dense stellar clusters, and proposed the existence of primordial black holes in the population. However, due to the uncertainties in key aspects of binary stellar evolution, the conclusions drawn from these studies are not yet robust.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Colin Littlefield, Jean-Pierre Lasota, Jean-Marie Hameury, Simone Scaringi, Peter Garnavich, Paula Szkody, Mark Kennedy, McKenna Leichty
Summary: This study reports the 27 day TESS light curve of V1025 Cen, an intermediate polar (IP) that exhibits 12 bursts of extremely short and repetitive accretion, validating the magnetically gated accretion mechanism in magnetized white dwarfs proposed by Spruit and Taam.
ASTROPHYSICAL JOURNAL LETTERS
(2022)
Article
Astronomy & Astrophysics
Jessymol K. Thomas, Philip A. Charles, David A. H. Buckley, Marissa M. Kotze, Jean-Pierre Lasota, Stephen B. Potter, James F. Steiner, John A. Paice
Summary: This study investigates the optical and X-ray light curves of the black hole X-ray transient MAXIJ1820 + 070, revealing its significant changes in optical brightness, modulation, and inner disc geometry. The unprecedentedly large amplitude modulation observed in this transient requires a warp in the disc, potentially driven by irradiation.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
J. -M. Hameury, J. -P. Lasota, A. W. Shaw
Summary: This study examines the short outburst characteristics of V1223 Sgr, an intermediate polar, and compares them with the predictions of the magnetospheric gating model. The results indicate that the model accounts well for the observed outburst duration and intensity, but the model assumptions need further improvement and validation.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Multidisciplinary Sciences
S. Scaringi, P. J. Groot, C. Knigge, A. J. Bird, E. Breedt, D. A. H. Buckley, Y. Cavecchi, N. D. Degenaar, D. de Martino, C. Done, M. Fratta, K. Itkiewicz, E. Koerding, J-P Lasota, C. Littlefield, C. F. Manara, M. O'Brien, P. Szkody, F. X. Timmes
Summary: Unexplained rapid bursts have been observed from TV Columbae and other accreting systems, resembling classical nova explosions and type-I X-ray bursts.
Article
Astronomy & Astrophysics
S. Scaringi, P. J. Groot, C. Knigge, J-P Lasota, D. de Martino, Y. Cavecchi, D. A. H. Buckley, M. E. Camisassa
Summary: Rapid bursts at optical wavelengths, known as micronovae, have been observed in accreting white dwarfs. These bursts can cause a significant increase in optical luminosity, up to a factor of 30, within an hour, before fading on time-scales of several hours. There is evidence to suggest that these bursts may be the result of localized thermonuclear runaways triggered by magnetic confinement of accretion streams on to the white dwarfs. The proposed model seems to favor magnetic systems with high white dwarf mass and high mass-transfer rate.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jean-Pierre Lasota, Andrew King
Summary: Magnetar models fail to explain the behavior of ultraluminous X-ray sources. ULXs may be explained by radiation beaming caused by accretion disc winds.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
A. Olejak, M. Fishbach, K. Belczynski, D. E. Holz, J-P Lasota, M. C. Miller, T. Bulik
ASTROPHYSICAL JOURNAL LETTERS
(2020)
