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arXiv 2024年

作者： Zhang, Yan-Qiu Xiong, Shao-Lin Mao, Ji-Rong Zhang, Shuang-Nan Xue, Wang-Chen Zheng, Chao Liu, Jia-Cong Zhang, Zhen Wang, Xi-Lu Ge, Ming-Yu Yi, Shu-Xu Song, Li-Ming An, Zheng-Hua Cai, Ce Li, Xin-Qiao Peng, Wen-Xi Tan, Wen-Jun Wang, Chen-Wei Wen, Xiang-Yang Wang, Yue Xiao, Shuo Zhang, Fan Zhang, Peng Zheng, Shi-Jie Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China University of Chinese Academy of Sciences Beijing100049 China Yunnan Observatories Chinese Academy of Sciences Yunnan Province Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China College of Physics Hebei Key Laboratory of Photophysics Research and Application Hebei Normal University Hebei Shijiazhuang050024 China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal University Guiyang550001 China College of Electronic and Information Engineering Tongji University Shanghai201804 China

As the brightest gamma-ray burst ever observed, GRB 221009A provided a precious opportunity to explore spectral line features. In this paper, we performed a comprehensive spectroscopy analysis of GRB 221009A jointly with GECAM-C and Fermi/GBM data to search for emission and absorption lines. For the first time we investigated the line feature throughout this GRB including the most bright part where many instruments suffered problems, and identified prominent emission lines in multiple time intervals. The central energy of the Gaussian emission line evolves from about 37 MeV to 6 MeV, with a nearly constant ratio (about 10%) between the line width and central energy. Particularly, we find that both the central energy and the energy flux of the emission line evolve with time as a power law decay with power law index of -1 and -2 respectively. We suggest that the observed emission lines most likely origin from the blue-shifted electron positron pair annihilation 511 keV line. We find that a standard high latitude emission scenario cannot fully interpret the observation, thus we propose that the emission line comes from some dense clumps with electron positron pairs traveling together with the jet. In this scenario, we can use the emission line to directly, for the first time, measure the bulk Lorentz factor of the jet (Γ) and reveal its time evolution (i.e. Γ ∼ t−1) during the prompt emission. Interestingly, we find that the flux of the annihilation line in the co-moving frame keeps constant. These discoveries of the spectral line features shed new and important lights on the physics of GRB and relativistic jet. Copyright © 2024, The Authors. All rights reserved.

关键词： Gamma rays

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The environments of Type Ia supernovae with different relative equivalent width of Si II feature in their spectra

arXiv

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arXiv 2022年

作者： Meng, Xiang-Cun Zhang, Ju-Jia Zhao, Xu-Lin Li, Li-Ping Wang, Xiao-Feng Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China School of Science Tianjin University of Technology Tianjin300384 China University of Chinese Academy of Sciences Beijing100049 China Tsinghua University Beijing100084 China

Although type Ia supernovae are so important in many astrophysical field, e.g. in cosmology, their explosion mechanism and progenitor system are still unclear. In physics, the relative equivalent width (REW) of the Si II 635.5 nm absorption feature reflects the velocity interval of silicon in the supernova ejecta and then may provide constraints on the explosion mechanism of SNe Ia. In this paper, we divide the SNe Ia into broad line (BL) and normal line (NL) subsamples based on their REW of Si II 635.5 nm absorption lines around maximum light, and find that the BL SNe Ia have a dimmer mean brightness than NL ones, which possibly results from their different metallicities. However, based on the pixel statistics study on the environments of two subsamples, we do not find any significant potential difference on the environments between BL and NL SNe Ia, which implies that the explosion mechanism of SNe Ia could be independent of their progenitor populations. Copyright © 2022, The Authors. All rights reserved.

关键词： Supernovae

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Circumstellar Material Ejected Violently by A Massive Star Immediately before its Death

arXiv

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arXiv 2023年

作者： Zhang, Jujia Lin, Han Wang, Xiaofeng Zhao, Zeyi Li, Liping Liu, Jialian Yan, Shenyu Xiang, Danfeng Wang, Huijuan Bai, Jinming Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Key Laboratory of Radio Astronomy and Technology CAS A20 Datun Road Chaoyang District Beijing100101 China Department of Physics Tsinghua University Beijing100084 China Beijing Planetarium Beijing Academy of Science and Technology Beijing100044 China National Astronomical Observatories CAS Beijing100101 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China

Type II supernovae represent the most common stellar explosions in the Universe, for which the final stage evolution of their hydrogen-rich massive progenitors towards core-collapse explosion are elusive. The recent explosion of SN 2023ixf in a very nearby galaxy, Messier 101, provides a rare opportunity to explore this longstanding issue. With the timely high-cadence flash spectra taken within 1-5 days after the explosion, we can put stringent constraints on the properties of the surrounding circumstellar material around this supernova. Based on the rapid fading of the narrow emission lines and luminosity/profile of Hα emission at very early times, we estimate that the progenitor of SN 2023ixf lost material at a mass-loss rate M ≈ 6 ×10−4 M☉ a−1 over the last 2-3 years before explosion. This close-by material, moving at a velocity vw ≈ 55 km s−1, accumulates a compact CSM shell at the radius smaller than 7 × 1014 cm from the progenitor. Given the high mass-loss rate and relatively large wind velocity presented here, together with the pre-explosion observations made about two decades ago, the progenitor of SN 2023ixf could be a short-lived yellow hypergiant that evolved from a red supergiant shortly before the explosion. © 2023, CC BY-NC-ND.

关键词： Supernovae

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The origin of the soft x-ray excess in the seyfert 1.5 Galaxy ESO 362-G18

arXiv

引用

arXiv 2021年

作者： Zhong, Xiao-Gu Wang, Jian-Cheng 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

We review the Seyfert 1.5 Galaxy ESO 362-G18 for exploring the origin of the soft X-ray excess. The Warm Corona and Relativistic Reflection models are two main scenarios to interpret the soft X-ray excess in AGNs at present. We use the simultaneous X-ray observation data of XMM-Newton and NuSTAR on Sep. 24th, 2016 to perform spectral analysis in two steps. First, we analyze the time-average spectra by using Warm Corona and Relativistic Reflection models. Moreover, we also explore the Hybrid model, Double Reflection model and Double Warm Corona model. We find that both of Warm Corona and Relativistic Reflection models can interpret the time-average spectra well but cannot be distinguished easily based on the time-averaged spectra fit statistics. Second, we add the RMS and covariance spectra to perform the spectral analysis with time-average spectra. The result shows that the warm corona could reproduce all of these spectra well. The the hot, optical thin corona and neutral distant reflection will increase their contribution with the temporal frequency, meaning that the corona responsible for X-ray continuum comes from the inner compact X-ray region and the neutral distant reflection is made of some moderate scale neutral clumps. © 2021, CC BY.

关键词： Galaxies

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Further study of starspot activity and measurement of differential rotation for SZ Piscium

arXiv

引用

arXiv 2024年

作者： Xiang, Yue Gu, Shenghong Cameron, Collier Barnes, J.R. Cao, Dongtao Yunnan Observatories Chinese Academy of Sciences 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 School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China School of Physics and Astronomy University of St Andrews FifeKY16 9SS United Kingdom Department of Physical Sciences The Open University Walton Hall Milton KeynesMK7 6AA United Kingdom

We present a series of 9 Doppler images of the magnetically active K component of the RS CVn-type binary SZ Psc, based on the high-resolution spectroscopic data collected from 2014 to 2018. We apply least-squares deconvolution to all spectra to extract the average profiles with high signal-to-noise ratios (SNRs) for Doppler imaging. The surface maps of the K subgiant show starspots widely distributed along latitude and longitude. A prominent, non-axisymmetric polar spot around phase 0 is revealed by all images with sufficient phase coverage, which may be a stable feature on the K component. The starspots evolve in a time scale of one month. We have determined the surface shear rate of the K component from the starspot maps reconstructed 10 days apart in 2017 Nov–Dec, through the cross-correlation method. The surface differential rotation parameters are Ωeq = 1.591±0.002 rad d−1 and ΔΩ = 0.035±0.003 rad d−1. The absorption lines contributed from the tertiary component are detected in all LSD profiles of SZ Psc, and we measure the radial velocity of the binary system and the tertiary component to derive an elliptical orbit with a period of 1530 ± 3 days and a mass of 0.75 ± 0.06 M☉ for the tertiary component. Copyright © 2024, The Authors. All rights reserved.

关键词： Shear flow

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Searching for Multiple Populations in Star Clusters Using the China Space Station Telescope

引用

Research in Astronomy and Astrophysics 2022年第9期22卷 47-62页

作者： Chengyuan Li Zhenya Zheng Xiaodong Li Xiaoying Pang Baitian Tang Antonino P.Milone Yue Wang Haifeng Wang Dengkai Jiang School of Physics and Astronomy Sun Yat-sen UniversityDaxue RoadZhuhaiGuangdong 519082China CSST Science Center for the Guangdong-Hong Kong-Macao Greater Bay Area Zhuhai 519082China CAS Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical ObservatoryShanghai 200030China Division of Optical Astronomical Technologies Shanghai Astronomical ObservatoryShanghai 200030China Department of Physics Xi'an Jiaotong-Liverpool UniversitySuzhou 215123China Shanghai Key Laboratory for Astrophysics Shanghai Normal University100 Guilin Roadshanghai 200234China Dipartimento di Fisica e Astronomia“Galileo Galilei” Universitàdi PadovaVicolo dell'Osservatorio 31-35122PaduaItaly Istituto Nazionale di Astrofisica—Osservatorio Astronomico di Padova Italy Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 1001010China GEPI Observatoire de ParisUniversitéPSLCNRSPlace Jules Janssen F-92195MeudonFrance Yunnan Observatories Chinese Academy of Sciences396 YangfangwangGuandu DIstrictKuming 650216China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100101China

Multiple stellar populations(MPs) in most star clusters older than 2 Gyr, as seen by lots of spectroscopic and photometric studies, have led to a significant challenge to the traditional view of star formation. In this field, spacebased instruments, in particular the Hubble Space Telescope(HST), have made a breakthrough as they significantly improved the efficiency of detecting MPs in crowded stellar fields by images. The China Space Station Telescope(CSST) and the HST are sensitive to a similar wavelength interval, but the CSST covers a field of view which is about 5–8 times wider than that of HST. One of its instruments, the Multi-Channel Imager(MCI),will have multiple filters covering a wide wavelength range from NUV to NIR, making the CSST a potentially powerful tool for studying MPs in clusters. In this work, we evaluate the efficiency of the designed filters for the MCI/CSST in revealing MPs in different color–magnitude diagrams(CMDs). We find that CMDs made with MCI/CSST photometry in appropriate UV filters are powerful tools to disentangle stellar populations with different abundances of He, C, N, O and Mg. On the contrary, the traditional CMDs are blind to multiple populations in globular clusters(GCs). We show that CSST has the potential of being the spearhead instrument for investigating MPs in GCs in the next decades.

关键词： Galaxy:globular clusters general-stars abundances-techniques photometric

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Photometric Analysis of the Dwarf Nova Su Uma Based on Tess

SSRN

引用

SSRN 2023年

作者： Liu, Wei Shi, Xiang-Dong Fang, Xiao-Hui Wang, Qi-Shan Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming650216 China University of Chinese Academy of Sciences No.1 Yanqihu East Rd Huairou District Beijing101408 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China School of Mathematics Physics and Finance Anhui Polytechnic University Wuhu241000 China

We report the photometric analysis of SU UMa based on the observations ofthe Transiting Exoplanet Survey Satellite (TESS). TESS has released a large amount of data, which contain the light curves of a complete superoutburst and three normal outbursts of SU UMa. The evolution of superhumps during the superoutburst were analyzed. By using O - C method the three stages were determined and the superhump period for each stage were calculated. The mass ratio $q=0.137 (1)$ was estimated based on the stage A superhump method. A periodic oscillation with a period of 2.17(9) days was found in the superhump minimum O - C diagram, which is related to the precession of the accretion disk. We investigated the frequency information of QPOs in the light curves. An ultra-long period QPO of 0.18 days at the time of normal outburst and two ultra-long periods QPOs of 0.19 days and 0.285 days in quiescence were found. No QPO was found in the superoutburst. © 2023, The Authors. All rights reserved.

关键词： Stars

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A new approach to constraining properties of AGN host galaxies by combining image and SED decomposition: testing upon the MBH − M✶ relation

arXiv

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arXiv 2024年

作者： Yu, Haoran Fan, Lulu Han, Yunkun Sun, Weibin Zhang, Yihang Ding, Xuheng Xue, Yongquan CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Hefei230026 China School of Astronomy and Space Science University of Science and Technology of China Hefei230026 China Deep Space Exploration Laboratory Hefei230088 China Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China School of Physics and Technology Wuhan University Wuhan430072 China

The outshining light from active galactic nuclei (AGNs) poses significant challenges in studying the properties of AGN host galaxies. To address this issue, we propose a novel approach which combines image decomposition and spectral energy distribution (SED) decomposition to constrain properties of AGN host galaxies. Image decomposition allows us to disentangle optical flux into AGN and stellar components, thereby providing additional constraints on the SED models to derive more refined stellar mass. To test the viability of this approach, we obtained a sample of 24 X-ray selected type I AGNs with redshifts ranging from 0.73 to 2.47. We estimated the stellar masses for our sample and found that our results are generally consistent with earlier estimates based on different methods. Through examining the posterior distribution of stellar masses, we find that our method could derive better constrained results compared to previous SED decomposition methods. With the derived stellar masses, we further studied the MBH−M✶ relation of our sample, finding a higher intrinsic scatter in the correlation for our entire sample compared to the local quiescent correlation, which could be caused by a few "black hole monsters" in our sample. We propose that based on our method, future works could extend to larger samples of high-redshift AGN host galaxies, thereby enhancing our understanding of their properties. © 2024, CC BY.

关键词： Active Galactic Nuclei

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An investigation of the magnetic activity of HD 134319 based on TESS photometry and ground-based spectroscopy

arXiv

引用

arXiv 2022年

作者： Xu, Fukun Gu, Shenghong Ioannidis, Panogiotis Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China Hamburger Sternwarte Universität Hamburg Gojenbergsweg 112 HamburgD-21029 Germany

We present analysis of the starspot properties and chromospheric activity on HD 134319 using high precision photometry by TESS in sectors 14-16 (T1), 21-23 (T2) and high-resolution spectroscopy by OHP/ELODIE and Keck/HIRES during years 1995-2013. We applied a two-spot model with GLS determined period P = 4.436391 ± 0.00137 day to model chunks sliding over TESS light curve, and measured relative equivalent widths of Ca II H and K, Hβ and Hα emissions by subtracting overall spectrum from individual spectrum. It was found that a two-spot configuration, i.e. a primary, slowly evolving and long-lasting spot (P) plus a secondary and rapidly evolving spot S, was capable of explaining the data, although the actual starspot distribution is unable to derived from collected data. Despite the spot radius-latitude degeneracy revealed in the best-fit solutions, a sudden alternation between P and S radii followed by gradual decrease of S in T1 and the decrease of both P and S from T1 to T2 were significant, corresponding to the evolution of magnetic activity. Besides, S revealed rotation and oscillatory longitude migration synchronized to P in T1, but held much larger migration than P in T2. This might indicate the evolution of internal magnetic configuration. Chromospheric activity indicators were found to tightly correlated with each other and revealed rotational modulation as well as a long-term decrease of emissions, implying the existence and evolution of magnetic acitivity on HD 134319. © 2022, CC0.

关键词： Photometry

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Deep search for gamma-ray emission from the accreting X-ray pulsar 1A 0535+262

arXiv

引用

arXiv 2023年

作者： Hou, X. Zhang, W. Torres, D.F. Ji, L. Li, J. Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Campus UAB Barcelona08193 Spain Barcelona08034 Spain BarcelonaE-08010 Spain School of Physics and Astronomy Sun Yat-Sen University Zhuhai519082 China CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Hefei China School of Astronomy and Space Science University of Science and Technology of China Hefei China

Binary systems are a well-established subclass of gamma-ray sources. The high mass X-ray binary pulsar 1A 0535+262 has been considered to be a possible gamma-ray emitter for a long time, although former gamma-ray searches using Fermi-LAT and VERITAS data resulted in upper limits only. We aim at a deep search for gammaray emission and pulsations from 1A 0535+262 using more than 13 years of FermiLAT data. The analysis was performed for both the whole Fermi-LAT data set, as well as for the X-ray outbursts that 1A 0535+262 has experienced since the launch of Fermi. Various X-ray observations have been used to generate the ephemeris for the pulsation search. We also investigate the long-term gamma-ray flux variability and perform orbital phase-resolved analysis for the outbursts. We did not detect any steady or pulsed gamma-ray emission from 1A 0535+262 during the whole Fermi-LAT mission span or its X-ray outbursts. We thus derived the deepest gamma-ray luminosity upper limits to date at the 95% confidence level to be around (2.3−4.7)×1032 erg s−1 depending on different spectral indices assumed, which results in a ratio of Lγ to LX (2−150 keV) being (1.9−3.9)×10−6 Copyright © 2023, The Authors. All rights reserved.

关键词： Gamma rays

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