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The 2175 Ã bump features in FeLoBAL quasars: One indicator of MW-like dust in the nuclear region of quasars

Astronomy and Astrophysics 2022年 663卷

作者： Zhang, Shaohua Ge, Jian Ji, Tuo Jiang, Peng Luo, Zhijian Pan, Xiang Shi, Xiheng Shu, Chenggang Wang, Jianguo Xiao, Hubing Zhou, Hongyan Shanghai Key Lab For Astrophysics Shanghai Normal University Shanghai200234 China Key Laboratory For Research In Galaxies And Cosmology Shanghai Astronomical Observatory Chinese Academy Of Sciences Shanghai200030 China Key Laboratory Of Polar Science Polar Research Institute Of China Ministry Of Natural Resources Shanghai200136 China Key Laboratory For The Structure And Evolution Of Celestial Objects Yunnan Observatories Chinese Academy Of Sciences Kunming Yunnan650011 China Key Laboratory For Research In Galaxies And Cosmology Department Of Astronomy University Of Science And Technology Of China Chinese Academy Of Sciences Hefei Anhui230026 China School Of Astronomy And Space Science University Of Science And Technology Of China Hefei Anhui230026 China

To investigate the properties of dust in the nuclear region of quasars, we explored the extinction curves of the iron low-ionisation broad absorption line (FeLoBAL) quasar SDSS J163004.29+311957.6 and its two analogues. The parametrised extinction curves indicated the Milky Way-like 2175 Ã bump features in underlying extinction, which are similar to those seen in the Local Group and in a subset of high-redshift star-forming galaxies. Compared to the bump features in the Large Magellanic Cloud (LMC), the detections in this work are much closer to those in the Milky Way (MW). These bump features, as well as those in the high-and low-ionisation broad absorption line (BAL) quasars with 2175 Ã bumps, are probably the counterpart of the 2175 Ã bump features in the quasar environment. This type of dust grain is generally small, easily disrupted by high-energy photons, and has difficulty surviving in the radiation field of the active galactic nucleus. However, due to the presence of absorption-line outflows, the 2175 Ã bump feature in quasars, which should be rare, is seen many times in BAL quasars. The shielding effect of outflow clouds allows the MW-like dust grains to be assembled or extends the survival period in the quasar nuclear region. The process and physical and chemical conditions deserve further observational study and investigation. © 2022 ESO.

关键词： Dust

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Temporal Analysis of GRB Precursors in the Third Swift-BAT Catalog

arXiv

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arXiv 2022年

作者： Li, Liande Mao, Jirong Yunnan Observatories Chinese Academy of Sciences Yunnan Province Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

We select 52 long gamma-ray bursts(GRBs) having the precursor activity in the third Swift-BAT catalog. Each episode shown in both the precursors and the main bursts is fitted by the Norris function. We systematically analyze the temporal properties for both the precursors and the main bursts. We do not find any significant difference between the temporal profile of the precursor and that of the main burst. The photon count of the precursor is related to that of the main burst. It is indicated that the precursor and the main burst might have the same physical origin, as the precursor and the main burst follow the same τp−ω relation. However, we do not find the explicit relation between the energy release of the precursor and the quiescent time. Some theoretical models, such as the fallback collapsar scenario and the jet-cocoon scenario, may be helpful to explain the GRB-precursor phenomena. © 2022, CC BY.

关键词： Stars

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Timing analysis of EXO 2030+375 during its 2021 giant outburst observed with Insight-HXMT

arXiv

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arXiv 2023年

作者： Fu, Yu-Cong Song, L.M. Ding, G.Q. Ge, M.Y. Tuo, Y.L. Zhang, S. Zhang, S.N. Hou, X. Qu, J.L. Zhang, J. Zhang, L. Bu, Q.C. Huang, Y. Ma, X. Zhou, X. Yan, W.M. Yang, Z.X. Lu, X.F. Li, T.M. Xu, Y.C. Wang, P.J. Xiao, S.H. Liu, H.X. Ren, X.Q. Du, Y.F. Zhao, Q.X. Xiao, Y.X. Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi Xinjiang830011 China University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100049 China Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Institut für Astronomie und Astrophysik Kepler Center for Astro and Particle Physics Eberhard Karls Universität Sand 1 Tübingen72076 Germany Key Laboratory of Radio Astronomy Chinese Academy of Sciences Nanjing210008 China Xinjiang Key Laboratory of Radio Astrophysics Urumqi830011 China

We report the evolution of the X-ray pulsations of EXO 2030+375 during its 2021 outburst using the observations from Insight-HXMT. Based on the accretion torque model, we study the correlation between the spin frequency derivatives and the luminosity. Pulsations can be detected in the energy band of 1–160 keV. The pulse profile evolves significantly with luminosity during the outburst, leading to that the whole outburst can be divided into several parts with different characteristics. The evolution of the pulse profile reveals the transition between the super-critical (fan-beam dominated) and the sub-critical accretion (pencil-beam dominated) mode. From the accretion torque model and the critical luminosity model, based on a distance of 7.1 kpc, the inferred magnetic fields are (0.41 − 0.74) × 1012 G and (3.48 − 3.96) × 1012 G, respectively, or based on a distance of 3.6 kpc, the estimated magnetic fields are (2.4 − 4.3) × 1013 G and (0.98 − 1.11) × 1012 G, respectively. Two different sets of magnetic fields both support the presence of multipole magnetic fields of the NS. © 2023, CC BY-NC-ND.

关键词： Luminance

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The Common Envelope evolution Outcome-A Case Study on Hot Subdwarf B Stars

arXiv

引用

arXiv 2022年

作者： Ge, Hongwei Tout, Christopher A. Chen, Xuefei Kruckow, Matthias U. Chen, Hailiang Jiang, Dengkai Li, Zhenwei Liu, Zhengwei Han, Zhanwen Yunnan Observatories Chinese Academy of Sciences 396 YangFangWang Guandu District Kunming650216 China Institute of Astronomy The Observatories University of Cambridge Madingley Road CambridgeCB3 0HA United Kingdom Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650216 China

Common envelope evolution (CEE) physics plays a fundamental role in the formation of binary systems, such as mergering stellar gravitational wave sources, pulsar binaries and type Ia supernovae. A precisely constrained CEE has become more important in the age of large surveys and gravitational wave detectors. We use an adiabatic mass loss model to explore how the total energy of the donor changes as a function of the remnant mass. This provides a more self-consistent way to calculate the binding energy of the donor. For comparison, we also calculate the binding energy through integrating the total energy from the core to the surface. The outcome of CEE is constrained by total energy conservation at the point at which both component's radii shrink back within their Roche lobes. We apply our results to 142 hot subdwarf binaries. For shorter orbital period sdBs, the binding energy is highly consistent. For longer orbital period sdBs in our samples, the binding energy can differ by up to a factor of 2. The CE efficiency parameter βCEbecomes smaller than αCEfor the final orbital period log10Porb=d >-0.5. We also find the mass ratios log10q and CE efficiency parameters log10αCEand log10βCElinearly correlate in sdBs, similarly to De Marco et al. (2011) for post-AGB binaries. © 2022, CC0.

关键词： Binding energy

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Transient phenomena from gas-erupting neutron stars

arXiv

引用

arXiv 2021年

作者： Li, Huiquan 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

Starquakes probably occur in rapidly spinning or ultra high field neutron stars. In this article, we argue that highly compressed gas containing electron-positron pairs could evaporate and erupt from inside the neutron star when a crack forms and then heals during a starquake. Under the influence of the existing oscillation modes of the star, the crack may have sufficiently large size and long lifetime. An appropriate amount of gas can erupt into the magnetosphere with relativistic and nearly uniform velocity, producing various transient and bursting phenomena. © 2021, CC0.

关键词： Stars

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Observational constraints on Rastall gravity from rotation curves of low surface brightness galaxies

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Chinese Physics C 2020年第8期44卷 217-224页

作者： Meirong Tang Zhaoyi Xu Jiancheng Wang Yunnan Observatories Chinese Academy of Sciences396 YangfangwangGuandu DistrictKunming 650216China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences396 YangfangwangGuandu DistrictKunming 650216China Center for Astronomical Mega-Science Chinese Academy of Sciences20A Datun RoadChaoyang DistrictBeijing 100012China University of Chinese Academy of Sciences Beijing 100049China

Rastall gravity is a modification of Einstein's general relativity in which the energy-momentum conservation is not satisfied and depends on the gradient of the Ricci *** is currently in dispute whether Rastall gravity is equivalent to general relativity(GR).In this work,we constrain the theory using the rotation curves of low surface brightness(LSB)spiral *** fitting the rotation curves of LSB galaxies,we obtain parameterβof the Rastall ***βvalues of LSB galaxies satisfy the weak energy condition(WEC)and strong energy condition(SEC).Combining theβvalues of type Ia supernovae and the gravitational lensing of elliptical galaxies on Rastall gravity,we conclude that Rastall gravity may be equivalent to general relativity.

关键词： Rastall gravity energy condition LSB galaxies

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A photometric study of the high-mass-ratio contact binary AV Puppis

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Research in Astronomy and Astrophysics 2019年第12期19卷 217-222页

作者： Quan-Wang Han Li-Fang Li Deng-Kai Jiang Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences.Kunming 650216China University of Chinese Academy of Sciences Beijing 100049China

The multi-color photometric light curves for contact binary AV Puppis(AV Pup) in VRcIc bandpasses are presented and analyzed by using the 2013 version of the Wilson-Devinney(W-D) *** solutions suggest that AV Pup is a peculiar A-subtype W UMa contact binary with a high mass ratio(q = m2/m1 = 0.896) and a low fill-out factor(f = 10%). Combining our newly determined times of minimum with those collected from literatures, the orbital period changes of this system are investigated. The O-C analysis indicates that the orbital period of AV Pup is increasing at a rate of d P/dt = 4.83 × 10-7 days yr-1, which can be explained by mass transfer from the less massive component to the more massive one.

关键词： techniques:photometric stars:magnetic field stars:individual:AV Pupis

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Testing Colour-magnitude Pattern as A Method in the Search for Changing-Look AGNs

arXiv

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arXiv 2024年

作者： Zhu, Li-Tao Wang, Zhongxiang Devanand, P.U. Gupta, Alok C. Dogra, Karan Li, Jie Zhang, Ju-Jia Ji, Shun-Hao Sun, Si-Si Department of Astronomy School of Physics and Astronomy Yunnan University Kunming650091 China Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai200030 China Manora Peak Nainital263001 India Department of Applied Physics/Physics Mahatma Jyotiba Phule Rohilkhand University Bareilly243006 India Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Hefei230036 China School of Astronomy and Space Science University of Science and Technology of China Hefei230026 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China

We develop a simple method to search for changing-look (CL) active galactic nucleus (AGN) candidates, and conduct a test run. In this method, optical variations of AGNs are monitored and CL-AGNs may appear to have a pattern of being bluer when in brightening flare-like events. Applying this method, previously-classified type 2 AGNs that show the bluer-when-brighter (BWB) pattern are selected. Among more than ten thousands type 2 AGNs classified in the Sloan Digital Sky Survey (SDSS), we find 73 candidates with possibly the strongest BWB pattern. We note that 13 of them have previously been reported as CL-AGNs. We have observed nine candidates, and found that five among them showed the CL transition from type 2 to type 1. In addition, we also test extending the selection to previously-classified type 1 AGNs in the SDSS by finding sources with a possible redder-when-brighter pattern, but none of the three sources observed by us is found to show the transition from type 1 to type 2. We discuss the variation properties in both the success and failure cases, and plan to observe more candidates selected with the method. From the observational results, a detailed comparison between the CL-AGNs and none CL-AGNs will help quantitatively refine the selection criteria and in turn allow us to configure the general properties of CLAGNs. © 2024, CC BY.

关键词： Active Galactic Nuclei

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The preliminary statistical analysis of LAMOST DR8 low resolution AFGK stars

arXiv

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arXiv 2022年

作者： Chen, Yan hui Li, Guang Wei Shu, Hong Institute of Astrophysics Chuxiong Normal University Chuxiong675000 China National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Physics and Electronical Science Chuxiong Normal University Chuxiong675000 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P.O. Box 110 Kunming650011 China

We download the LAMOST DR8 low resolution catalog 6,478,063 AFGK tpye stars and plot the figures of effective temperature, gravitational acceleration, and metal abundance. Some small and medium mass stars are evolved from pre-main sequence or main sequence stage to planetary nebula stage or white dwarf stage by the stellar evolution code MESA. We analyze the observed statistical data and model calculation results, and then obtain some basic conclusions preliminarily. Most red giant and asymptotic giant stars with logg less than 0.85 have poor metal abundance. Most hot A type main-sequence stars are metal rich stars with logg from 3.5 to 4.5. The conclusions are reasonable within a certain error range. The theory of a gap area in the H-R diagram for stellar evolutions of medium mass stars is reflected in the statistical figures. The central core hydrogen burning stage and the central core helium burning stage correspond to the peak structures in the gravitational acceleration statistical figures respectively. The metal abundances among A, F, G, and K type stars have a wide distribution. We can not simply replace the metal abundances of these stars with the metal abundance of the Sun when doing a fine research work. Copyright © 2022, The Authors. All rights reserved.

关键词： Metals

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Physical properties of hyperluminous, dust-obscured quasars at z ∼ 3: multiwavelength Spectral Energy Distribution analysis and cold gas content revealed by ALMA

arXiv

引用

arXiv 2024年

作者： Sun, Weibin Fan, Lulu Han, Yunkun Knudsen, Kirsten K. Chen, Guangwen Zhang, Hong-Xin 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 Department of Space Earth and Environment Chalmers University of Technology Onsala Space Observatory OnsalaSE-439 92 Sweden

We present a UV to millimeter spectral energy distribution (SED) analysis of 16 hyperluminous, dust-obscured quasars at z ∼ 3, selected by the Wide-field Infrared Survey Explorer. We aim to investigate the physical properties of these quasars, with a focus on their molecular gas content. We decompose the SEDs into three components: stellar, cold dust, and active galactic nucleus (AGN). By doing so, we are able to derive and analyze the relevant properties of each component. We determine the molecular gas mass from CO line emission based on Atacama Large Millimeter/submillimeter Array (ALMA) observations. By including ALMA observations in the multiwavelength SED analysis, we derive the molecular gas fractions, gas depletion timescales, and star formation efficiencies (SFEs). Their sample median and 16th-84th quartile ranges are fgas ∼ 0.33+0.33−0.17, tdepl ∼ 39+85−28 Myr, SFE ∼ 297+659−195 K km s−1 pc−2. Compared to main-sequence galaxies, they have a lower molecular gas content and higher SFEs, similar to quasars in the literature. This suggests that the gas in these quasars is rapidly depleted, likely as the result of intense starburst activity and AGN feedback. The observed correlations between these properties and the AGN luminosities further support this scenario. Additionally, we infer the black hole to stellar mass ratio and black hole mass growth rate, which indicate a significant central black hole mass assembly over short timescales. Our results are consistent with the scenario that our sample represents a short transition phase toward unobscured quasars. Copyright © 2024, The Authors. All rights reserved.

关键词： Physical properties

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