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Morpho-Photometric Classification of KiDS DR5 Sources Based on Neural Networks: A Comprehensive Star-Quasar-Galaxy Catalog

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arXiv 2024年

作者： Feng, Hai-Cheng Li, Rui Napolitano, Nicola R. Li, Sha-Sha Bai, J.M. Dong, Yue Li, Ran Liu, H.T. Lu, Kai-Xing Pan, Zhi-Wei Radovich, Mario Shan, Huan-Yuan Wang, Jian-Guo Xi, Wen-Zhe Xie, Ling-Hua Yuan, Zun-Li Zhang, Yang-Wei 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 Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory of Radio Astronomy and Technology Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100101 China Institude for Astrophysics School of Physics Zhengzhou University Zhengzhou450001 China School of Physics and Astronomy Sun Yat-sen University Zhuhai Campus 2 Daxue Road Xiangzhou District Zhuhai China CSST Science Center for Guangdong-Hong Kong-Macau Great Bay Area Zhuhai519082 China INAF Osservatorio Astronomico di Capodimonte Salita Moiariello 16 Napoli80131 Italy School of Mathematics and Physics Xi’an Jiaotong-Liverpool University 111 Renai Road Suzhou215123 China University of Chinese Academy of Sciences Beijing100049 China National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Department of Astronomy School of Physics Peking University Beijing100871 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China INAF Osservatorio Astronomico di Padova via dell’Osservatorio 5 Padova35122 Italy Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai200030 China Department of Physics School of Physics and Electronics Hunan Normal University Changsha410081 China South-Western Institute for Astronomy Research Yunnan University Kunming650500 China

We present a novel multimodal neural network (MNN) for classifying astronomical sources in multiband ground-based observations, from optical to near infrared, to separate sources in stars, galaxies and quasars. Our approach combines a convolutional neural network branch for learning morphological features from r-band images with an artificial neural network branch for extracting spectral energy distribution (SED) information. Specifically, we have used 9-band optical (ugri) and NIR (ZY HJKs) data from the Kilo-Degree Survey (KiDS) Data Release 5. The two branches of the network are concatenated and feed into fully-connected layers for final classification. We train the network on a spectroscopically confirmed sample from the Sloan Digital Sky Survey cross-matched with KiDS. The trained model achieves 98.76% overall accuracy on an independent testing dataset, with F1 scores exceeding 95% for each class. Raising the output probability threshold, we obtain higher purity at the cost of a lower completeness. We have also validated the network using external catalogs cross-matched with KiDS, correctly classifying 99.74% of a pure star sample selected from Gaia parallaxes and proper motions, and 99.74% of an external galaxy sample from the Galaxy and Mass Assembly survey, adjusted for low-redshift contamination. We apply the trained network to 27,335,836 KiDS DR5 sources with r ≤ 23 mag to generate a new classification catalog. This MNN successfully leverages both morphological and SED information to enable efficient and robust classification of stars, quasars, and galaxies in large photometric surveys. © 2024, CC BY.

关键词： Infrared devices

The black hole spin in coalescing binary black holes and high-mass X-ray binaries

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Proceedings of the International Astronomical Union 2019年第S346期14卷 426-432页

作者： Qin, Y. Fragos, T. Meynet, G. Marchant, P. Kalogera, V. Andrews, J. Sørensen, M. Song, H.F. Geneva Observatory University of Geneva Switzerland Center for Interdisciplinary Exploration and Research in Astrophysics Department of Physics and Astrophysics Northwestern University Evanston 60208 IL United States Foundation for Research and Technology-Hellas IESL Voutes Heraklion 71110 Greece Physics Department Institute of Theoretical and Computational Physics University of Crete Heraklion Crete 71003 Greece College of Physics Guizhou University Guiyang City Guizhou Province 550025 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China

The six LIGO detections of merging black holes (BHs) allowed to infer slow spin values for the two pre-merging BHs. The three cases where the spins of the BHs can be determined in high-mass X-ray binaries (HMXBs) show that those BHs have high spin values. We discuss here scenarios explaining these differences in spin properties in these two classes of object. © International Astronomical Union 2019.

关键词： Binaries: Close binary stars black hole gravitational waves X-rays: Binaries

The force-free dipole magnetosphere in non-linear electrodynamics

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arXiv 2019年

作者： Li, Huiquan Yang, Xiaolin Wang, Jiancheng Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China

Quantum electrodynamics (QED) effects may be included in physical processes of magnetar and pulsar magnetospheres with strong magnetic fields. Involving the quantum corrections, the Maxwell electrodynamics is modified to non-linear electrodynamics. In this work, we study the force-free magnetosphere in non-linear electrodynamics in a general framework. The pulsar equation describing a steady and axisymmetric magnetosphere is derived, which now admits solutions with corrections. We derive the first-order non-linear corrections to the near-zone dipole magnetosphere in some popular non-linear effective theories. The field lines of the corrected dipole tend to converge on the rotational axis so that the fields in the polar region are stronger compared to the pure dipole case. Copyright © 2019, The Authors. All rights reserved.

关键词： Electrodynamics

A flexible method for estimating luminosity functions via Kernel Density Estimation

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arXiv 2020年

作者： Yuan, Zunli Jarvis, Matt J. Wang, Jiancheng Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China Astrophysics University of Oxford Denys Wilkinson Building Keble Road OxfordOX1 3RH United Kingdom Physics and Astronomy Department University of the Western Cape Bellville7535 South Africa

We propose a flexible method for estimating luminosity functions (LFs) based on kernel density estimation (KDE), the most popular nonparametric density estimation approach developed in modern statistics, to overcome issues surrounding binning of LFs. One challenge in applying KDE to LFs is how to treat the boundary bias problem, since astronomical surveys usually obtain truncated samples predominantly due to the flux-density limits of surveys. We use two solutions, the transformation KDE method (t), and the transformation-reflection KDE method (tr) to reduce the boundary bias. We develop a new likelihood cross-validation criterion for selecting optimal bandwidths, based on which, the posterior probability distribution of bandwidth and transformation parameters for t and tr are derived within a Markov chain Monte Carlo (MCMC) sampling procedure. The simulation result shows that t and tr perform better than the traditional binned method, especially in the sparse data regime around the flux-limit of a survey or at the bright-end of the LF. To further improve the performance of our KDE methods, we develop the transformation-reflection adaptive KDE approach (tra). Monte Carlo simulations suggest that it has a good stability and reliability in performance, and is around an order of magnitude more accurate than using the binned method. By applying our adaptive KDE method to a quasar sample, we find that it achieves estimates comparable to the rigorous determination in a previous work, while making far fewer assumptions about the LF. The KDE method we develop has the advantages of both parametric and non-parametric methods. Copyright © 2020, The Authors. All rights reserved.

关键词： Surveys

SCATTER: A New Common Envelope Formalism

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arXiv 2022年

作者： Di Stefano, Rosanne Kruckow, Matthias U. Gao, Yan Neunteufel, Patrick G. Kobayashi, Chiaki Harvard-Smithsonian Center for Astrophysics 60 Garden St CambridgeMA02138 United States Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Département d’Astronomie Université de Genève Chemin Pegasi 51 VersoixCH-1290 Switzerland Université de Genève GenevaCH-1211 Switzerland University of Chinese Academy of Sciences China Institute of Gravitational Wave Astronomy School of Physics and Astronomy University of Birmingham BirminghamB15 2TT United Kingdom Max Planck Institut für Astrophysik Karl-Schwarzschild-Straße 1 Garching bei München85748 Germany Centre for Astrophysics Research Department of Physics Astronomy and Mathematics University of Hertfordshire HatfieldAL10 9AB United Kingdom

One of the most mysterious astrophysical states is the common envelope (CE) phase of binary evolution, in which two stars are enshrouded by the envelope shed by one of them. Interactions between the stars and the envelope shrinks the orbit. The CE can lead to mergers or to a subsequent phase of interactions. Mergers may involve any combination of two compact objects and/or stars. Some involving white dwarfs, may produce Type Ia supernovae, while merging neutron stars may yield gamma-ray bursts, and merging compact objects of all kinds produce gravitational radiation. Since CEs can arise from a variety of different initial conditions, and due to the complexity of the processes involved, it is difficult to predict their end states. When many systems are being considered, as in population synthesis calculations, conservation principles are generally employed. Here we use angular momentum in a new way to derive a simple expression for the final orbital separation. This method provides advantages for the study of binaries and is particularly well-suited to higher order multiples, now considered to be important in the genesis of potential mergers. Here we focus on CEs in binaries, and the follow-up paper extends our formalism to multiple star systems within which a CE occurs. © 2022, CC0.

关键词： Merging

Searching for quasi-periodic modulations in γ-ray active galactic nuclei

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arXiv 2020年

作者： Zhang, Peng-Fei Yan, Da-Hai Zhou, Jia-Neng Wang, Jian-Cheng Zhang, Li Department of Astronomy School of Physics and Astronomy Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing210008 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatory Chinese Academy of Sciences Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China

We perform a systematic search of quasi-periodic variabilities in γ-ray active galactic nuclei (AGNs) in the third Fermi Large Area Telescope source catalog (3FGL). We employe two techniques, Lomb-Scargle Periodogram (LSP) and Weighted Wavelet Z-transform (WWZ), to obtain power spectra of γ-ray light curves covering from 2008 August to 2016 December. The results show that besides several objects that have been reported in previous works, an additional source, the FSRQ PKS 0601-70 has a possible quasi-periodic variability of 450 days in its γ-ray light curves with the significance of > 3σ. The physical implications of our findings are discussed. Copyright © 2020, The Authors. All rights reserved.

关键词： Z transforms

First photometric study of ultrashort-period contact binary 1SWASP J140533.33＋114639.1

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Research in Astronomy and Astrophysics 2018年第3期18卷 57-62页

作者： Bin Zhang Sheng-Bang Qian Ri Michel Boonrucksar Soonthornthum Li-Ying Zhu Yunnan Observatories Chinese Academy of Sciences Kunming 650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China University of Chinese Academy of Sciences Beijing 100049 China Instituto de Astronomia UNAM Ensenada Mexico National Astronomical Research Institute of Thailand Chiang Mai 50200 Thailand

In this paper,CCD photometric light curves for the short-period eclipsing binary 1 SWASP J140533.33＋114639.1（hereafter J1405） in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney（W-D） code. It is discovered that J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9±0.5% and a mass ratio of q = 1.55±0.02. In order to explain the asymmetric light curves of the system,a cool starspot on the more massive component is employed. This shallow contact eclipsing binary may have been formed from a short-period detached system through orbital shrinkage due to angular momentum loss. Based on the（O-C） method,the variation of orbital period is studied using all the available times of minimum light. The（O-C） diagram reveals that the period is increasing continuously at a rate of d P/dt = ＋2.09×10^-7 d yr^-1,which can be explained by mass transfer from the less massive component to the more massive one.

关键词： stars binaries close - stars binaries eclipsing - stars individual （1SWASPJ140533.33＋114639.1）

KIC 10736223: An Algol-type eclipsing binary just undergone the rapid mass-transfer stage

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arXiv 2020年

作者： Chen, Xinghao Zhang, Xiaobin Li, Yan Chen, Hailiang Luo, Changqing Su, Jie Chen, Xuefei Han, Zhanwen Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China University of Chinese Academy of Sciences Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China

This paper reports the discovery of an Algol system KIC 10736223 that just past the rapid mass transfer stage. From the light curve and radial-velocity modelling we find KIC 10736223 to be a detached Algol system with the less-massive secondary nearly filling its Roche lobe. Based on the short-cadence Kepler data, we analyzed intrinsic oscillations of the pulsator and identified six secured independent δ Scuti-type pulsation modes (f1, f3, f9, f19, f42, and f48). We compute two grids of theoretical models to reproduce the δ Scuti freqiencies, and find fitting results of mass-accreting models meet well with those of single-star evolutionary models. The fundamental parameters of the primary star yielded with asteroseismology are M = 1.57+0.05/-0.09 M☉, Z = 0.009 ± 0.001, R = 1.484+0.016/-0.028 R☉, log g = 4.291+0.004/-0.009, Teff = 7748+230/-378 K, L = 7.136+1.014/-1.519 L☉. The asteroseismic parameters match well with the dynamical parameters derived from the binary model. Moreover, our asteroseismic results show that the pulsator is an almost unevolved star with an age between 9.46-11.65 Myr for single-star evolutionary models and 2.67-3.14 Myr for mass-accreting models. Thereofore, KIC 10736223 may be an Algol system that has just undergone the rapid mass-transfer process. Copyright © 2020, The Authors. All rights reserved.

关键词： Mass transfer

Orbital period correction and light curve modeling of the W-subtype shallow contact binary OW Leo

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arXiv 2020年

作者： Zhou, Xiao Qian, Shengbang P.O. Box 110 Kunming650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P. O. Box 110 Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang Dis-trict Beijing100012 China University of The Chinese Academy of Sciences Yuquan Road 19# Sijingshang Block Beijing100049 China

Orbital period and multi-color light curves' investigation of OW Leo are presented for the first time. The orbital period of OW Leo is corrected from P = 0.325545 days to P = 0.32554052 days in our work, and the observational data from the All-Sky Automated Survey for SuperNovae (ASAS-SN) are used to test the newly determined orbital period. Then, the phased light curves are calculated with the new period and the Wilson-Devinney program is applied to model the light curves, which reveal that OW Leo is a W-subtype shallow contact binary system (q = 3.05, f = 12.8 %). The absolute physical parameters of the two component stars are estimated to be M1 = 0.31(1)M☉, M2 = 0.95(3)M☉, R1 = 0.63(1)R☉, R2 = 1.04(1)R☉, L1 = 0.43(1)L☉ and L2 = 1.01(2)L☉. The evolutionary status show that the more massive star is less evolved than the less massive star. OW Leo has very low metal abundance, which means its formation and evolution are hardly influenced by any additional component. It is formed from an initially detached binary systems through nuclear evolution and angular momentum loss via magnetic braking, and have passed a very long time of main sequence evolution. Copyright © 2020, The Authors. All rights reserved.

关键词： Systems (metallurgical)