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

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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

Supermassive Black Hole and Broad-line Region in NGC~5548: Results from Five-season Reverberation Mapping

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arXiv 2022年

作者： Lu, Kai-Xing Bai, Jin-Ming Wang, Jian-Min Hu, Chen Li, Yan-Rong Du, Pu Xiao, Ming Feng, Hai-Cheng Li, Sha-Sha Wang, Jian-Guo Zhang, Zhi-Xiang Huang, Ying-Ke Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Key Laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences 19B Yuquan Road Beijing100049 China Department of Astronomy Xiamen University Fujian Xiamen361005 China Multi-disciplinary Research Division Institute of High Energy Physics Chinese Academy of Sciences 19B Yuquan Road Beijing100049 China

NGC 5548 is one of the active galactic nuclei (AGN) selected for our long-term spectroscopic monitoring with the Lijiang 2.4 m telescope, aiming at investigating the origin and evolution of the broad-line regions (BLRs), accurately measuring the mass of the supermassive black holes (SMBHs), and understanding structure and evolution of the AGN. We have performed five-season observations for NGC 5548 with the median sampling interval ranging from 1.25 to 3 days. The light curves of the 5100 Å continuum and broad emission lines are measured after subtracting contamination of the host galaxy starlight. The time lags of the broad He II, He I, Hγ, and Hβ lines with respect to the 5100 Å continuum are obtained for each season and their mean time lags over the five seasons are 0.69, 4.66, 4.60, 8.43 days, respectively. The Hγ and Hβ velocity-resolved lag profiles in the seasons of 2015, 2018, 2019, and 2021 are constructed, from which an "M-shaped" structure is found in 2015 but disappears after 2018. Our five-season reverberation mapping (RM) yields an averaged virial SMBH mass of M•/107Mo = 14.22, with a small standard deviation of 1.89. By combining the previous 18 RM campaigns and our five-season campaign for NGC 5548, we find that there exists a time lag of 3.5 years between the changes in the BLR size and optical luminosity. In addition, we also construct the BLR radius−luminosity relation and the virial relation for NGC 5548. © 2022, CC BY.

关键词： Active Galactic Nuclei

Fundamental parameters for dEB SB2 binary system J064726.39+223431.6

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arXiv 2022年

作者： Kovalev, Mikhail Wang, Song Chen, Xuefei Han, Zhanwen Yunnan Observatories China Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Sternberg Astronomical Institute M. v. Lomonosov Moscow State University Leninskie Gory Moscow119991 Russia Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China

We present a study of the detached eclipsing binary J064726.39+223431.6 using spectra from the LAMOST medium-resolution spectra and TESS photometry. We use full-spectrum fitting to derive radial velocities and spectral parameters: (formula presented) and (formula presented). The orbital solution and light curve analysis suggest that it is a close pair of fast rotating stars on a circular orbit. We measure their masses to be (formula presented) and their radii to be (formula presented) resulting in surface gravities of log (g) (formula presented). Theoretical models cannot match all of these properties, predicting significantly higher Teff for a given metallicity. The derived age of the system is 1.56 Gyr, which indicates that both components are younger than Sun, which contradicts to much longer orbit’s circularisation timescale. Copyright © 2022, The Authors. All rights reserved.

关键词： Stars

Timing properties of the X-ray accreting pulsar RX J0440.9+4431 studied with Insight-HXMT and NICER

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arXiv 2023年

作者： Li, P.P. Tao, L. Tuo, Y.L. Ge, M.Y. Kong, L.D. Zhang, L. Bu, Q.C. Ji, L. Qu, J.L. Zhang, S. Zhang, S.N. Huang, Y. Ma, X. Ye, W.T. Zhao, Q.C. Ma, R.C. Zhao, S.J. Hou, X. Yang, Z.X. Wang, P.J. Jia, S.M. Shui, Q.C. Guan, J. Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China Uinversity of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100049 China Institut für Astronomie und Astrophysik Kepler Center for Astro and Particle Physics Eberhard Karls Universität Sand 1 TübingenD-72076 Germany School of Physics and Astronomy Sun Yat-sen University Zhuhai519082 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 School of Physics and Optoelectronic Engineering Shandong University of Technology Zibo255000 China

RX J0440.9+4431, a Be/X-ray binary, had its brightest outburst in 2022 since its discovery, with a peak X-ray flux of 2.25 Crab (as recorded by Swift/BAT, 15-50 keV). We analyze the timing properties of this giant outburst using data from Insight-HXMT and NICER, focusing on the evolution of the pulse profile and pulse fraction. We observe that when the luminosity reached around ~3 × 1037 erg s−1, a transition from double-peaked to single-peaked pulse profiles occurred across the energy range, with the peak of the low-energy profile aligning gradually with the peak of the high-energy profile. This change indicates a transition from subcritical to supercritical accretion. Additionally, we found a concave in the pulse fraction as a function of energy around 20-30 keV throughout the entire outburst period. Compared to the low luminosity, the concave becomes weaker in high luminosities, and overall, the pulse fraction is higher. We propose that this concave could be caused by the scattering of high-energy photons by the atmosphere of a neutron star, leading to a dilution of the pulse fraction. As the accretion reaches the supercritical state, the accretion column height increases, resulting in a larger direct component of strongly beamed X-ray flux, and an elevated pulse fraction. Copyright © 2023, The Authors. All rights reserved.

关键词： Luminance

Photometric investigations on two totally eclipsing contact binaries:V342 UMa and V509 Cam

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Research in Astronomy and Astrophysics 2019年第10期19卷 75-86页

作者： Kai Li Qi-Qi Xia Jin-Zhong Liu Yu Zhang Xing Gao Shao-Ming Hu Di-Fu Guo Xu Chen Yuan Liu Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space Sciences Shandong University Weihai 264209 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650216 China Xinjiang Astronomical Observatory Chinese Academy of Sciences Urumqi 830011 China Qilu Institute of Technology Jinan 250200 China

By analyzing two sets of complete BV Rc Ic light curves for V342 UMa and three sets of complete BV Rc Ic light curves for V509 Cam, we determined that the two systems are both W-subtype contact binaries and that V342 UMa manifests a shallow contact configuration, while V509 Cam exhibits a medium contact configuration. Given that both of them are totally eclipsing binaries, the physical parameters derived only by the photometric light curves are reliable. Meanwhile, the period changes of the two targets were analyzed based on all available eclipsing times. We discovered that V342 UMa shows long-term period decrease with a rate of-1.02(±0.54)× 10^-7 d yr^-1 and that V509 Cam displays long-term period increase with a rate of 3.96(±0.90)× 10^-8 d yr^-1. Both the conservative mass transfer and angular momentum loss via magnetic stellar winds can be used to interpret the long-term period decrease of V342 UMa. The longterm period increase of V509 Cam can be explained by mass transfer from the less massive star to the more massive one. The absolute parameters of the two binaries were estimated according to their Gaia distances and our derived photometric solution results. This method can be extended to other contact binaries without radial velocities but with reliable photometric solutions. Their evolutionary states were investigated and we found that they reveal properties that are identical to other W-subtype contact systems.

关键词： stars binaries close-stars eclipsing-stars individual (V342UMa, V509Cam)

Interference location using an improved TDOA algorithm with antenna array and beamforming

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Interference location using an improved TDOA algorithm with ...

International Conference on Intelligent Computing, Communication and Devices, ICCD 2017

作者： Miao, Sheng Zhou, Hua Yang, Hongji Southwest Forestry University Kunming China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming China Centre for Creative Computing Bath Spa University Bath United Kingdom

ISBN: (纸本)9789811089435

Time Difference of Arrival (TDOA) is a popular interference location algorithm in the radio astronomy monitoring environment, where radio interference source may interfere with the performance of the receiver. However, with the geomagnetic white noise interference, interference detection is hard for a normal TDOA algorithm. In this paper, an improved interfere detection method is proposed. Single receiving antenna has been replaced by array antenna, and the adaptive beamforming algorithm is used in data preprocessing. A composite signal after beam-forming as an input of TDOA algorithm. The experiment shows that, comparing with the traditional TDOA algorithm and using beamforming, the location of the interference has been enhanced about 10 m for normal in the about 5 km. © Springer Nature Singapore Pte Ltd. 2019.

关键词： Beamforming

Unprecedented Central Engine "Breathing" Phenomenon in an Active Supermassive Black Hole

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arXiv 2024年

作者： Zhou, Shuying Sun, Mouyuan Feng, Hai-Cheng Li, Sha-Sha Xue, Yongquan Wang, Jun-Xian Cai, Zhen-Yi Bai, Jin-Ming Li, Danyang Guo, Hengxiao Liu, H.T. Lu, Kai-Xing Mao, Jirong Marculewicz, Marcin Wang, Jian-Guo Department of Astronomy Xiamen University Fujian Xiamen361005 China SHAO-XMU Joint Center for Astrophysics Fujian Xiamen361005 China 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 Beijing100012 China Department of Astronomy University of Science and Technology of China Anhui Hefei230026 China School of Astronomy and Space Science University of Science and Technology of China Anhui Hefei230026 China High School Affiliated to Yunnan Normal College Yunnan Kunming650506 China Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China

Resolving the inner structures of active galactic nuclei (AGNs) provides the "standard ruler" to measure the parallax distances of the Universe and a powerful way to weigh supermassive black holes (SMBHs). Thanks to time-domain observations, it is possible to use the reverberation mapping (RM) technique to measure time delays between different light curves that probe the structures of the SMBH accretion disks and broad line regions (BLRs), which are otherwise often too compact to be spatially resolved with current facilities for most AGNs. Despite decades of RM studies, the critical physical process that controls the structures of SMBH accretion disk and BLR and their temporal evolution remains unclear. Here we report the variation of the SMBH accretion disk structure of NGC 4151, a highly variable AGN, in response to changes in luminosity within ∼ 6 years. In the high-flux state, the time delays measured from our continuum RM with high-cadence (∼ 2 days) spectroscopy are 3.8+1.8−1.0 times larger than that in the low-flux state and 14.9 ± 2.0 times longer than the classical standard thin disk (SSD) prediction. This result provides the first piece of direct evidence that the SMBH disk structure "breathes" in highly-variable AGN manifestations. The significant time-delay change severely challenges the popular X-ray reprocessing of the classical SSD model, with or without contributions from BLRs. More importantly, the continuum time delays can be comparable with the time delay between the light curves of the broad Hβ emission line and the nearby optical continuum, and the latter is commonly used to calculate the BLR sizes. Hence, the BLR sizes are significantly underestimated if the continuum time delays are not properly considered. This underestimation introduces up to 0.3 dex systematic uncertainties on RM SMBH masses and BLR parallax distances. Our findings underscore that simultaneous continuum and BLR RM studies are vital for better deciphering the SMBH mass growt

关键词： Reverberation

One Reliable Method for Stellar Parameter Determination Based on Space Photometry and the Phoenix Spectral Library

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SSRN

SSRN 2022年

作者： Liu, Yisi Gu, Shenghong Perdelwitz, Volker Liu, Jing Yunnan Observatories Chinese Academy of Sciences Yunnan Kunming650216 China National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Yunnan Kunming650216 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China Hamburger Sternwarte Gojenbergsweg 112 Hamburg21029 Germany Department of Physics Ariel University Ariel40700 Israel

For a survey project, to get precise determination on parameters of stars is quite important. Although the second data release of Gaia provided stellar parameters for an unprecedented number of stars, due to the proximity of the Gaia passbands, the reliability of these parameters is still not unshakeable, especially for specific targets. In order to establish a reliable estimation of stellar parameters such as the effective temperature and so on, we are currently developing an algorithm which compares the absolute fluxes of all Gaia passbands, combined with those from the WISE mission, to PHOENIX spectra. Results have shown that a broader wavelength range enables a reliable determination of these parameters. Furthermore, the effective temperature we derived has a better precision than Gaia’s one, which shows the good performance of PHOENIX model. © 2022, The Authors. All rights reserved.

关键词： Surveys

Close binary black hole in a radio-quiet quasar: a candidate of Nano-Hertz gravitational wave emitter

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Research Square

Research Square 2021年

作者： Feng, Hai-Cheng Liu, Hong-Tao Bai, Jin-Ming Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan650011 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming Yunnan650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China

Close supermassive binary black holes (SMBBHs) with separations less than ∼ 0.1 parsec are expected to be Nano-Hertz gravitational wave sources1. SMBBH systems should exhibit periodic variability2. However, periodic variability in radio-loud quasars may be interpreted with the jet model3. Here we report the detection of a robust periodic signal in the optical variability of the radio-quiet quasar PG 0923+201 with an observed period of 726.8 ± 4.7 days, obtained from the sinusoid-like light curve of a temporal baseline of about 9 years. This periodicity is probably from a close SMBBH with a total mass of 109.3 solar masses and a separation of ∼ 0.01 parsec, implying relativistic orbital speeds. Such a system has passed through the well-known "final parsec problem" of SMBBH systems4, and the Nano-Hertz gravitational wave radiation becomes significant. The ratio of the separation between these two black holes to the broad-line region size is ∼ 0.1. A close SMBBH is also suggested by this small ratio and the spectral properties of Balmer broad lines in this quasar. This radio-quiet quasar is a candidate emitter of Nano-Hertz gravitational waves at a frequency of about 30 Nano-Hertz. © 2021, CC BY.

关键词： Gravity waves