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Interacting system NGC 7805/6(Arp 112)and its tidal dwarf galaxy candidate

research in Astronomy and astrophysics 2021年第2期21卷 149-156页

作者： Zhen-Xing Fu Chandreyee Sengupta Ramya Sethuram Bikram Pradhan Mridweeka Singh Kuntal Misra TomCScott Yin-Zhe Ma Purple Mountain Observatory(CAS) Nanjing 210034China School of Astronomy and space Sciences University of Science and Technology of ChinaHefei 230026China Indian institute of astrophysics KoramangalaBangalore 560034India Aryabhatta research institute of Observational Sciences Manora PeakNainital 263001India Korea Astronomy and space Science institute 776 Daedeokdae-roYuseong-guDaejeon 34055Republic of Korea institute of astrophysics and space Sciences(IA) Rua das Estrelas4150-762 PortoPortugal School of Chemistry and Physics University of KwaZulu-NatalWestville CampusPrivate Bag X54001Durban4000South Africa NAOC-UKZN Computational astrophysics Centre(NUCAC) University of KwaZulu-NatalDurban4000South Africa

We present results from our Giant Metrewave Radio Telescope(GMRT)HⅠ,Himalayan Chandra Telescope(HCT)Hα,1 m Sampurnanand Telescope(ST)and 1.3 m Devasthal Fast Optical Telescope(DFOT)deep optical observations of the NGC 7805/6(Arp 112)system to test KUG 2359+311’s tidal dwarf galaxy(TDG)candidacy and explore the properties of the interacting *** GMRT HⅠmap shows no HⅠdetection associated with KUG 2359+311,nor any HⅠtail or bridge-like structure connecting KUG 2359+311 to the NGC 7805/6 *** HCT Hαimage,on the other hand,displays strong detections in KUG 2359+311,with net SFR0.035±0.009 M_(⊙)yr^(-1).The Hαdata constrain the redshift of KUG 2359+311 to 0.00≤z≤0.043,compared to the redshift of NGC 7806 *** detected to date have all been HⅠrich,and displayed HⅠ,ionised gas and stellar tidal debris trails(bridges or tails)linking them to their parent ***,neither our HⅠdata nor our optical imaging,while three magnitudes deeper than SDSS,reveals a tidal trail connecting KUG 2359+311 to NGC 7805/*** of HⅠ,presence of an old stellar population,ongoing star formation and reasonably high SFR compared to normal dwarf galaxies suggest that KUG 2359+311 may not be an Arp 112 *** is most likely a case of a regular gas-rich dwarf galaxy undergoing a morphological transformation after having lost its entire gas content to an interaction with the Arp 112 *** and metallicity from future spectroscopic observations of KUG 2359+311 would help clarify the nature of this enigmatic structure.

关键词： galaxies dwarf-galaxies interactions-galaxies spiral-galaxies star formation-galaxies peculiar-radio lines galaxies

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Forecast of cosmological constraints with type Ia supernovae from the Chinese space Station Telescope

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Science China(Physics,Mechanics & Astronomy) 2023年第2期66卷 131-139页

作者： Shi-Yu Li Yun-Long Li Tianmeng Zhang Jozsef Vink Eniko Regos Xiaofeng Wang Gaobo Xi Hu Zhan Beijing Planetarium Beijing Academyof Scienceand TechnologyBeijing 100044China National space Science Center Chinese Academyof SciencesBeijing 100190China National space ScienceData Centerof China Beijing 101407China Key Laboratory of space Astronomy and technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 1oo10lChina School of Astronomy and space Science University of Chinese Academy of SciencesBeijing 101408China Konkoly Observatory Konkoly Institute of AstronomyKonkoly Thege M.ut 15-17Budapest 1121Hungary ELTE Eotvos Lorand University Institute of PhysicsPazmany Peter setany I/ABudapest 1117Hungary institute of Physics Universityof SzegedDom ter9Szeged 6720Hungary Physics Department and Tsinghua Center for astrophysics(THCA) Tsinghua UniversityBeijing 100084China kavli institute forAstronomy and astrophysics Peking UniversityBeijingio0871China

The 2-m aperture Chinese space Station Telescope(CSST),which observes at wavelengths ranging from 255 to 1000 nm,is expected to start science operations in *** ultra-deep field observation program covering approximately 10 deg2is proposed with supernovae(SNe) and other transients as one of its primary science *** paper presents the simulated detection results of type Ⅰa supernovae(SNe Ⅰa) and explores the impact of new datasets on the determinations of cosmological *** simulated observations are conducted with an exposure time of 150 s and cadences of 10,20,and 30 *** survey mode covering a total of 80 observations but with a random cadence in the range of 4 to 14 d is also *** simulation results indicate that the CSST can detect up to ~1800 SNe la at z <*** simulated SNe la are then used to constrain the cosmological *** constraint on can be improved by 37.5% using the 10-d cadence sample in comparison with the Pantheon sample.A deeper measurement simulation with a 300 s exposure time together with the Pantheon sample improves the current constraints on Ωmby 58.3% and ω by 47.7%.Taking future lager sets of nearby SN Ⅰa sample form ground-based surveys(i.e.,N~3400) into consideration,the constraints on ω can be improved by 59.1%.The CSST ultra-deep field observation program is expected to discover large amounts of SNe la over a broad redshift span and enhance our understanding of the nature of dark energy.

关键词： supernovae survey Station

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On the knee of Galactic cosmic rays in light of sub-TeV spectral hardenings

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Chinese Physics C 2018年第7期42卷 113-122页

作者： Yi-Qing Guo1 2 Qiang Yuan1 3 1. Key Laboratory of Dark Matter and space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China 2. Key Laboratory of Particle astrophysics institute of High Energy Physics Key Laboratory of Dark Matter and space Astronomy Purple Mountain ObservatoryChinese Academy of Sciences Key Laboratory of Particle astrophysics Institute of High Energy PhysicsChinese Academy of Sciences School of Astronomy and space Science University of Science and Technology of China

More than fifty years after the discovery of the knee in the cosmic ray （CR） spectra, its physical origin remains a mystery. This is partly due to the ambiguity of the energy spectra of individual components. Recently, direct measurements from several space experiments found significant spectral hardenings of CR nuclei at ~200 GV. A joint modeling of the direct and indirect measurements may help to understand the experimental systematics and the physics of the knee. In this work, we update the phenomenological ＂poly-gonato＂ model to include the spectral hardenings, with a changing spectral index of γ ＋ β·logE. This modification gives a reasonable description of the CR spectra in a wide energy range. However, the fits to different data sets give different results. We find that the fit to the AMS-02 and CREAM data slightly favors a relatively low energy knee of the light components. In such a case, the expected all-particle spectra under-shoot the data, which may require an extra component of CRs. The fits to AMS-02 data and the light component （H＋He） data from the Tibet ASγ/ARGO-YBJ/WFCTA and KASCADE experiments give consistent results with the all-particle spectra. We further propose a possible physical realization of such a ＂modified poly-gonato＂ model of spectral hardenings by means of spatially-dependent diffusion of CRs. We find reasonably good agreement between the model predictions and the data for CR spectra, the secondary-to-primary ratios, and the amplitude of anisotropies.

关键词： cosmic ray knee spectrum propagation

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Automated lfare forecasting using a statistical learning technique

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research in Astronomy and astrophysics 2010年第8期10卷 785-796页

作者： Yuan Yuan Frank Y. Shih Ju Jing Hai-Min Wang Computer Vision Laboratory Department of Computer Science New Jersey Institute of Technology Newark NJ 07102 USA space Weather research Laboratory Physics Department New Jersey Institute of Technology Newark NJ 07102 USA

We present a new method for automatically forecasting the occurrence of solar flares based on photospheric magnetic measurements. The method is a cascading combination of an ordinal logistic regression model and a support vector machine classifier. The predictive variables are three photospheric magnetic parameters, i.e., the total unsigned magnetic flux, length of the strong-gradient magnetic polarity inversion line, and total magnetic energy dissipation. The output is true or false for the occurrence of a certain level of flares within 24 hours. Experimental results, from a sample of 230 active regions between 1996 and 2005, show the accuracies of a 24- hour flare forecast to be 0.86, 0.72, 0.65 and 0.84 respectively for the four different levels. Comparison shows an improvement in the accuracy of X-class flare forecasting.

关键词： Sun flares -- Sun magnetic fields

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A new segmentation algorithm for lunar surface terrain based on CCD images

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research in Astronomy and astrophysics 2015年第9期15卷 1604-1612页

作者： Hong-Kun Jiang Xiao-Lin Tian Ao-Ao Xu Lunar and Planetary Science Laboratory/space Science institute Macao University of Science and Technology

Terrain classification is one of the critical steps used in lunar geomorphologic analysis and landing site selection. Most of the published works have focused on a Digital Elevation Model （DEM） to distinguish different regions of lunar terrain. This paper presents an algorithm that can be applied to lunar CCD images by blocking and clustering according to image features, which can accurately distinguish between lunar highland and lunar mare. The new algorithm, compared with the traditional algo- rithm, can improve classification accuracy. The new algorithm incorporates two new features and one Tamura texture feature. The new features are generating an enhanced image histogram and modeling the properties of light reflection, which can represent the geological characteristics based on CCD gray level images. These features are ap- plied to identify texture in order to perform image clustering and segmentation by a weighted Euclidean distance to distinguish between lunar mare and lunar highlands. The new algorithm has been tested on Chang＇e-1 CCD data and the testing result has been compared with geological data published by the U.S. Geological Survey. The result has shown that the algorithm can effectively distinguish the lunar mare from highlands in CCD images. The overall accuracy of the proposed algorithm is satisfactory, and the Kappa coefficient is 0.802, which is higher than the result of combining the DEM with CCD images.

关键词： Moon -- methods: data analysis -- techniques: image processing

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Machine Learning for Improving Stellar Image-based Alignment in Wide-field Telescopes

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research in Astronomy and astrophysics 2022年第1期22卷 85-95页

作者： Zhixu Wu Yiming Zhang Rongxin Tang Zhengyang Li Xiangyan Yuan Yong Xia Hua Bai Bo Li Zhou Chen Xiangqun Cui Xiaohua Deng institute of space Science and technology Nanchang UniversityNanchang 330031China Nanjing institute of Astronomical Optics and technology Chinese Academy of SciencesNanjing 210042China

Stellar images will deteriorate dramatically when the sensitive elements of wide-field survey telescopes are misaligned during an observation, and active alignment is the key technology to maintain the high resolution of wide-field sky survey telescopes. Instead of traditional active alignment based on field-dependent wave front errors, this work proposes a machine learning alignment metrology based on stellar images of the scientific camera,which is more convenient and higher speed. We first theoretically confirm that the pattern of the point-spread function over the field is closely related to the misalignment status, and then the relationships are learned by twostep neural networks. After two-step active alignment, the position errors of misalignment parameters are less than5 μm for decenter and less than 5″ for tip-tilt in more than 90% of the cases. The precise alignment results indicate that this metrology provides a low-cost and high-speed solution to maintain the image quality of wide-field sky survey telescopes during observation, thus implying important significance and broad application prospects.

关键词： telescopes techniques:high angular resolution techniques:miscellneous

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Discovery of Balmer broad absorption lines in the quasar LBQS 1206+1052

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research in Astronomy and astrophysics 2012年第4期12卷 369-382页

作者： Tuo Ji Ting-Gui Wang Hong-Yan Zhou Hui-Yuan Wang Key Laboratory for research in Galaxies and Cosmology University of Science and Technology of China （USTC） Hefei 230026 China Center for astrophysics USTC Hefei 230026 China Polar research institute of China Shanghai 200136 China

We report the discovery of Balmer broad absorption lines （BALs） in the quasar LBQS 1206＋1052 and present a detailed analysis of the peculiar absorption line spectrum. Besides the Mg II λλ2796, 2803 doublet, BALs are also detected in the He I＊ multiplet at λλ2946, 3189, 3889 A arising from the metastable helium 2 3 S level, and in Hα and Hβ from the excited hydrogen H I＊ n = 2 level, which are rarely seen in quasar spectra. We identify two components in the BAL troughs of v ～ 2000 km s 1 width： One component shows an identical profile in H I＊, He I＊ and Mg II with its centroid blueshifted by v c ≈ 726 km s-1 . The other component is detected in He I＊ and Mg II with v c ≈ 1412 km s-1 . We estimate the column densities of H I＊, He I＊, and Mg II, and compare them with possible level population mechanisms. Our results favor the scenario that the Balmer BALs originate in a partially ionized region with a column density of N H ～ 10 21 10 22 cm-2 for an electron density of n e ～ 10 6 10 8 cm-3 via Lyα resonant scattering pumping. The harsh conditions needed may help to explain the rarity of Balmer absorption line systems in quasar spectra. With an i-band PSF magnitude of 16.50, LBQS 1206＋1052 is the brightest Balmer-BAL quasar ever reported. Its high brightness and unique spectral properties make LBQS 1206＋1052 a promising candidate for followup high-resolution spectroscopy, multi-band observations, and long-term monitoring.

关键词： galaxies active -- quasar absorption lines -- quasar individual (LBQS1206+1052)

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Mapping and compositional analysis of mare basalts in the Aristarchus region of the Moon using Clementine data

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research in Astronomy and astrophysics 2014年第1期14卷 113-128页

作者： Feng Zhang Yong-Liao Zou Yong-Chun Zheng Xiao-Hui Fu Yong-Chao Zhu National Astronomical Observatories Chinese Academy of Sciences University of Chinese Academy of Sciences space Science institute Macao University of Science and Technology Center for space Science research and Department of Mathematics The Hong Kong University of Science and Technology

The process of accurately defining and outlining mare basalt units is nec- essary for constraining the stratigraphy and ages of basalt units, which are used to determine the duration and the flux of lunar volcanism. We use a combination of Clementine＇s five-band ultraviolet/visible data and Ti02 and FeO abundance distri- bution maps to define homogenous mare basalt units and characterize their composi- tional variations （with maturity） in the Aristarchus region. With 20 groups of distinct mare basaltic soils identified using the method in this paper, six additional spectrally defined areas and five basaltic units are constructed, and their mineralogic quanfiza- tion values provide new constraints on their temporal and spatial evolution. Our results indicate that the Aristarchus region has diverse basalt units and a complex history of volcanic evolution. We also demonstrate that the techniques, from which spectrally distinct mare basalts can be mapped, performed well in this study and can be confi- dently expanded to other mare regions of the Moon.

关键词： spectroscopic -- image processing -- data analysis -- Moon

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A Lattice Non-Perturbative Definition of an SO(10) Chiral Gauge Theory and Its Induced Standard Model

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Chinese Physics Letters 2013年第11期30卷 54-58页

作者： WEN Xiao-Gang Perimeter institute for Theoretical Physics WaterlooOntario N2L 2Y5Canada Department of Physics Massachusetts Institute of TechnologyCambridgeMassachusetts 02139USA

The standard model is a chiral gauge theory where the gauge fields couple to the right-hand and the left-hand fermions *** standard model is defined perturbatively and describes all elementary particles(except gravitons)very ***,for a long time,we do not know if we can have a non-perturbative definition of the standard model as a Hamiltonian quantum mechanical *** we propose a way to give a modified standard model(with 48 two-component Weyl fermions)a non-perturbative definition by embedding the modified standard model into an SO(10)chiral gauge *** show that the SO(10)chiral gauge theory can be put on a lattice(a 3D spatial lattice with a continuous time)if we allow fermions to *** a non-perturbatively defined standard model is a Hamiltonian quantum theory with a finite-dimensional Hilbert space for a finite space *** generally,using the defining connection between gauge anomalies and the symmetry-protected topological orders,one can show that any truly anomaly-free chiral gauge theory can be non-perturbatively defined by putting it on a lattice in the same dimension.

关键词： theory gauge chiral

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The Energy Sources of Superluminous Supernovae

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research in Astronomy and astrophysics 2019年第5期19卷 1-14页

作者： Shan-Qin Wang Ling-Jun Wang Zi-Gao Dai School of Astronomy and space Science Nanjing University Guangxi Key Laboratory for Relativistic astrophysics School of Physical Science and Technology Guangxi University Key Laboratory of Modern Astronomy and astrophysics (Nanjing University) Ministry of Education Astroparticle Physics Institute of High Energy Physics Chinese Academy of Sciences

Supernovae(SNe) are the most brilliant optical stellar-class explosions. Over the past two decades, several optical transient survey projects discovered more than-100 so-called superluminous supernovae(SLSNe) whose peak luminosities and radiated energy are ■ 7 × 10^(43) erg s^(-1) and > 10^(51) erg respectively, at least an order of magnitude larger than those of normal SNe. According to their optical spectra features, SLSNe have been split into two broad categories of type Ⅰ that are hydrogen-deficient and type Ⅱ that are hydrogen-rich. Investigating and determining the energy sources of SLSNe would be of outstanding importance for understanding their stellar evolution and explosion mechanisms. The energy sources of SLSNe can be determined by analyzing their light curves(LCs) and spectra. The most prevailing models accounting for the SLSN LCs are the ^(56)Ni cascade decay model, the magnetar spin-down model,the ejecta-circumstellar medium interaction model and the jet-ejecta interaction model. In this review, we present several energy-source models and their different combinations.

关键词： stars magnetars-supernovae general

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