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Alma imaging of the CO (7−6) line emission in the submillimeter galaxy less 073 at redshift 4.755

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arXiv 2020年

作者： Zhao, Yinghe Lu, Nanyao Díaz-Santos, Tanio Gao, Yu Xu, C. Kevin Charmandaris, Vassilis Inami, Hanae Rigopoulou, Dimitra Sanders, David B. Huang, Jiasheng Wang, Zhong Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Center for Astronomical Mega-Science CAS 20A Datun Road Chaoyang District Beijing100012 China National Astronomical Observatories of China Chinese Academy of Sciences Beijing100012 China China-Chile Joint Center for Astronomy Chinese Academy of Sciences Camino El Observatorio 1515 Las Condes Santiago Chile Núcleo de Astronomía de la Facultad de Ingeniería Universidad Diego Portales Av. Ejército Libertador 441 Santiago Chile Department of Astronomy Xiamen University XiamenFujian361005 China Department of Physics University of Crete HeraklionGR-71003 Greece IAASARS National Observatory of Athens PenteliGR-15236 Greece Hiroshima Astrophysical Science Center Hiroshima University 1-3-1 Kagamiyama Higashi-HiroshimaHiroshima739-8526 Japan Department of Physics University of Oxford Keble Road OxfordOX1 3RH United Kingdom University of Hawaii Institute for Astronomy 2680 Wood-lawn Drive HonoluluHI96822 United States

In this paper we present our imaging observations on the CO (7−6) line and its underlying continuum emission of the young submillimeter galaxy LESS 073 at redshift 4.755, using the Atacama Large Millimeter/submillimeter Array (ALMA). At the achieved resolution of ∼1′′.2 × 0′′.9 (8 × 6 kpc2), the CO (7−6) emission is largely unresolved (with a deconvolved size of 1′′.1(±0′′.5) × 0′′.9(±0′′.8).), and the continuum emission is totally unresolved. The CO (7−6) line emission has an integrated flux of 0.86 ± 0.08 Jy km s−1, and a line width of 343 ± 40 km s−1. The continuum emission has a flux density of 0.51 mJy. By fitting the observed far-infrared (FIR) spectral energy distribution of LESS 073 with a single-temperature modified blackbody function, we obtained a dust temperature Tdust = 57.6 ± 3.5 K, 60-to-100 µm flux density ratio f60/f100 = 0.86 ± 0.08, and total infrared luminosity LIR = (5.8 ± 0.9) × 1012 L☉. The SED-fit-based f60/f100 is consistent with those estimated from various line ratios as advocated by our earlier work, indicating that those proposed line-ratio-based method can be used to practically derive f60/f100 for high-z sources. The total molecular gas mass of LESS 073 is (3.3 ± 1.7) × 1010 M☉, and the inferred gas depletion time is about 43 Myr. Copyright © 2020, The Authors. All rights reserved.

关键词： Galaxies

Evolving ONe WD+He star systems to intermediate-mass binary pulsars

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arXiv 2018年

作者： Liu, D. Wang, B. Chen, W. Zuo, Z. Han, Z. Key Laboratory for Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy of Sciences Kunming 650216 China University of Chinese Academy of Sciences Beijing100049 China Center for Astronomical Mega-Science Chinese Academy of Sciences Beijing100012 China School of Physics and Electrical Information Shangqiu Normal University Shangqiu476000 China School of Science Xi'an Jiaotong University Xi'an710049 China

It has been suggested that accretion-induced collapse (AIC) is a non-negligible path for the formation of the observed neutron stars (NSs). An ONe white dwarf (WD) that accretes material from a He star may experience AIC process and eventually produce intermediate-mass binary pulsars (IMBPs), named as the ONe WD+He star scenario. Note that previous studies can only account for part of the observed IMBPs with short orbital periods. In this work, we investigate the evolution of about 900 ONe WD+He star binaries to explore the distribution of IMBPs. We found that the ONe WD+He star scenario could form IMBPs including pulsars with 5-340ms spin periods and 0.75-1.38Mo WD companions, in which the orbital periods range from 0.04 to 900 d. Compared with the 20 observed IMBPs, this scenario can cover the parameters of 13 sources in the final orbital period-WD mass plane and the Corbet diagram, most of which has short orbital periods. We found that the ONe WD+He star scenario can explain almost all the observed IMBPs with short orbital periods. This work can well match the observed parameters of PSR J1802-2124 (one of the two precisely observed IMBPs), providing a possible evolutional path for its *** also speculate that the compact companion of HD 49798 (a hydrogen depleted sdO6 star) may be not a NS based on the present work. Copyright © 2018, The Authors. All rights reserved.

关键词： White dwarfs

SDSS J094635.06+101706.1: A redshift one, very radio-loud, γ-ray emitting narrow-line Seyfert 1 galaxy

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arXiv 2019年

作者： Yao, Su Komossa, S. Liu, Wen-Juan Yi, Weimin Yuan, Weimin Zhou, Hongyan Wu, Xue-Bing Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China Max-Planck Institut für Radioastronomie Auf dem Hügel 69 Bonn53121 Germany Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Department of Astronomy & Astrophysics Pennsylvania State University 525 Davey Lab University ParkPA16802 United States Key Laboratory of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China CAS Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy USTC Hefei Anhui230026 China SOA Key Laboratory for Polar Science Polar Research Institute of China 451 Jinqiao Road Shanghai200136 China Department of Astronomy School of Physics Peking University Beijing100871 China

As hybrids of narrow-line Seyfert 1 (NLS1) galaxies and blazars, γ-ray emitting NLS1s are important probes of jet physics in the high Eddington-ratio regime. Only very few of them are known to date;the majority of them below redshift z = 0.5. Here we present the identification of the γ-ray emitting AGN TXS 0943+105 (SDSS J094635.06+101706.1) as a high-redshift NLS1 galaxy. It turns out to be one of the radio-loudest NLS1s known, highly variable at all wavelengths, and shows widely extended radio emission at a (projected) > 100 kpc scale. It is a known strong γ-ray emitter with a luminous flare reported previously. At redshift z=1.004, this is the most distant γ-NLS1 known to date. Copyright © 2019, The Authors. All rights reserved.

关键词： Galaxies

Which evolutionary status does the Blue Large-Amplitude Pulsators stay at?

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arXiv 2018年

作者： Wu, Tao Li, Yan Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China University of Chinese Academy of Sciences Beijing100049 China

Asteroseismology is a very useful tool for exploring the stellar interiors and evolution- ary status and for determining stellar fundamental parameters, such as stellar mass, radius, surface gravity, and the stellar mean density. In the present work, we use it to preliminarily analyze the 14 new-type pulsating stars: Blue Large-Amplitude Pulsators (BLAPs) which is observed by OGLE project, to roughly analyze their evolutionary status. We adopt the theory of single star evolution and artificially set the mass loss rate of M = -2 × 10-4Mo/year and mass loss beginning at the radius of R = 40 Ro on red giant branch to generate a series of theoretical models. Based on these theoretical models and the corresponding observations, we find that those BLAP stars are more likely to be the core helium burning stars. Most of them are in the middle and late phase of the helium burning. Copyright © 2018, The Authors. All rights reserved.

关键词： Gravitation

Fast inflow directly feeding black hole accretion disk in quasars

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arXiv 2019年

作者： Zhou, Hongyan Shi, Xiheng Yuan, Weimin Hao, Lei Chen, Xiangjun Ge, Jian Ji, Tuo Jiang, Peng Li, Ge Liu, Bifang Liu, Guilin Liu, Wenjuan Lu, Honglin Pan, Xiang Shen, Juntai Shu, Xinwen Sun, Luming Tian, Qiguo Wang, Huiyuan Wang, Tinggui Wu, Shengmiao Yang, Chenwei Zhang, Shaohua Zhong, Zhihao Antarctic Astronomy Research Division Key Laboratory for Polar Science of the State Oceanic Administration Polar Research Institute of China Shanghai China School of Astronomy and Space Sciences University of Science and Technology of China Hefei China Key Laboratory for Research in Galaxies and Cosmology of Chinese Academy of Sciences Department of Astronomy University of Science and Technology of China Hefei China National Astronomical Observatories of China Chinese Academy of Sciences Beijing China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing China Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai China Department of Astronomy University of Florida Bryant Space Science Center GainesvilleFL United States Yunnan Observatories Chinese Academy of Sciences Kunming China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming China Department of Physics Anhui Normal University Wuhu China

Quasars are high-luminosity active galactic nuclei believed to be powered by accretion of interstellar matter onto a super-massive black hole (SMBH) therein. Most of the observed energy is released in an accretion disk of inspiralling gas surrounding the SMBH. An enormous amount of fueling material, up to several tens solar masses per year, is expected to be transported inwards and consumed in the end. However, basic questions remain unanswered as to whether and how the accretion disks are supplied with external gas, since no disk-feeding inflow has hitherto been observed clearly. Here we report the discovery of highly redshifted broad absorption lines arising from neutral hydrogen and helium atoms in a small sample of quasars. Their absorption troughs show a broad range of Doppler velocities from zero extending continuously inward up to as high as ∼ 5, 000 km s−1, comparable to the free-fall speeds close to the SMBH and constraining the fastest in-falling gas to be within 104 gravitational radii. We thus see through streams of cold gas moving with a radially inward velocity component that spans an immense gradient—a result of gravitational acceleration by the central SMBH. Extensive photo-ionization modeling for the archetypical object SDSS J103516.20+142200.6 indicates the inflowing gas to be dense, thick and moderately ionized, with a characteristic distance to the SMBH of ∼ 1, 000 gravitational radii, possibly overlapping or close to the outer accretion disk. Our results present the first compelling evidence for the long-sought inflow directly feeding quasars’ accretion disks with external materials, likely originating from the dusty torus at a parsec scale. Our approach provides a new tool to probe the bulk of the so far elusive fueling inflows in quasars. Their studies may help address some of the fundamental questions concerning accretion physics, the onset and sustainment of quasar activity, and the SMBH growth at centers of most galaxies. Copyright © 2019,

关键词： Galaxies

Vertical structure of radiation-pressure-dominated thin disks: Link between vertical advection and convective stability

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arXiv 2017年

作者： Gong, Hong-Yu Gu, Wei-Min Department of Astronomy Xiamen University Xiamen Fujian361005 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

In the classic picture of standard thin accretion disks, the viscous heating is balanced by the radiative cooling through the diffusion process, and the radiation-pressure-dominated inner disk suffers convec-tive instability. However, recent simulations have shown that the vertical advection process owing to the magnetic buoyancy can make significant contribution to the energy transport. In addition, no convective instability has been found by comparing the simulation results with the local convective stability criterion. In this work, following the spirit of simulations, we revisit the vertical structure of radiation-pressure-dominated thin disks by including the vertical advection process. Our study indicates a link between the additional energy transport and the convectively stable property. Thus, the vertical advection not only has significant contribution to the energy transport, but also plays an important role to make the disk convectively stable. Our analyses may be helpful to understand the discrepancy between the classic theory and simulations on standard thin disks. Copyright © 2017, The Authors. All rights reserved.

关键词： Stability criteria

A new C-D-like diagram for SPB stars: The variations of period spacing as a signature of evolutionary status

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arXiv 2018年

作者： Wu, Tao Li, Yan Deng, Zhen-Min Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects 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 University of Chinese Academy of Sciences Beijing100049 China

The Slowly Pulsating B-type (SPB) stars are the upper main-sequence stars on the HR diagram. Their oscillations are high-order, low-degree g-mode and can be used to probe the structure of the radiative zone where is near the outer boundary of the convective core and constrain the chemical mixing in stellar interiors. In SPB stars, the period spacing periodically varies with periods. It has regarded as a signature of the chemical composition gradient beyond the convective core. Based on theoretical calculations, we find that the variation frequency of the period spacings (fδP) is related to the width of the μ-gradient region on the buoyancy radius (Λμ) with the relation of fδP∼ 0.5Λμ. This indicates that the variation frequency fδPis sensitive to the central hydrogen mass fraction XC(i.e., the evolutionary status). Finally, we find that the variation frequency fδPand the means of the period spacings 〈δP〉 can be used to construct a new C-D-like diagram (fδPvs. 〈δP〉) which can be used to roughly decide the stellar evolutionary stages and to approximately determine stellar mass for SPB stars. Copyright © 2018, The Authors. All rights reserved.

关键词： Stars

A new hyper-runaway star discovered from lamost and gaia: Ejected almost in the galactic rotation direction

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arXiv 2018年

作者： Li, Yin-Bi Luo, A-Li Zhao, Gang Lu, You-Jun Zhang, Xue-Sen Zhang, Fu-Peng Du, Bing Zuo, Fang Zhang, Lan Huang, Yang Xiang, Mao-Sheng Zhao, Jing-Kun Zhao, Yong-Heng Han, Zhan-Wen Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Technology Co. Ltd Beijing100102 China School of Physics and Astronomy Sun Yat-sen University Guangzhou510275 China South-Western Institute for Astronomy Research Yunnan University Kunming650500 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories Chinese Academy of Sciences Kunming650216 China

In this paper, we report the discovery of a new late-B type unbound hyper-runaway star (LAMOST-HVS4) from the LAMOST spectroscopic surveys. According to its atmospheric parameters, it is either a B-type main-sequence (MS) star or a blue horizontal branch (BHB) star. Its Galactocentric distance and velocity are 30.3 ± 1.6 kpc and 586±7 km s−1 if it is an MS star, and they are 13.2 ± 3.7 kpc and 590±7 km s−1 if a BHB star. We track its trajectories back, and find that the trajectories intersect with the Galactic disk and the Galactic center lies outside of the intersection region at the 3σ confidence level. We investigate a number of mechanisms that could be responsible for the ejection of the star, and find that it is probably ejected from the Galactic disk by supernova explosion or multiple-body interactions in dense young stellar clusters. Copyright © 2018, The Authors. All rights reserved.

关键词： Galaxies

Active galactic nuclei with ultra-fast outflows monitoring project: The broad-line region of MRK 79 as a disk wind

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arXiv 2019年

作者： Lu, Kai-Xing Bai, Jin-Ming Zhang, Zhi-Xiang Du, Pu Hu, Chen Kim, Minjin Wang, Jian-Min Ho, Luis C. Li, Yan-Rong Bian, Wei-Hao Yuan, Ye-Fei Xiao, Ming Feng, Hai-Cheng Wang, Jian-Guo Xu, Liang Ding, Xu Yu, Xiao-Guang Xin, Yu-Xin Ye, Kai Wang, Chuan-Jun Lun, Bao-Li Zhang, Ju-Jia Zhang, Xi-Liang Ji, Kai-Fan Fan, Yu-Feng Chang, Liang Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Department of Astronomy Xiamen University Xiamen Fujian361005 China Key Laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences 19B Yuquan Road Beijing100049 China Department of Astronomy and Atmospheric Sciences Kyungpook National University Daegu702-701 Korea Republic of Korea Astronomy and Space Science Institute Daejeon305-348 Korea Republic of Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Department of Astronomy School of Physics Peking University Beijing100871 China Physics Department Nanjing Normal University Nanjing210097 China Department of Astronomy University of Science and Technology of China Hefei230026 China

We developed a spectroscopic monitoring project to investigate the kinematics of the broad-line region (BLR) in active galactic nuclei (AGN) with ultra-fast outflows (UFOs). Mrk 79 is a radio-quiet AGN with UFOs and warm absorbers, had been monitored by three reverberation mapping (RM) campaigns, but its BLR kinematics is not understood yet. In this paper, we report the results from a new RM-campaign of Mrk 79, which was undertaken by Lijiang 2.4-m telescope. Mrk 79 is seeming to come out the faint state, the mean flux approximates a magnitude fainter than historical record. We successfully measured the lags of the broad emission lines including Hβ λ4861, Hγ λ4340, He II λ4686 and He I λ5876 with respect to the varying AGN continuum. Based on the broad Hβ λ4861 line, we measured black hole (BH) mass of M• = 5.13+1−1..5755×107M, estimated accretion rates of M• = (0.05 ± 0.02) LEdd c−2, indicating that Mrk 79 is a sub-Eddington accretor. We found that Mrk 79 deviates from the canonical Radius−Luminosity relationship. The marginal blueshift of the broad He II λ4686 line detected from rms spectrum indicates outflow of high-ionization gas. The velocity-resolved lag profiles of the broad Hγ λ4340, Hβ λ4861, and He I λ5876 lines show similar signatures that the largest lag occurs in the red wing of the lines then the lag decreases to both sides. These signatures should suggest that the BLR of Keplerian motion probably exists the outflow gas motion. All findings including UFOs, warm absorbers, and the kinematics of high- and low-ionization BLR, may provide an indirect evidence that the BLR of Mrk 79 probably originates from disk wind. Copyright © 2019, The Authors. All rights reserved.

关键词： Kinematics