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Clumpy metal concentrations in elliptical galaxies NGC 4374 and NGC 4636

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research in Astronomy and Astrophysics 2010年第3期10卷 220-226页

作者： Hai-Guang Xu Jun-Hua Gu Li-Yi Gu Zhong-Li Zhang Yu Wang Tao An Department of Physics Shanghai Jiao Tong University Shanghai 200240 China Max-Planck institut fur astrophysik D-85740 Garching Germany Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China

We present a high spatial resolution study of metal distributions in the nearby, gas-rich elliptical galaxies NGC 4374 and NGC 4636 with the Chandra ACIS archive data. We define the hardness ratio HrfeL as the ratio of the emission in 0.65- 1.4 keV to that in 0.3-0.6 keV and 1.4-3.5 keV （after the magnesium and silicon lines are excluded）, and Hrcont as the ratio of the emission in 1.4-3.5keV to that in 0.3- 0.6 keV, so that the HrfeL and Hrcont maps can be used to trace the iron abundance and gas temperature distributions, respectively. By applying the a Trous wavelet algorithm to the obtained emission hardness ratio maps, we reveal that the HrfeL distributions are highly irregular, exhibiting strong spatial variations on 0.1-1 re scales, which do not follow the Hrcont distributions. Since the effect of temperature variation is small, we conclude that most of the high-HrfeL regions are very likely to possess higher abundances than the ambient gas. We also find that these high-HrfeL substructures are not associated with either the LMXB or globular cluster populations, thus their origins should be related to AGN activity or mergers.

关键词： galaxies： elliptical and lenticular cD -- galaxies： individual （NGC 4374 NGC 4636） -- galaxies： ISM -- ISM： abundances -- X-rays： galaxies

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卫星星系的数目与中央星系性质关系的研究

天文学报 2022年第4期63卷 71-84页

作者：古慧王鹏徐迎中罗志全曲涵戴才萍西华师范大学物理与天文学院南充637002 中国科学院紫金山天文台南京210023 Leibniz-institut für astrophysik Potsdam Potsdam Germany D-14482 浙江大学物理学系杭州310058

卫星星系是研究星系形成的有力探针.近期的研究指出,中央星系是椭圆星系时,其卫星星系数目比旋涡星系多.为了探究这种差异,采用了新一代流体动力学模型(The Next Generation Illustris Simulations,简称TNG模拟)中TNG300-1的数据,选择... 详细信息

卫星星系是研究星系形成的有力探针.近期的研究指出,中央星系是椭圆星系时,其卫星星系数目比旋涡星系多.为了探究这种差异,采用了新一代流体动力学模型(The Next Generation Illustris Simulations,简称TNG模拟)中TNG300-1的数据,选择了恒星质量范围为10^(10)M⊙·h^(-1)≤Mc≤10^(12)M⊙·h^(-1)的中央星系,同时根据星系的核球质量与星系的恒星质量的比值(B/T)将这个范围的中央星系划分为旋涡星系和椭圆星系.使用统计学的方法进行分析后发现:当控制暗晕质量分布,使得不同形态的中央星系所处的暗晕的质量分布完全相同时,卫星星系分布存在新的差异,即旋涡星系的卫星星系数目更多.这一结论和观测结果相反,产生这一差异的主要原因是:旋涡星系的卫星星系包含更多的冷气体,使得旋涡星系的卫星星系恒星形成效率更高.

关键词：星系:矮星系丰度暗晕

A diagnostic of the orbital spectrum of LS 5039 with fermi-LAT

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research in Astronomy and Astrophysics 2019年第12期19卷 281-286页

作者： Zhi Chang Shu Zhang Yu-Peng Chen Long Ji Ling-Da Kong Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBejjing 100049China University of Chinese Academy of Sciences Beijing 100049China institut fur astronomie und astrophysik Kepler Center for Astro and Particle PhysicsEberhard Karls UniversitatSand 172076 TibingenGermany

LS 5039 is a well-known γ-ray binary system which consists of an unknown compact object and a massive companion O star. It shows rather stable emissions at high energies over years and hence serves as an ideal laboratory to investigate the emission mechanism for such peculiar systems which emit prominent γ-rays. To this end, we take the orbital phase resolved energy spectrum as observed by fermi-LAT over 10 years. We divide the orbit into four orbital phases, each with an orbital phase range of 0.25,centered at 0.00, 0.25, 0.50 and 0.75 respectively, where the phase 0.0 is the periastron and phase 0.5 is the apastron. The phases around 0.25 and 0.75 are symmetric and hence are supposed to have identical local acceleration environment. The spectral analysis shows that the fermi-LAT spectra are largely different from these two symmetric orbital phases: the emission from orbital phase 0.25 turns out to be significantly stronger than that from 0.75. This result does not fit a scenario that γ-rays are Doppler boosted emission from bow shock tails if LS 5039 has a shock configuration similar to PSr B1259-63, and indicates that the inverse Compton scatterings between the shock accelerated plasma and the stellar particle environment is the underline procedure. We also find that the previous report for a disappearance of the orbital modulation at 3–20 GeV is due to the similar spectral turn-over energies of the different orbital phases. The spectral properties of periastron and apastron regions are addressed in the context of the measurements in phase regions around 0.25 and 0.75.

关键词： binaries:general gamma rays:general

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一种新型超导母体:褶皱的蜂窝状空位有序

Science Bulletin 2021年第4期66卷 327-331,M0003页

作者：齐彦鹏应天平吴贤新董卓雅 Masato Sasase 张青刘为燕 Masaki Ichihara 马延航胡江平 Hideo Hosono School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China Materials research Center for Element Strategy Tokyo Institute o f TechnologyYokohama 226-8503Japan institut fur Theoretische Physik und astrophysik Julius-Maximilians-Universitat WurzburgWurzburg 97074Germany Beijing National Laboratory for Condensed Matter Physics and institute of Physics Chinese Academy of Sciences.Beijing 100190China

空位在材料体系中无处不在,空位的存在也极大地影响了材料的光学、热学、电学等性质.目前,空位的研究主要集中在弱关联的体系,而在强关联体系中的空位以及空位和其他新奇量子现象的关系则知之甚少.本文在强关联铱化物Ir16Sb18中发现了... 详细信息

空位在材料体系中无处不在,空位的存在也极大地影响了材料的光学、热学、电学等性质.目前,空位的研究主要集中在弱关联的体系,而在强关联体系中的空位以及空位和其他新奇量子现象的关系则知之甚少.本文在强关联铱化物Ir16Sb18中发现了一种新奇的空位有序:褶皱的蜂窝状空位序.理论计算表明实空间的空位有序来源于倒空间的费米面嵌套,而空位有序的形成破坏了对称性,使得费米面附近的电子局域化.通过在空位中引入Ir或者用rh来替代Ir,可以有效地破坏空位有序从而引入超导电性.空位有序与超导电性的竞争关系表明:具有褶皱的蜂窝状空位有序的Ir16Sb18是一种新型的超导母体.这种独特的褶皱蜂窝状空位有序,及其实空间-倒空间的关系,表明了"关联空位"的重要性,这为探索更多新奇量子临界现象带来契机.

关键词：量子现象蜂窝状超导电性费米面 16S 强关联弱关联褶皱

An investigation of flare emissions at multiple wavelengths

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research in Astronomy and Astrophysics 2021年第3期21卷 149-157页

作者：李东 Alexander Warmuth 卢磊宁宗军 Key Laboratory for Dark Matter and Space Science Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210033China CAS Key Laboratory of Solar Activity National Astronomical ObservatoriesBeijing 100101China State Key Laboratory of Space Weather Chinese Academy of SciencesBeijing 100190China Leibniz-institut für astrophysik Potsdam(AIP) An der Sternwarte 1614482 PotsdamGermany School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China

We report multi-wavelength observations of four solar flares on 2014 July 07.We firstly select these flares according to the soft X-ray(SXr)and extreme ultraviolet(EUV)emissions recorded by the Extreme Ultraviolet Variability Experiment and Geostationary Orbiting Environmental S atellites.Then their locations and geometries are identified from the full-disk images measured by the Atmospheric Imaging Assembly(AIA),and the time delays among the light curves in different channels are identified.The electron number densities are estimated using the differential emission measure method.We find that three of four flares show strong emissions in SXr channels and high temperature(>6 MK)EUV wavelengths during the impulsive phase,i.e.,AIA 131 A and 94 A,and then they emit peak radiation subsequently in the middle temperature(~0.6-3 MK)EUV channels.Moreover,they last for a long time and have smaller electron densities,which are probably driven by the interaction of hot diffuse flare loops.Only one flare emits radiation at almost the same time in all the observed wavelengths,lasts for a relatively short time,and has a larger electron density.It is also accompanied by a typeⅢradio burst.The bright emission at the EUV channel could be corresponding to the associated erupting filament.

关键词： Sun:flares Sun:radio radiation Sun:UV radiation Sun:X-rays,gamma rays

Numerical studies of the Kelvin-Hemholtz instability in a coronal jet

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research in Astronomy and Astrophysics 2018年第4期18卷 91-104页

作者： Tian-Le Zhao Lei Ni Jun Lin Udo Ziegler Yunnan Observatories Chinese Academy of Sciences Kunming 650216 China University of Chinese Academy of Sciences Beijing 100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing 100101 China Leibniz-institut fur astrophysik Potsdam Potsdam D-14482 Germany

Kelvin-Hemholtz（K-H）instability in a coronal EUV jet is studied via 2.5D MHD numerical simulations.The jet results from magnetic reconnection due to the interaction of the newly emerging magnetic field and the pre-existing magnetic field in the corona.Our results show that the Alfv e′n Mach number along the jet is about 5–14 just before the instability occurs,and it is even higher than 14 at some local areas.During the K-H instability process,several vortex-like plasma blobs with high temperature and high density appear along the jet,and magnetic fields have also been rolled up and the magnetic configuration including anti-parallel magnetic fields forms,which leads to magnetic reconnection at many X-points and current sheet fragments inside the vortex-like blob.After magnetic islands appear inside the main current sheet,the total kinetic energy of the reconnection outflows decreases,and cannot support the formation of the vortex-like blob along the jet any longer,then the K-H instability eventually disappears.We also present the results about how the guide field and flux emerging speed affect the K-H instability.We find that a strong guide field inhibits shock formation in the reconnecting upward outflow regions but helps secondary magnetic islands appear earlier in the main current sheet,and then apparently suppresses the K-H instability.As the speed of the emerging magnetic field decreases,the K-H instability appears later,the highest temperature inside the vortex blob gets lower and the vortex structure gets smaller.

关键词： Sun corona jet — Kelvin-Hemholtz instability — guide-field — method numerical simulations

Timing analysis of the black hole candidate EXO 1846–031 with Insight-HXMT monitoring

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research in Astronomy and Astrophysics 2021年第3期21卷 193-204页

作者： He-Xin Liu Yue Huang Guang-Cheng Xiao Qing-Cui Bu Jin-Lu Qu Shu Zhang Shuang-Nan Zhang Shu-Mei Jia fang-Jun Lu Xiang Ma Lian Tao Wei Zhang Li Chen Li-Ming Song Ti-Pei Li Yu-Peng Xu Xue-Lei Cao Yong Chen Cong-Zhan Liu Ce Cai Zhi Chang Gang Chen Tian-Xiang Chen Yi-Bao Chen Yu-Peng Chen Wei Cui Wei-Wei Cui Jing-Kang Deng Yong-Wei Dong Yuan-Yuan Du Min-Xue fu Guan-Hua Gao He Gao Min Gao Ming-Yu Ge Yu-Dong Gu Ju Guan Cheng-Cheng Guo Da-Wei Han Jia Huo Lu-Hua Jiang Wei-Chun Jiang Jing Jin Yong-Jie Jin Ling-Da Kong Bing Li Cheng-Kui Li Gang Li Mao-Shun Li Wei Li Xian Li Xiao-Bo Li Xu-fang Li Yang-Guo Li Zheng-Wei Li Xiao-Hua Liang Jing-Yuan Liao Bai-Sheng Liu Guo-Qing Liu Hong-Wei Liu Xiao-Jing Liu Yi-Nong Liu Bo Lu Xue-feng Lu Qi Luo Tao Luo Bin Meng Yi Nang Jian-Yin Nie Ge Ou Na Sai ren-Cheng Shang Xin-Ying Song Liang Sun Ying Tan You-Li Tuo Chen Wang Guo-feng Wang Juan Wang Ling-Jun Wang Weng-Shuai Wang Yu-Sa Wang Xiang-Yang Wen Bai-Yang Wu Bo-Bing Wu Mei Wu Shuo Xiao Shao-Lin Xiong He Xu Jia-Wei Yang Sheng Yang Yan-Ji Yang Yi-Jung Yang Qi-Bin Yi Qian-Qing Yin Yuan You Ai-Mei Zhang Cheng-Mo Zhang fan Zhang Hong-Mei Zhang Juan Zhang Tong Zhang Wan-Chang Zhang Wen-Zhao Zhang Yi Zhang Yi-fei Zhang Yong-Jie Zhang Yuan-Hang Zhang Yue Zhang Zhao Zhang Zhi Zhang Zi-Liang Zhang Hai-Sheng Zhao Xiao-fan Zhao Shi-Jie Zheng Yao-Guang Zheng Deng-Ke Zhou Jian-feng Zhou Yu-Xuan Zhu ren-Lin Zhuang Yue Zhu Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049China institut fur astronomie und astrophysik Kepler Center for Astro and Particle PhysicsEberhard Karls Universität72076 TubingenGermany Department of Astronomy Beijing Normal UniversityBeijing 100088China Department of Astronomy Tsinghua UniversityBeijing 100084China Department of Physics Tsinghua UniversityBeijing 100084China Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China College of Physics Sciences&Technology Hebei UniversityBaoding 071002Hebei ProvinceChina

We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICEr and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICEr(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GrS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.

关键词： X-ray binaries black hole candidate QPO EXO 1846–031

What causes the absence of pulsations in Central Compact Objects in supernova remnants?

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research in Astronomy and Astrophysics 2021年第11期21卷 243-254页

作者： Qi Wu Adriana MPires Axel Schwope Guang-Cheng Xiao Shu-Ping Yan Li Ji Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210033China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China Leibniz-institut fur astrophysik Potsdam(AIP) An der Sternwarte 1614482 PotsdamGermany

Most young neutron stars belonging to the class of Central Compact Objects(CCOs)in supernova remnants do not have known periodicities.We investigated seven such CCOs to understand the common reasons for the absence of detected pulsations.Making use of XMM-Newton,Chandra,and NICEr observations,we perform a systematic timing and spectral analysis to derive updated sensitivity limits for both periodic signals and multi-temperature spectral components that could be associated with radiation from hotspots on the neutron star surface.Based on these limits,we then investigated for each target the allowed viewing geometry that could explain the lack of pulsations.We find that it is unlikely(ribute that we do not see pulsations to an unfavorable viewing geometry for five considered sources.Alternatively,the carbon atmosphere model,which assumes homogeneous temperature distribution on the surface,describes the spectra equally well and provides a reasonable interpretation for the absence of detected periodicities within current limits.The unusual properties of CCOs with respect to other young neutron stars could suggest a different evolutionary path,as that proposed for sources experiencing episodes of significant fallback accretion after the supernova event.

关键词： methods:data analysis stars:neutron X-rays:stars

Dark energy in the Swampland Ⅱ

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Science China(Physics,Mechanics & Astronomy) 2019年第9期62卷 120-122页

作者： Lavinia Heisenberg Matthias Bartelmann robert Brandenberger Alexandre refregier institute for Theoretical Studies ETH ZurichClausiusstrasse 47Zurich 8092Switzerland Universitat Heidelberg Zentrum fur AstronomieInstitut fur Theoretische AstrophysikHeidelberg D-69120 Germany Physics Department McGill UniversityMontrealQCH3A 2 T8Canada institute for Astronomy Department of PhysicsETH ZurichWolfgang-Pauli-Strasse 27Zurich 8093Switzerland

We have recently pointed out [1] that the string swampland conjectures [2], if true, provide important constraints on dark energy models. The constraints apply to the field range of a scalar field Φ described by an e... 详细信息

关键词： Dark energy Swampland