Article
Astronomy & Astrophysics
M. Zhou, V Grinberg, Q-C Bu, A. Santangelo, F. Cangemi, C. M. Diez, O. Koenig, L. Ji, M. A. Nowak, K. Pottschmidt, J. Rodriguez, J. Wilms, S. Zhang, J-L Qu, S-N Zhang
Summary: By analyzing the spectral-timing properties of Cygnus X-1, the first discovered black hole binary, we find that it exhibits different spectral states and timing properties at different energy ranges. These results are important for understanding accretion phenomena and state transition mechanisms in extreme gravity fields.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Yash Bhargava, Nandini Hazra, A. R. Rao, Ranjeev Misra, Dipankar Bhattacharya, Jayashree Roy, Md Shah Alam
Summary: This study analyses the aperiodic flaring features observed in Cyg X-1, measuring the truncation of the inner accretion disc and studying the movement of the inner edge. The research discusses possible mechanisms causing these phenomena.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
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
Unnati Kashyap, Manoneeta Chakraborty, Sudip Bhattacharyya, Biki Ram
Summary: We present a broad-band investigation of the Z-type neutron star low mass X-ray binary GX 349+2, using AstroSat and NICER. We observe large scale variability in its normal branch and flaring branch, as well as moderate evolution during NICER observations. The power spectra exhibit very low-frequency noise, low-frequency noise/flaring branch noise, and can be described by a power law and evolving Lorentzian. Our findings provide insights into the origin and energy dependence of these variability components, as well as their correlation with the spectral state.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Ankur Kushwaha, V. K. Agrawal, Anuj Nandi
Summary: In this study, detailed spectral and timing analysis of Cygnus X-1 was conducted using multi-epoch observations with AstroSat. It was found that the source exhibited the softest state during high-soft state observations in 2017, and the black hole is maximally rotating. Monte Carlo simulations were conducted to estimate the uncertainty in the spin parameter, which was constrained with high confidence level.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
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
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
R. Iaria, A. Sanna, T. Di Salvo, A. F. Gambino, S. M. Mazzola, A. Riggio, A. Marino, L. Burderi
Summary: The compact binary system XB 1916-053 harbors a neutron star with a 50-minute orbital period, exhibiting positive and negative superhumps and suggesting the presence of a tilted elliptic accretion disk. Spectroscopic observations reveal prominent absorption lines from an ionized absorber along the line of sight. By extending the baseline of orbital ephemeris through new Chandra observations, it was possible to exclude some models explaining dip arrival times and obtain a better understanding of the system's characteristics.
ASTRONOMY & ASTROPHYSICS
(2021)
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
F. Cangemi, J. Rodriguez, V. Grinberg, R. Belmont, P. Laurent, J. Wilms
Summary: The X-ray spectra of X-ray binaries are dominated by emission of either soft or hard X-rays, defining their spectral states. Cygnus X-3 exhibits complex behavior with unique spectral states, especially in the hard X/soft gamma-ray emission range. This study aims to explore these spectra using the INTEGRAL database and reveals the presence of an additional nonthermal component above 50 keV in the hardest states.
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
Donna L. dePolo, Richard M. Plotkin, James C. A. Miller-Jones, Jay Strader, Thomas J. Maccarone, Tyrone N. O'Doherty, Laura Chomiuk, Elena Gallo
Summary: This study presents the results of a radio monitoring campaign of A0620 - 00, one of the best-studied and least-luminous known quiescent black hole X-ray binaries. The observations reveal significant variability in the radio emission of A0620 - 00, and the comparison with V404 Cyg suggests that less luminous jets are less variable in quiescence.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
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
G. Panizo-Espinar, M. Armas Padilla, T. Munoz-Darias, K. I. I. Koljonen, V. A. Cuneo, J. Sanchez-Sierras, D. Mata Sanchez, J. Casares, J. Corral-Santana, R. P. Fender, F. Jimenez-Ibarra, G. Ponti, D. Steeghs, M. A. P. Torres
Summary: This study presents spectroscopic observations of the low mass X-ray binary, MAXI J1348-630, during its bright outburst. The authors found evidence of a cold accretion disc wind in the system, which was similar to those seen in other X-ray transients.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Ce Cai, Shao-Lin Xiong, Wang-Chen Xue, Yi Zhao, Shuo Xiao, Qi-Bin Yi, Zhi-Wei Guo, Jia-Cong Liu, Yan-Qiu Zhang, Chao Zheng, Sheng-Lun Xie, Yan-Qi Du, Xiao-Yun Zhao, Cheng-Kui Li, Ping Wang, Wen-Xi Peng, Shi-Jie Zheng, Li-Ming Song, Xin-Qiao Li, Xiang-Yang Wen, Fan Zhang
Summary: Searching for X-ray and gamma-ray bursts, including GRBs, SGRs, and high energy transients associated with GW events or FRBs, is important. A Poisson-based search method is proposed to deal with weak bursts. Monte Carlo simulations show that the Poisson-based search method has advantages over the Gaussian case, especially for weak bursts. The Poisson-based search can provide higher significance than the Gaussian-based search for very weak bursts.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Pu Du, Shuo Zhai, Jian-Min Wang
Summary: Reverberation mapping (RM) is widely used to study the physics of broad-line regions (BLRs) in active galactic nuclei (AGNs). This paper investigates the influence of BLR densities on RM behaviors using a locally optimally emitting cloud model. The results reveal that rarefied BLRs may exhibit anomalous responses, different BLR densities can affect the correlations between time lags and equivalent widths of emission lines, and variations in BLR densities can explain changes in time lags in individual objects for different years.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Yan-Rong Li, Jian-Min Wang
Summary: Spectroastrometry is a method of measuring astrometry of sources based on wavelength/velocity variations. It can be used to study the broad-line regions (BLRs) of active galactic nuclei (AGNs), providing a new diagnostic tool for mapping BLR kinematics and geometry. This study presents a mathematical formalism for spectroastrometric reverberation mapping (RM) and demonstrates its potential in resolving BLR properties. A Bayesian framework is developed to analyze spectroastrometric data and infer the central black hole mass and angular-size distance of the BLR.
ASTROPHYSICAL JOURNAL
(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
J. Q. Peng, S. Zhang, Y. P. Chen, L. D. Kong, P. J. Wang, S. N. Zhang, L. Ji, L. Tao, J. L. Qu, M. Y. Ge, Q. C. Shui, J. Li, Z. Chang, Z. S. Li, Y. X. Xiao
Summary: We study the spectral and temporal properties of the black hole X-ray transient binary MAXI J1820+070 during the 2018 outburst with Insight-HXMT observations. The outburst of MAXI J1820+070 can be divided into three intervals. For the two intervals of the outburst, low-energy photons lag high-energy ones, while in the decay of the outburst, high-energy photons lag low-energy photons, both with a time-scale of the order of days. Relevant analysis reveals the evolution scenario of corona.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Xue-Feng Lu, Li-Ming Song, Ming-Yu Ge, You-Li Tuo, Shuang-Nan Zhang, Jin-Lu Qu, Ce Cai, Sheng-Lun Xie, Cong-Zhan Liu, Cheng-Kui Li, Yu-Cong Fu, Ying-Chen Xu, Tian-Ming Li
Summary: On April 27, 2020, the soft gamma-ray repeater SGR J1935+2154 experienced another intense outburst. Insight-HXMT conducted a one-month observation of the source, detecting a total of 75 bursts and accumulating persistent emission data. The spin period search result and the phase distribution of burst start times and burst photon arrival times were analyzed for both Insight-HXMT and Fermi/Gamma-ray Burst Monitor (GBM). It was found that the distribution of burst start times is uniform within its spin phase, while the phase distribution of burst photons is dependent on the burst's energy spectrum.
RESEARCH IN ASTRONOMY AND ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
G. Q. Ding, J. L. Qu, L. M. Song, Y. Huang, S. Zhang, Q. C. Bu, M. Y. Ge, X. B. Li, L. Tao, X. Ma, Y. P. Chen, L. Zhang, W. M. Yan, Y. L. Tuo, Y. C. Fu, S. H. Xiao, Z. X. Yang, H. X. Liu
Summary: Using observations from Insight-HXMT, the presence of hard X-ray tails in the spectra of Scorpius X-1 from 2017 to 2020 was investigated. The tails were found throughout the Z-track on the hardness-intensity diagram and became harder and weaker as the source moved from the horizontal branch to the flaring branch. A comparison with Cyg X-1 revealed that Sco X-1 does not exhibit a high-energy cutoff in its hard X-ray spectrum. The hard X-ray tails in the horizontal and normal branches can be explained by the Comptonization of photons from the neutron star surface, but further study is needed for the tails in the flaring branch.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Yu-Yang Songsheng, Jian-Min Wang
Summary: Pairs of supermassive black holes (SMBHs) at different stages are the natural result of galaxy mergers in the hierarchical framework of galaxy formation and evolution. Recent advancements in spatial resolutions have provided new opportunities to identify close binaries of SMBHs (CB-SMBHs) with sub-parsec separations through spectroastrometry (SA) observations. The distinctive structures of the differential phase curves of CB-SMBHs with two independent broad-line regions (BLRs) can help in their identification and eventually resolve them as sources of nanohertz gravitational waves.
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
S. M. Jia, J. L. Qu, F. J. Lu, L. Zhang, S. N. Zhang, L. M. Song, S. Zhang, Y. Huang, X. Ma, L. Tao, H. X. Liu, W. Yu
Summary: We analyzed the NBOs observed in two Z sources using NICER data and found the presence of pivot energy and phase jump in Cyg X-2, as well as a positive phase lag in lower energy photons. For Sco X-1, a pivot energy and phase shift were detected for the first time. These results suggest that NBO signal is associated with two different spectral components, and the emission below or above 1.5 keV is mainly related to Comptonization of the transition layer. An accretion rate change can cause a phase jump and mixing of the two Comptonization components leads to a phase shift.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Yu-Cong Fu, L. M. Song, G. Q. Ding, M. Y. Ge, Y. L. Tuo, S. Zhang, S. N. Zhang, X. Hou, J. L. Qu, J. Zhang, L. Zhang, Q. C. Bu, Y. Huang, X. Ma, X. Zhou, W. M. Yan, Z. X. Yang, X. F. Lu, T. M. Li, Y. C. Xu, P. J. Wang, S. H. Xiao, H. X. Liu, X. Q. Ren, Y. F. Du, Q. X. Zhao, Y. X. Xiao
Summary: We present an analysis of the X-ray pulsations of EXO 2030+375 during its 2021 outburst using Insight-HXMT observations. Based on the accretion torque model, we investigate the relationship between the spin frequency derivatives and the luminosity. Pulsations are detected in the energy range of 1-160 keV. The pulse profile undergoes significant changes with increasing luminosity, revealing a transition between the supercritical and subcritical accretion modes. Our results suggest the presence of multipole magnetic fields in the neutron star, with inferred magnetic field strengths ranging from (0.41 - 0.74) x 10(12) to (2.4 - 4.3) x 10(13) G.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Viraja C. Khatu, Sarah C. Gallagher, Keith Horne, Edward M. Cackett, Chen Hu, Pu Du, Jian-Min Wang, Wei-Hao Bian, Jin-Ming Bai, Yong-Jie Chen, Patrick Hall, Bo-Wei Jiang, Sha-Sha Li, Yan-Rong Li, Sofia Pasquini, Yu-Yang Songsheng, Chan Wang, Ming Xiao, Zhe Yu
Summary: Measuring broad emission-line widths in AGNs is challenging due to flux variability, especially in low signal-to-noise ratio, narrow profiles, and low spectral resolution. We analyzed the emission-line measurements of Mrk 142 obtained from two telescopes and found disparities in the measured broad-line widths. By fixing the narrow-line flux ratios, we improved the measurement accuracy of the broad-line widths in the lower-resolution spectra.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC
(2023)
Article
Nuclear Science & Technology
Hai-Sheng Zhao, Ming-Yu Ge, Xiao-Bo Li, Lin-Li Yan, You-Li Tuo, Fang-Jun Lu, Li-Ming Song, Cong-Zhan Liu, Shu Zhang, Shuang-Nan Zhang
Summary: By analyzing the observational data obtained by HXMT, the study investigates the long-term evolution of X-ray flux from the Crab pulsar. The results show a linear correlation between X-ray luminosity and spin-down luminosity, suggesting a close connection between the two. The study also indicates the stability of the high energy X-ray telescope onboard HXMT.
RADIATION DETECTION TECHNOLOGY AND METHODS
(2023)