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A robust model for the origin of optical quasi-periodic variability in supersoft X-ray sources

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arXiv 2022年

作者： Zhao, Weitao Meng, Xiangcun Cui, Yingzheng Liu, Zheng-Wei Yunnan Observatories Chinese Academy of Sciences 650216 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China

Context. Supersoft X-ray sources (SSSs) are known as possible progenitors of Type Ia supernovae. The quasi-periodic variability has been detected in the optical light curves of SSSs. However, the exact origin of such quasi-periodic observable features remains a mystery. Aims. In this paper, we aim to reproduce the observed optical quasi-periodic variability of SSSs by proposing a white dwarf (WD) accretion model with a periodic mass transfer caused by the irradiation of supersoft X-ray onto the companion star. Methods. Assuming that a periodic mass transfer from the companion star to the WD can be caused while the supersoft X-ray irradiates the companion star, we used MESA to simulate the WD accretion process and the subsequent WD evolution by adopting a periodic jagged accretion rate. Results. Comparing our results to the optical light curves of a well-observed SSS RX J0513.9-6951, we find that our models can reproduce the quasi-periodic transition between the optical high and low states of RX J0513.9-6951 because the periodic accretion rate can lead to the WD photosphere expands and contracts periodically in our models. In addition, we find that the transitional periods of the SSSs in our models strongly depend on the mass of the accreting WDs. The more massive the WD mass is, the shorter the transitional period. Conclusions. Based on our results, we suggest that the periodic mass transfer caused by the irradiation of supersoft X-ray onto the companion star may be the origin of the observed optical quasi-periodic variability in SSSs. In addition, our results indicate that the observed optical transition period of a SSS may be useful for the rough estimate of the mass of an accreting WD. © 2022, CC0.

关键词： White dwarfs

Investigation into the reflection properties of the neutron star low-mass X-ray binary 4U 1636-53

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Astronomy and Astrophysics 2023年 677卷

作者： Lyu, M. Zhang, G.B. Wang, H.G. García, F. Department of Physics Xiangtan University Xiangtan Hunan411105 China Key Laboratory of Stars and Interstellar Medium Xiangtan University Xiangtan Hunan411105 China Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China Department of Astronomy School of Physics and Materials Science Guangzhou University Guangzhou510006 China Villa Elisa Buenos Aires Argentina

We present the spectroscopy of the neutron star low-mass X-ray binary 4U 1636-53 using six simultaneous XMM-Newton and Rossi X-ray Timing Explorer observations. We applied different self-consistent reflection models to explore the features when the disk is illuminated by either the corona or the neutron star surface. We found that the spectra could be well fitted by these two types of models, with the derived emissivity index below a typical value of 3. The relative low emissivity can be explained if the neutron star and the corona, working together as an extended illuminator, simultaneously illuminate and ionize the disk. Additionally, the derived ionization parameter in the lamppost geometry is larger than the theoretical prediction. This inconsistency likely suggests that the corona does not emit isotropically in a realistic context. Furthermore, we also found that there is a possible trend between the height of the corona and the normalization of the disk emission. This could be understood either as a variation in the reflected radiation pressure or in the context of a jet base. Finally, we found that the disk is less ionized if it is illuminated by the neutron star, indicating that the illuminating source has significant influence on the physical properties of the disk. © The Authors 2023.

关键词： Stars

The polarization-angle flip in GRB prompt emission

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arXiv 2024年

作者： Cheng, Kangfa Zhao, Xiaohong Mao, Jirong Chen, Zhifu School of Mathematics and Physics Guangxi Minzu University Nanning530006 China Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Science China Center for Astronomical Mega-Science Chinese Academy of Science 20A Datun Road Chaoyang District Beijing100012 China

Context. In recent years, some polarization measurements of gamma-ray bursts (GRBs) have been reported, and the polarization-angle (PA) rotation in the prompt emission phase has been found in several bursts. The physical mechanism of the PA evolution is still unclear. In this work, we studied the origin of the PA rotation in a toroidal magnetic field. Aims. We aim to provide an explanation for the PA rotation in GRBs and find the physical conditions that lead to the rotation by 90 degrees in the toroidal magnetic-field (MF) model. Moreover, we present some observable polarization properties in the MF model that can be tested in the future. Methods. We calculated the instantaneous polarization degree (PD) from a top-hat jet with different normalized viewing angles (q = θv/θj), jet opening angles (θj), and jet Lorentz factors (Γ) in three wavebands. When the PD changes between positive and negative values, it means that the PA flips by 90 degrees. On these grounds, we can summarize the range of parameters required for these PA flips. Considering these parameter conditions, we can further estimate the observed rate of the GRBs exhibiting such PA rotations. Results. We find that the PA rotation in the toroidal MF is primarily related to three critical factors: the viewing angle, the jet opening angle, and the jet Lorentz factor. Additionally, the PA can experience flips of 90 degrees twice. The conditions for the flips are q 0.5 (except for q 1) and yj = (Γθj)2 4. However, the two flips in the PA might not be concurrently observable due to the constraint of flux. Taking these conditions into account and assuming a random orientation between the jet axis and the line of sight (LOS), we obtain a theoretical upper limit (without any constraints) for the observed rate of GRBs in the X-ray or γ-ray band displaying the flips in PA as Rch 80%. We further constrain the observed rate as Rch ∼ 16% according to the maximal post-flip polarized flux level, where the observed rate of

关键词： Polarization

Measuring clock jumps using pulsar timing

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Science China(Physics,Mechanics & Astronomy) 2020年第1期63卷 112-117页

作者： ZhiXuan Li KeJia Lee Ricardo Nicolaos Caballero YongHua Xu LongFei Hao Min Wang JianCheng Wang Yunnan Observatories Chinese Academy of SciencesKunming 650216China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China

In this paper,we investigate the statistical signal-processing algorithm to measure the instant local clock jump from the timing data of multiple *** algorithm is based on the framework of Bayesian *** order to make the Bayesian algorithm applicable with limited computational resources,we dedicated our efforts to the analytic marginalization of irrelevant *** found that the widely used parameter for pulsar timing systematics,the"Efac"parameter,can be analytically *** reduces the Gaussian likelihood to a function very similar to the Student’s *** iterative method to solve the maximum likelihood estimator is also explained in the *** pulsar timing data from the Yunnan Kunming 40-m radio telescope,we demonstrate the application of the method,where 80-ns level precision for the clock jump can be *** a precision is comparable to that of current commercial time transferring service using *** expect that the current method could help developing the autonomous pulsar time scale.

关键词： pulsars time series analysis clocks and frequency standards

Effect of irradiation on the spin of millisecond pulsars

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arXiv 2023年

作者： Lan, Shun-Yi Meng, Xiang-Cun Yunnan Observatories Chinese Academy of Sciences Kunming650011 China University of the Chinese Academy of Sciences 19A Yuquan Road Shijingshan District Beijing100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China

A millisecond pulsar (MSP) is an old neutron star (NS) that has accreted material from its companion star, causing it to spin up, which is known as the recycling scenario. During the mass transfer phase, the system manifests itself as an X-ray binary. PSR J1402+13 is an MSP with a spin period of 5.89 ms and a spin period derivative of log Pspin = −16.32. These properties make it a notable object within the pulsar population, as MSPs typically exhibit low spin period derivatives. In this paper, we aim to explain how an MSP can posses high spin period derivative by binary evolution. By utilizing the stellar evolution code MESA, we examine the effects of irradiation on the companion star and the propeller effect on the NS during binary evolution. We demonstrate that irradiation can modify the spin period and mass of an MSP, resulting in a higher spin period derivative. These results suggest that the irradiation effect may serve as a key factor in explaining MSPs with high spin period derivatives. © 2023, CC BY.

关键词： Mass transfer

Constraints on Common Envelope Ejection from Double Helium White Dwarfs

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arXiv 2024年

作者： Zhang, Yangyang Li, Zhenwei Chen, Xuefei Han, Zhanwen Zhoukou Normal University East Wenchang Street Chuanhui District Zhoukou466001 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Science China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China University of the Chinese Academy of Science Yuquan Road 19 Shijingshan Block Beijing100049 China

Double helium white dwarfs (He WDs) are one type of gravitational wave source and are greatly important in the studies of binary interaction, particularly in the common envelope (CE) ejection physics. Most double He WDs with mass ratios of q ∼ 1 are formed through a particular channel. In this channel, one He WD is initially produced from a red giant (RG) with a degenerate core via stable Roche lobe overflow, and another He WD is formed from an RG with a degenerate core via CE ejection. They may have significant implications for the binary evolution processes yet have not received specific studies, especially for the CE phase. This paper adopts a semi-analytic method and a detailed stellar evolution simulation to model the formation of double He WDs. We find that most double He WDs show mass ratios being slightly greater than 1, and their orbital periods and mass ratios relation are broadly consistent with observations. There is also a relation between the mass ratios and the progenitors’ masses of the He WDs produced via CE ejection for double He WDs with determined WD masses. Based on this relation, the mass of the He WD progenitor can be inferred from the mass ratio. Then, the CE ejection efficiency can be constrained with the orbital period. In addition, we constrain the CE ejection efficiency for two double He WDs, J1005-2249 and WD0957-666. The results show that the CE ejection efficiencies increase with the WD progenitor masses. Copyright © 2024, The Authors. All rights reserved.

关键词： White dwarfs

A method of photometric data extraction for asteroids from time-domain surveys

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arXiv 2024年

作者： Xu, Xiaoyun Wang, Xiaobing Muinonen, Karri Penttilä, Antti Luo, Nanping Gu, Shenghong Sun, Leilei Xu, Fukun Liu, Yisi Xiang, Yue Cao, Dongtao Wang, Jianhua Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Department of Physics University of Helsinki P.O. box 64 FI-00014 Finland Deep Space Exploration Laboratory Beijing100043 China

The lightcurves of asteroids are essential for determining their physical characteristics, including shape, spin, size, and surface composition. However, most asteroids are missing some of these basic physical parameters due to lack of photometric data. Although a few telescopes or surveys are specially designed for photometric lightcurve observations of asteroids, many ground-based and space-based sky surveys for hunting new exoplanets, transient events, etc., should capture numerous small Solar System objects. This will benefit the physical studies of these objects. In order to extract data of these moving objects from time-domain photometric surveys, we have developed a new method using the model tree algorithm in the field of machine learning. A dedicated module is built to automatically identify moving objects in dataset, and extract their photometric and astrometric data. As the first application of this novel method, we have analyzed data in five fields of the Yunnan-Hong Kong wide field photometric (YNHK) survey, from which 538 lightcurves of 211 asteroids are successfully extracted. Meanwhile, we also tested the method based on the data from NASA’s Transiting Exoplanet Survey Satellite, and the result proves the reliability of our method. With derived lightcurves of 13 asteroids from the YNHK survey, we have determined their synodic spin periods, among which the periods of 4 asteroids are estimated for the first time. In future, we are going to apply this method to search for small objects in the outer part of the Solar System from the Chinese Space Station Telescope survey. Copyright © 2024, The Authors. All rights reserved.

关键词： NASA

Early phase simultaneous multi-band observations of Type II supernova SN 2024ggi with Mephisto

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arXiv 2024年

作者： Chen, Xinlei Kumar, Brajesh Er, Xinzhong Guo, Helong Yang, Yuan-Pei Lin, Weikang Fang, Yuan Du, Guowang Liu, Chenxu Zhao, Jiewei Zhang, Tianyu Bao, Yuxi Zou, Xingzhu Pan, Yu Wang, Yu Zhu, Xufeng Chatterjee, Kaushik Liu, Xiangkun Liu, Dezi Lagioia, Edoardo P. Rangwal, Geeta Zhong, Shiyan Zhang, Jinghua Lian, Jianhui Cai, Yongzhi Zhang, Yangwei Liu, Xiaowei South-Western Institute for Astronomy Research Yunnan University Yunnan Kunming650504 China Department of Astronomy Yunnan University Yunnan Kunming650504 China Yunnan Observatories Chinese Academy of Sciences Yunnan Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Yunnan Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Yunnan Kunming650216 China

We present early-phase good cadence simultaneous multi-band (ugi, urz–bands) imaging of nearby supernova SN 2024ggi, which exploded in the nearby galaxy, NGC 3621. A quick follow-up was conducted within less than a day after the explosion and continued ∼23 days. The uvg-band light curves display a rapid rise (∼1.4 mag day−1) to maximum in ∼4 days and absolute magnitude mg ∼–17.75 mag. The post-peak decay rate in redder bands is ∼0.01 mag day−1. Different colors (e.g., u − g and v− r) of SN 2024ggi are slightly redder than SN 2023ixf. A significant rise (∼12.5 kK) in black-body temperature (optical) was noticed within ∼2 days after the explosion, which successively decreased, indicating shock break out inside a dense circumstellar medium (CSM) surrounding the progenitor. Using semi-analytical modeling, the ejecta mass and progenitor radius were estimated as 1.2 M☉ and ∼550 R☉, respectively. The archival deep images (g, r, i, z-bands) from the Dark Energy Camera Legacy Survey (DECaLS) were examined, and a possible progenitor was detected in each band (∼22–22.5 mag) and had a mass range of 14–17 M☉. Copyright © 2024, The Authors. All rights reserved.

关键词： Supernovae

Photometric Study and Period Investigation of Two Contact Binaries: Vw Boo And V1128 Tau

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SSRN

SSRN 2023年

作者： Han, Quan-Wang Jiang, Deng-Kai School of Physics and Electronics Qiannan Normal University for Nationalities Duyun558000 China Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China

We analyzed the TESS data of VW Boo and V1128 Tau by using the Wilson-Devinney code. The obtained solutions reveal that these two systems are shallow-contact binaries. The fill-out factors for VW Boo and V1128 Tau are 10.35% and 17.20%, respectively. Period investigations were conducted based on all available times of minimum. Our results show that the orbital period of VW Boo is decreasing at a rate of dP/dt = −1.52 × 10−7 days yr−1, together with a cyclic oscillation having a period of 27.179 yr and a semi-amplitude of 0.0063 d. Similarly, the orbital period of V1128 Tau also shows a secular decrease (dP/dt = −1.40 × 10−7 days yr−1), along with a cyclic oscillation (P3= 16.125 yr and K3 = 0.0011). The secular decrease might be caused by mass transfer, while the cyclic oscillation might be caused by the presence of a third body or magnetic activity. © 2023, The Authors. All rights reserved.

关键词： Mass transfer