Article
Astronomy & Astrophysics
N. Shakura, D. A. Kolesnikov, P. S. Medvedev, R. A. Sunyaev, M. R. Gilfanov, K. A. Postnov, S. Molkov
Summary: The eROSITA instrument observed the Her X-1/HZ Her binary system during the low state of the X-ray source, detecting orbital modulation of the X-ray flux likely resulting from scattering by different regions of the optical star.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Pavel Abolmasov, Juri Poutanen
Summary: Kilohertz-scale quasi-periodic oscillations (kHz QPOs) are a unique feature of neutron star low-mass X-ray binaries, serving as a probe for the inner accretion flow. Existing models can only explain part of their characteristics, while a simple boundary layer (BL) model can reproduce some properties, such as the parallel tracks effect, by considering the exchange of mass and angular momentum with the star on similar timescales.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Samaresh Mondal, Agata Rozanska, Patrycja Baginska, Alex Markowitz, Barbara De Marco
Summary: By analyzing multi-epoch observations, we found that Circinus ULX5 likely contains a stellar mass black hole or a neutron star, with distinctive spectral states corresponding to different flux levels.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
C. M. Diez, V Grinberg, F. Fuerst, E. Sokolova-Lapa, A. Santangelo, J. Wilms, K. Pottschmidt, S. Martinez-Nunez, C. Malacaria, P. Kretschmar
Summary: Vela X-1 is a complex binary system that provides a key understanding of high-mass X-ray binary accretion processes. This study used NuSTAR to conduct two new observations, allowing for the investigation of accretion geometry and stellar wind properties. The results confirmed anti-correlations between photon index, folding energy, and luminosity, and observed a decrease in cyclotron line energy following a strong flare. The study also found strong variability in absorption, possibly caused by a large-scale structure and variable line of sight.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Devina Misra, Konstantinos Kovlakas, Tassos Fragos, Margaret Lazzarini, Simone S. Bavera, Bret D. Lehmer, Andreas Zezas, Emmanouil Zapartas, Zepei Xing, Jeff J. Andrews, Aaron Dotter, Kyle A. Rocha, Philipp M. Srivastava, Meng Sun
Summary: This study investigates the effects of various physical assumptions on the synthetic X-ray luminosity functions (XLFs) of high-mass X-ray binaries (HMXBs). The results show an overabundance of XRBs with black hole accretors in certain model parameter combinations, leading to a discrepancy with observations. However, assumptions regarding circularization and criteria for the formation of an X-ray-emitting accretion disk around wind-accreting black holes can reduce this deviation.
ASTRONOMY & ASTROPHYSICS
(2023)
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
P. Reig, N. D. Kylafis
Summary: The study suggests that in black hole binaries, the extended jet is an excellent candidate source of hard photons, with some soft photons being reflected back to the accretion disk via inverse Compton scattering, while most of the Comptonized, back-scattered photons escape close to the black hole.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
R. Amato, A. Gurpide, N. A. Webb, O. Godet, M. J. Middleton
Summary: Through studying the X-ray spectral and temporal evolution of ULX M 81 X-6, it is found that the source oscillates between two main states, suggesting it may be caused by a neutron star (NS). However, it has a lower magnetic field strength compared to other NS-ULXs, making it unlikely to be caused by NS magnetic field torque. Therefore, further observations are needed to better understand its nature.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
S. M. Mazzola, R. Iaria, T. Di Salvo, A. Sanna, A. F. Gambino, A. Marino, E. Bozzo, C. Ferrigno, A. Riggio, A. Anitra, L. Burderi
Summary: The study analyzed the NuSTAR observation of Scorpius X-1 to investigate its spectral emission. The results showed consistent physical scenarios in the two branches of the Z track, including features like blackbody, disc-blackbody, and optically thick Comptonising corona.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
M. Armas Padilla, J. M. Corral-Santana, A. Borghese, V. A. Cuneo, T. Munoz-Darias, J. Casares, M. A. P. Torres
Summary: This study presents the first online and comprehensive catalogue of Ultracompact X-ray binaries (UCXBs), called UltraCompCAT. The catalogue includes 49 sources, including 20 confirmed UCXBs and 25 candidates. The analysis of the catalogue sample reveals the existence of at least two separate groups of UCXBs, one composed of persistent systems and the other composed of transient objects.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
G. Panizo-Espinar, T. Munoz-Darias, M. Armas Padilla, F. Jimenez-Ibarra, J. Casares, D. Mata Sanchez
Summary: The study of Aquila X-1's optical spectroscopy did not reveal clear optical wind signatures, but the strong and broad Hα emission line indicates the presence of optically thin ejecta or an extended disc atmosphere. The research also suggests that optical nebular phases may be a relatively common observational feature during the late stages of low mass X-ray binaries' outbursts.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Guoying Zhao, Zhaosheng Li, Yuanyue Pan, Maurizio Falanga, Long Ji, Yupeng Chen, Shu Zhang
Summary: Type I X-ray bursts are the result of unstable thermonuclear burning on the surface of a neutron star, resulting in the release of energetic X-ray photons. These bursts interact with the surrounding accretion disk, increasing the accretion rate. By analyzing two photospheric radius expansion bursts in 4U 1636-536, it was found that the spectral fitting can be improved by considering enhanced persistent emission or reflection from the accretion disk. Evidence suggests that both Poynting-Robertson drag and disk reflection occurred during these bursts, and the disk reflection may contribute up to 20-30% of the total burst emissions.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
L. Ducci, S. Mereghetti, A. Santangelo, L. Ji, S. Carpano, S. Covino, V Doroshenko, F. Haberl, C. Maitra, I Kreykenbohm, A. Udalski
Summary: This study reports the observations of the X-ray binary A0538-66, including its characteristics in X-rays and optical wavelengths. The observations revealed that the neutron star can accrete material considerably far from periastron, providing important new information about the plasma environment surrounding the binary system.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
A. Anitra, T. Di Salvo, R. Iaria, L. Burderi, A. F. Gambino, S. M. Mazzola, A. Marino, A. Sanna, A. Riggio
Summary: The X-ray source 4U 1822-371 is a high-inclination X-ray binary system that shows evidence of a reflection component and emission lines from various elements. The inclination angle and inner disc radius are still uncertain, and more observations are needed to confirm the results and gain further insights into this enigmatic source.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
Yu-Peng Chen, Shu Zhang, Long Ji, Shuang-Nan Zhang, Peng-Ju Wang, Ling-Da Kong, Zhi Chang, Jing-Qiang Peng, Qing-Cang Shui, Jian Li, Zhao-Sheng Li, Lian Tao, Ming-Yu Ge, Jin-Lu Qu
Summary: After 49 years of quiescence, 4U 1730-22 became active and had two outbursts in 2021 and 2022; 10 thermonuclear X-ray bursts were detected with Insight-HXMT. Among them, the faintest burst showed a double-peaked profile, placing the source as the seventh accreting neutron star (NS) exhibiting double-peaked type I X-ray bursts; the other bursts showed photospheric radius expansion (PRE). The properties of a double-peaked non-PRE burst indicate that it could be related to a stalled burning front. For the five bright PRE bursts, apart from the emission from the neutron star (NS) surface, we find the residuals both in the soft (<3 keV) and hard (>10 keV) X-ray bands. Time-resolved spectroscopy reveals that the excess can be attributed to an enhanced preburst/persistent emission or the Comptonization of the burst emission by the corona. We find, the burst emission shows a rise until the photosphere touches down to the NS surface rather than the theoretical predicted constant Eddington luminosity. The shortage of the burst emission in the early rising phase is beyond the occlusion by the disk. We speculate that the findings above are due to that the obscured part (not only the lower part) of the NS surface is exposed to the line of sight due to the evaporation of the obscured material by the burst emission, or the burst emission is anisotropic (xi > 1) in the burst early phase. In addition, based on the fluxes of PRE bursts at their touchdown times, we derive a distance estimation as 9.0-12.4 kpc.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Yu-Peng Chen, Shu Zhang, Shuang-Nan Zhang, Long Ji, Peng-Ju Wang, Ling-Da Kong, Zhi Chang, Jing-Qiang Peng, Qing-Cang Shui, Jian Li, Lian Tao, Ming-Yu Ge, Jin-Lu Qu
Summary: 4U 1730-22 had two outbursts in 2021 and 2022 after 49 years of quiescence. NICER observed the onset and tail of the outbursts, providing an excellent opportunity to study the state transition and its underlying mechanism. The research found that the accretion disk is close to the neutron star surface in the high/soft state, and a steep change in the accretion disk emission within 1 day, known as the soft-to-hard transition, may be due to the propeller effect.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Astronomy & Astrophysics
Wang-Chen Xue, Xiao-Bo Li, Shao-Lin Xiong, Yong Chen, Shuang-Nan Zhang, Li-Ming Song, Shu Zhang, Ming-Yu Ge, You-Li Tuo, Hai-Tao Li, Dao-Chun Yu, Dong-Ya Guo, Jia-Cong Liu, Yan-Qiu Zhang, Chao Zheng
Summary: The Earth occultation technique is used to construct a background model of the Crab Nebula observed by Insight-HXMT. A Bayesian atmospheric density retrieval method is proposed, which combines Poisson and Gaussian statistics. By modeling the attenuation of X-ray photons during the occultation, the neutral densities of the atmosphere at different altitude ranges are simultaneously retrieved. This method reduces potential systematic bias and maximizes the use of occultation data, resulting in improved density measurements and cross-checking of atmospheric models.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Astronomy & Astrophysics
Honghui Liu, Cosimo Bambi, Jiachen Jiang, Javier A. Garcia, Long Ji, Lingda Kong, Xiaoqin Ren, Shu Zhang, Shuangnan Zhang
Summary: We analyze the relativistic reflection spectra of GX 339-4 during its 2021 outburst and find strong relativistic reflection signatures indicating a high black hole spin and an intermediate disk inclination angle. The hard-to-soft transition is accompanied by an increasing disk temperature and a softening corona emission, while the inner disk radius remains stable. The corona height, assuming a lamppost geometry, stays close to the black hole across the state transition. Including Comptonization, the scattering fraction parameter decreases during the transition. Our analysis with a reflection model designed for hot accretion disks supports the scenario of corona property variations during the state transition.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Qing C. Shui, S. Zhang, Yu P. Chen, Shuang N. Zhang, Ling D. Kong, Peng J. Wang, L. Ji, Hong X. Yin, Jin L. Qu, L. Tao, Ming Y. Ge, Jing Q. Peng, Z. Chang, J. Li, P. Zhang
Summary: We systematically analyzed the QPO observations of H1743-322 and found consistent positive correlations between the QPO fractional rms amplitude and nonthermal fraction of the emission, independent of the outburst brightness. However, the QPO rms dependence on frequency and the coronal temperature range differed between the outburst rise and decay phases. The findings suggest a possible connection between the QPO rms differences, hysteresis traces, and corona-jet transitions in H1743-322.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
X. Ma, L. Zhang, L. Tao, Q. C. Bu, J. L. Qu, S. N. Zhang, D. K. Zhou, Y. Huang, S. M. Jia, L. M. Song, S. Zhang, M. Y. Ge, H. X. Liu, Z. X. Yang, W. Yu, E. S. Yorgancioglu
Summary: We present the X-ray timing results of MAXI J1820+070 during its 2018 outburst using Insight-HXMT and NICER observations. LFQPOs are detected in the low/hard state and the hard intermediate state, with an approximately 90-day duration. Our results show the energy dependence of LFQPO characteristics and phase lags, providing new insights into the origin of the radiation from different regions of the accretion disk and the relativistic jet.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Xi-Hong Luo, Shuo Xiao, Shi-Jie Zheng, Ming-Yu Ge, You-Li Tuo, Shao-Lin Xiong, Shuang-Nan Zhang, Fang-Jun Lu, Yue Huang, Cheng Yang, Qi-Jun Zhi, Li-Ming Song, Wen-Xi Peng, Xiang-Yang Wen, Xin-Qiao Li, Zheng-Hua An, Jin Wang, Ping Wang, Ce Cai, Cheng-Kui Li, Xiao-Bo Li, Fan Zhang, Ai-Jun Dong, Wei Xie, Jian-Chao Feng, Qing-Bo Ma, Hua Wang De, Lun-Hua Shang, Xin Xu, Meng-Xuan Zhang, Zi-Ping Dong, Shi-Jun Dang
Summary: The determination of absolute and relative spacecraft position is crucial for various purposes including operation, observations, data analysis, scientific studies, and deep-space exploration. This study presents a navigation accuracy of approximately 20 km using 16-day Crab pulsar data observed with Fermi's Gamma-ray Burst Monitor. Additionally, a new method for joint navigation using repeated bursts from magnetar SGR J1935+2154 observed by the Gravitational-wave High-energy Electromagnetic Counterpart All-sky Monitor and GBM is proposed.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Astronomy & Astrophysics
Chen Wang, Jin-Yuan Liao, Ju Guan, Yuan Liu, Cheng-Kui Li, Na Sai, Qi Luo, Jing Jin, Yi Nang, Shuang-Nan Zhang
Summary: The first X-ray source catalog of the Insight-HXMT Galactic Plane Scanning Survey (GPSS) with a sky coverage of b <10 degrees is presented. The catalog includes more than 1300 sources monitored in the 1-100 keV energy band, with 223 sources having a signal-to-noise ratio greater than 5. Flux variabilities and hardness ratios of different source types, such as X-ray binaries and supernova remnants, are analyzed. The results show that X-ray binaries exhibit higher activity and harder spectra compared to other source types.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Engineering, Aerospace
Yidi Wang, Shuangnan Zhang, Minyu Ge, Wei Zheng, Xiaoqian Chen, Shijie Zheng, Fangju Lu
Summary: The recent flight experiments with NICER and Insight-HXMT have shown the feasibility of XNAV in space. However, the current methods employed in these experiments are computationally expensive for handling Crab pulsar data. To solve this problem, a fast algorithm called XTITAN is proposed for on-orbit estimating the pulse phase of Crab pulsar. XTITAN is significantly faster than the methods used in the flight experiments, making it computationally efficient and suitable for onboard computation.
IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS
(2023)
Article
Instruments & Instrumentation
Qinyu Wu, Zhixing Ling, Chen Zhang, Quan Zhou, Xinyang Wang, Weimin Yuan, Shuang-Nan Zhang
Summary: In recent years, scientific CMOS (sCMOS) sensors have outperformed CCDs in several aspects: higher readout frame rate, higher radiation tolerance, and higher working temperature. A new method is introduced to measure the image lag of a sCMOS sensor under low-light illumination by extracting the image lag from X-ray photons. The results show that the image lag of the sensor is small and has no significant impact on the imaging quality and energy resolution.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
(2023)
Article
Astronomy & Astrophysics
Wei Yu, Qing-Cui Bu, Zi-Xu Yang, He-Xin Liu, Liang Zhang, Yue Huang, Deng-Ke Zhou, Jin-Lu Qu, Shuang-Nan Zhang, Shu Zhang, Li-Ming Song, Shu-Mei Jia, Xiang Ma, Lian Tao, Ming-Yu Ge, Qing-Zhong Liu, Jing-Zhi Yan
Summary: This paper presents a time-frequency analysis of the low-frequency quasiperiodic oscillations observed in the black hole X-ray binary MAXI J1820+070, using the Hilbert-Huang transform. The study decomposes the light curve of the quasiperiodic oscillation component and measures its phase lag and broadband noise. The results suggest a physical origin involving the internal shock model of the jet.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Yuan Feng, Ye-Fei Yuan, Shuang-Nan Zhang
Summary: The iron fluorescence emission lines from X-ray binaries and active galactic nuclei are important for studying the physical processes near the event horizon of stellar-mass black holes and supermassive black holes. This study investigated the line profile of relativistic broad iron lines from the cool accretion disk of a black hole due to asymmetric illumination from a moving corona. The results showed that the illumination and line profile depend on the position and velocity of the corona, with the flux received by the disk region below the corona being the most important factor affecting the line profiles.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Xin-Ying Song, Shuang-Nan Zhang
Summary: As the brightest gamma-ray burst ever detected, GRB 221009A may provide some insights into the hidden features of less bright bursts. The first pulse in this burst is believed to be an unconventional precursor, offering a unique case for studying precursor phenomena. By analyzing the duration and flux, we have obtained constraints on the luminosity and Lorentz factor of the weak jet.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Shuo Xiao, Jiao-Jiao Yang, Xi-Hong Luo, Shao-Lin Xiong, Yuan-Hong Qu, Shuang-Nan Zhang, Wang-Chen Xue, Xiao-Bo Li, You-Li Tuo, Ai-Jun Dong, Ru-Shuang Zhao, Shi-Jun Dang, Lun-Hua Shang, Qing-Bo Ma, Ce Cai, Jin Wang, Ping Wang, Cheng-Kui Li, Shu-Xu Yi, Zhen Zhang, Ming-Yu Ge, Shi-Jie Zheng, Li-Ming Song, Wen-Xi Peng, Xiang-Yang Wen, Xin-Qiao Li, Zheng-Hua An, Xin Xu, Yue Wang, Chao Zheng, Yan-Qiu Zhang, Jia-Cong Liu, Bin Zhang, Wei Xie, Jian-Chao Feng, De-Hua Wang, Qi-Jun Zhi
Summary: In this work, the minimum variation timescale (MVT) of X-ray bursts from SGR J1935+2154 is systematically studied. The MVTs peak at about 2 ms, supporting the magnetospheric origin in pulsar-like models. The shock radius and Lorentz factor of the jet in GRB-like models are also constrained. The MVT of the XRB associated with FRB 200428 is longer than most bursts, indicating a special radiation mechanism.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Multidisciplinary Sciences
Bei You, Xinwu Cao, Zhen Yan, Jean-Marie Hameury, Bozena Czerny, Yue Wu, Tianyu Xia, Marek Sikora, Shuang-Nan Zhang, Pu Du, Piotr T. Zycki
Summary: This study analyzes archival multiwavelength observations of the black hole x-ray binary MAXI J1820+070 in 2018 and finds evidence for the formation of a magnetically arrested disk (MAD), indicated by the delayed radio and optical fluxes compared with the x-ray flux.