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A gamma-ray periodic modulation in globular cluster 47 tucanae

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arXiv 2018年

作者： Zhang, Peng-Fei Zhou, Jia-Neng Yan, Da-Hai Yan, Jing-Zhi Fan, Yi-Zhong Zhang, Li Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing210034 China Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 China Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Yunnan Observatory Chinese Academy of Sciences Kunming650011 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 Kunming650011 China School of Astronomy and Space Science University of Science and Technology of China Hefei Anhui230026 China

The Globular Cluster 47 Tucanae was firstly detected in gamma-rays by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope, and the gamma-ray emission has been widely attributed to the millisecond pulsars. In this work, we analyze the Fermi-LAT pass 8 data ranging from 2008 August to 2017 May and report the detection of a modulation with a period of 18:416 ± 0:008 hours at a significance level of ∼ 4:8σ. This is the first time to detect a significant modulation with a period much longer than that of millisecond pulsars in gamma-rays from Globular Clusters. The periodic modulation signal displays in the Swift-BAT data as well. The phase-folded Chandra X-ray light curve of a point source may have provided an additional clue. These facts indicate the detection of the first young pulsar binary in gamma-rays in Globular Clusters. Copyright © 2018, The Authors. All rights reserved.

关键词： Gamma rays

Massive stars, successes and challenges

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arXiv 2017年

作者： Meynet, Georges Maeder, André Georgy, Cyril Ekström, Sylvia Eggenberger, Patrick Barblan, Fabio Song, Han Feng Department of Astronomy University of Geneva Switzerland College of Science Guizhou University GuiyangGuizhou Province550025 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

We give a brief overview of where we stand with respect to some old and new questions bearing on how massive stars evolve and end their lifetime. We focus on the following key points that are further discussed by other contributions during this conference: convection, mass losses, rotation, magnetic field and multiplicity. For purpose of clarity, each of these processes are discussed on its own but we have to keep in mind that they are all interacting between them offering a large variety of outputs, some of them still to be discovered. Copyright © 2017, The Authors. All rights reserved.

关键词： Magnetic fields

Observations of a fast-expanding and uv-bright type ia supernova SN 2013gs

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arXiv 2019年

作者： Zhang, Tianmeng Wang, Xiaofeng Zhao, Xulin Xu, Dong Reguitti, Andrea Zhang, Jujia Pastorello, Andrea Tomasella, Lina Ochner, Paolo Tartaglia, Leonardo Benetti, Stefano Turatto, Massimo Harutyunyan, Avet Elias-Rosa, Nancy Huang, Fang Zhang, Kaicheng Chen, Juncheng Jiang, Zhaoji Ma, Jun Nie, Jundan Peng, Xiyan Zhou, Xu Zhou, Zhimin Zou, Hu Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China School of Astronomy and Space Science University of Chinese Academy of Sciences Tsinghua University Beijing100084 China School of Science Tianjin University of Technology Tianjin300384 China National Astronomical Observatories Chinese Academy of Sciences Beijing100012 China Dipartimento di Fisica e Astronomia G. Galilei Universita’ di Padova Vicolo dell’Osservaotio 3 Padova35122 Italy 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 20A Datun Road Chaoyang District Beijing100012 China INAF-Osservatorio Astronomico di Padova Vicolo dell’Osservatorio 5 Padova35122 Italy Department of Astronomy Stockholm University StockholmSE 10691 Sweden INAF-Fundacion Galileo Galilei Rambla Jose Ana Fernandez Perez 7 Brena BajaE-38712 Spain Department of Astronomy School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China

In this paper, we present extensive optical and ultraviolet (UV) observations of the type Ia supernova (SN Ia) 2013gs discovered during the Tsinghua-NAOC Transient Survey. The photometric observations in the optical show that the light curves of SN 2013gs is similar to that of normal SNe Ia, with an absolute peak magnitude of MB = −19.25 ± 0.15 mag and a post-maximum decline rate ∆m15(B) = 1.00 ± 0.05 mag. Gehrels Swift UVOT observations indicate that SN 2013gs shows unusually strong UV emission (especially in the uvw1 band) at around the maximum light (Muvw1 ∼ −18.9 mag). The SN is characterized by relatively weak Fe ii iii absorptions at ∼ 5000Å in the early spectra and a larger expansion velocity (vSi ∼ 13,000 km s−1 around the maximum light) than the normal-velocity SNe Ia. We discuss the relation between the uvw1−v color and some observables, including Si ii velocity, line strength of Si ii λ6355, Fe ii/iii lines and ∆m15(B). Compared to other fast-expanding SNe Ia, SN 2013gs exhibits Si and Fe absorption lines with similar strength and bluer uvw1 − v color. We briefly discussed the origin of the observed UV dispersion of SNe Ia. Copyright © 2019, The Authors. All rights reserved.

关键词： Supernovae

The double-degenerate model for the progenitors of type Ia supernovae

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arXiv 2017年

作者： Liu, D. Wang, B. Han, Z. Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories CAS Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Center for Astronomical Mega-Science CAS Beijing100012 China

The double-degenerate (DD) model, involving the merging of massive double carbon-oxygen white dwarfs (CO WDs) driven by gravitational wave radia- tion, is one of the classical pathways for the formation of type Ia supernovae (SNe Ia). Recently, it has been proposed that the WD+He subgiant channel has a significant contribution to the production of massive double WDs, in which the primary WD accumulates mass by accreting He-rich matter from a He subgiant. We evolved about 1800 CO WD+He star systems and ob- tained a large and dense grid for producing SNe Ia through the DD model. We then performed a series of binary population synthesis simulations for the DD model, in which the WD+He subgiant channel is calculated by interpo- lations in this grid. According to our standard model, the Galactic birthrate of SNe Ia is about 2.4 × 10-3yr-1for the WD+He subgiant channel of the DD model;the total birthrate is about 3.7×10-3 yr-1for all channels, repro- ducing that of observations. Previous theoretical models still have deficit with the observed SNe Ia with delay times 8Gyr. After considering the WD+He subgiant channel, we found that the delay time distributions is comparable with the observed results. Additionally, some recent studies pro- posed that the violent WD mergers are more likely to produce SNe Ia based on the DD model. We estimated that the violent mergers through the DD model may only contribute to about 16% of all SNe Ia. Copyright © 2017, The Authors. All rights reserved.

关键词： White dwarfs

Chromospheric activity on the late-type star V1355 Ori using Lijiang 1.8-m and 2.4-m telescopes

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Research in Astronomy and Astrophysics 2016年第10期16卷 27-34页

作者： Qing-Feng Pi Li-Yun Zhang Liang Chang Xian-Ming Han Hong-Peng Lu Xi-Liang Zhang Dai-Mei Wang College of Physics/Department of Physics and Astronomy Guizhou University Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Mingde College Guizhou University Yunnan Observatories Chinese Academy of Sciences Dept.of Physics and Astronomy Butler University

We obtained new high-resolution spectra using the Lijiang 1.8-m and 2.4-m telescopes to inves- tigate the chromospheric activities of V1355 Ori as indicated in the behaviors of Ca n H＆K, Hγ HT, H/3, Na1 D1, D2, Ha and Ca II infrared triplet （IRT） lines. The observed spectra show obvious emissions above the continuum in Ca II H＆K lines, absorptions in the Hδ, Hγ, H/3 and NaI D1, D2 lines, variable behavior （filled-in absorption, partial emission with a core absorption component or emission above the continuum） in the Ha line, and weak self-reversal emissions in the strong filled-in absorptions of the Ca II IRT lines. We used a spectral subtraction technique to analyze our data. The results show no excess emission in the H6 and H7 lines, very weak excess emissions in the Na I D1, D2 lines, excess emission in the H/3 line, clear excess emission in the Ha line, and excess emissions in the Ca II IRT lines. The value of the ratio of EWs542/EWsa9s is in the range 0.9 to 1.7, which implies that chromospheric activity might have been caused by plage events. The value of the ratio EHδ/EHβ is above 3, indicating that the Balmer lines would arise from prominence-like material. We also found time variations in light curves associated with equiva- lent widths of chromospheric activity lines in the Na I D1, phenomena can be explained by plage events, which are activity indicators. D2, Ca II IRT and Ha lines in particular. These consistent with the behavior of chromospheric

关键词： stars： chromosphere- stars： activity -- stars： individual （V1355 Ori）

Comprehensive models of novae at metallicity Z = 0.02 and Z = 10−4

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arXiv 2019年

作者： Chen, Hai-Liang Woods, T.E. Yungelson, L.R. Piersanti, Luciano Gilfanov, M. Han, Zhanwen Yunnan Observatories Chinese Academy of Sciences Kunming650011 China Max Planck Institute for Astrophysics Karl-Schwarzschild-Str. 1 Garching b. München85741 Germany Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Science Beijing100012 China Institute of Gravitational Wave Astronomy School of Physics and Astronomy University of Birmingham Edgbaston BirminghamB15 2TT United Kingdom Institute of Astronomy RAS 48 Pyatnitskaya Str. Moscow119017 Russia Space Research Institute of Russian Academy of Sciences Profsoyuznaya 84/32 Moscow117997 Russia INAF – Osservatorio Astronomico d’Abruzzo via Mentore Maggini snc TeramoI-64100 Italy INFN – Sezione di Perugia via Pascoli Perugia Italy Kazan Federal University Kremlevskaya str. 18 Kazan420008 Russia

Novae are the observational manifestations of thermonuclear runaways on the surface of accreting white dwarfs (WDs). Although novae are an ubiquitous phenomenon, their properties at low metallicity are not well understood. Using the publicly-available stellar evolution code Modules for Experiments in Stellar Astrophysics (MESA), we model the evolution of accreting carbon-oxygen WDs and consider models which accrete matter with metallicity Z=0.02 or 10−4. We consider both models without mixing and with matter enriched by CO-elements assuming that mixing occurs in the process of accretion (with mixing fraction 0.25). We present and contrast ignition mass, ejected mass, recurrence period and maximum luminosity of novae for different WD masses and accretion rates for these metallicities and mixing cases. We find that models with Z = 0.02 have ignition masses and recurrence periods smaller than models with low Z, while the ejected mass and maximum luminosity are larger. Retention efficiency during novae outbursts decreases with increasing metallicity. In our implementation, inclusion of mixing at the H/He interface reduces accreted mass, ejected mass and recurrence period as compared to the no-mixing case, while the maximum luminosity becomes larger. Retention efficiency is significantly reduced, becoming negative in most of our models. For ease of use, we provide a tabular summary of our results. Copyright © 2019, The Authors. All rights reserved.

关键词： Astrophysics

A uniformly selected sample of low-mass black holes in seyfert 1 galaxies. II. the sdss dr7 sample

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arXiv 2018年

作者： Liu, He-Yang Yuan, Weimin Dong, Xiao-Bo Zhou, Hongyan Liu, Wen-Juan Key Laboratory of Space Astronomy and Technology National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China School of Astronomy and Space Sciences University of Chinese Academy of Sciences 19A Yuquan Road Beijing100049 China Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan650011 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming Yunnan650011 China Polar Research Institute of China 451 Jinqiao Road Shanghai200136 China University of Sciences and Technology of China Chinese Academy of Sciences Hefei Anhui230026 China

A new sample of 204 low-mass black holes (LMBHs) in active galactic nuclei (AGNs) is presented with black hole masses in the range of (1-20) × 105 Mo. The AGNs are selected from a systematic search among galaxies in the seventh Data Release (DR 7) of the Sloan Digital Sky Survey (SDSS), by careful analyses of their optical spectra and precise measurement of spectral parameters. Combining them with our previous sample selected from the SDSS DR 4 makes it the largest LMBH sample so far, totaling over 500 objects. Some of the statistical properties of the combined LMBH AGN sample are briefly discussed, in the context of exploring the low-mass end of the AGN population. Their X-ray luminosities follow the extension of the previously known correlation with the [O III] luminosity. The effective optical-to-X-ray spectral indices αOX, albeit with a large scatter, are broadly consistent with the extension of the relation with the near-UV luminosity L2500Å. Interestingly, a correlation of αOX with black hole mass is also found in the sense that αOX is statistically flatter (stronger X-ray relative to optical) for lower black hole mass. Only 26 objects, mostly radio loud, were detected in radio at 20 cm in the FIRST survey, giving a radio loud fraction of 4%. The host galaxies of LMBHs have stellar masses in the range of 108.8-1012.4 Mo and optical colors typical of Sbc spirals. They are dominated by young stellar populations which seem to have undergone a continuous star formation history. Copyright © 2018, The Authors. All rights reserved.

关键词： Stars

SEARCH FOR EXTENDED GEV SOURCES IN THE INNER GALACTIC PLANE

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arXiv 2024年

作者： Abdollahi, S. Acero, F. Acharyya, A. Adelfio, A. Ajello, M. Baldini, L. Ballet, J. Bartolini, C. Gonzalez, J. Becerra Bellazzini, R. Bissaldi, E. Bonino, R. Bruel, P. Cameron, R.A. Caraveo, P.A. Castro, D. Cavazzuti, E. Cheung, C.C. Cibrario, N. Ciprini, S. Cozzolongo, G. Orestano, P. Cristarella Cuoco, A. Cutini, S. D’Ammando, F. Di Lalla, N. Dinesh, A. Di Venere, L. Domínguez, A. Fiori, A. Funk, S. Fusco, P. Gargano, F. Gasbarra, C. Gasparrini, D. Germani, S. Giacchino, F. Giglietto, N. Giliberti, M. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guillemot, L. Guiriec, S. Gupta, R. Hashizume, M. Hays, E. Hewitt, J.W. Horan, D. Hou, X. Kayanoki, T. Kuss, M. Laviron, A. Lemoine-Goumard, M. Liguori, A. Li, J. Liodakis, I. Loizzo, P. Longo, F. Loparco, F. Lorusso, L. Lovellette, M.N. Lubrano, P. Maldera, S. Malyshev, D. Martí-Devesa, G. Martin, P. Mazziotta, M.N. Mereu, I. Michelson, P.F. Mirabal, N. Mitthumsiri, W. Mizuno, T. Monti-Guarnieri, P. Monzani, M.E. Morselli, A. Moskalenko, I.V. Negro, M. Omodei, N. Orienti, M. Orlando, E. Paneque, D. Panzarini, G. Persic, M. Pesce-Rollins, M. Pillera, R. Porter, T.A. Rainò, S. Rando, R. Razzano, M. Reimer, A. Reimer, O. Bernal, M. Rocamora Sánchez-Conde, M. Parkinson, P.M. Saz Serini, D. Sgrò, C. Siskind, E.J. Smith, D.A. Spandre, G. Spinelli, P. Strong, A.W. Suson, D.J. Tajima, H. Thayer, J.B. Torres, D.F. Valverde, J. Wadiasingh, Z. Wood, K. Zaharijas, G. IRAP Université de Toulouse CNRS UPS CNES ToulouseF-31028 France AIM CEA CNRS Université Paris-Saclay Université de Paris Gif-sur-YvetteF-91191 France Center for Cosmology and Particle Physics Phenomenology University of Southern Denmark Campusvej 55 Odense MDK-5230 Denmark Istituto Nazionale di Fisica Nucleare Sezione di Perugia PerugiaI-06123 Italy Department of Physics and Astronomy Clemson University Kinard Lab of Physics ClemsonSC29634-0978 United States Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Université Paris-Saclay Université Paris Cité CEA CNRS AIM Gif-sur-YvetteF-91191 Cedex France Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy Università degli studi di Trento via Calepina 14 Trento38122 Italy Instituto de Astrofísica de Canarias Universidad de La Laguna Dpto. Astrofísica Tenerife La Laguna38200 Spain Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Dipartimento di Fisica "M. Merlin" dell’Università e del Politecnico di Bari via Amendola 173 BariI-70126 Italy Istituto Nazionale di Fisica Nucleare Sezione di Torino TorinoI-10125 Italy Dipartimento di Fisica Università degli Studi di Torino TorinoI-10125 Italy Laboratoire Leprince-Ringuet CNRS IN2P3 École polytechnique Institut Polytechnique de Paris Palaiseau91120 France W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano via E. Bassini 15 MilanoI-20133 Italy Harvard-Smithsonian Center for Astrophysics CambridgeMA02138 United States Astrophysics Science Division NASA Goddard Space Flight Center GreenbeltMD20771 United States Italian Space Agency Via del Politecnico snc Roma00133 Italy Space Science Division Naval Research Laboratory Washin

The recent detection of extended γ-ray emission around middle-aged pulsars is interpreted as inverse-Compton scattering of ambient photons by electron-positron pairs escaping the pulsar wind nebula, which are confined near the system by unclear mechanisms. This emerging population of γ-ray sources was first discovered at TeV energies and remains underexplored in the GeV range. To address this, we conducted a systematic search for extended sources along the Galactic plane using 14 years of Fermi-LAT data above 10 GeV, aiming to identify a number of pulsar halo candidates and extend our view to lower energies. The search covered the inner Galactic plane (|l| ≤ 100◦, |b| ≤ 1◦) and the positions of known TeV sources and bright pulsars, yielding broader astrophysical interest. We found 40 such sources, forming the Second Fermi Galactic Extended Sources Catalog (2FGES), most with 68% containment radii smaller than 1.0◦ and relatively hard spectra with photon indices below 2.5. We assessed detection robustness using field-specific alternative interstellar emission models and by inspecting significance maps. Noting 13 sources previously known as extended in the 4FGL-DR3 catalog and five dubious sources from complex regions, we report 22 newly detected extended sources above 10 GeV. Of these, 13 coincide with H.E.S.S., HAWC, or LHAASO sources;six coincide with bright pulsars (including four also coincident with TeV sources);six are associated with 4FGL point sources only;and one has no association in the scanned catalogs. Notably, six to eight sources may be related to pulsars as classical pulsar wind nebulae or pulsar halos. © 2024, CC BY.

关键词： Gamma rays

Interstellar Scintillation observations for PSR B0355+54

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arXiv 2018年

作者： Xu, Y.H. Lee, K.J. Hao, L.F. Wang, H.G. Liu, Z.Y. Yue, Y.L. Yuan, J.P. Li, Z.X. Wang, M. Dong, J. Tan, J.J. Chen, W. Bai, J.M. Yunnan Astronomical Observatory Chinese Academy of Sciences Kunming650011 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China University of Chinese Academy of Sciences Beijing100049 China Center for Astrophysics Guangzhou University Guangzhou510006 China Key Laboratory for Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China Xinjiang Astronomical Observatory Chinese Academy of Sciences 150 Science 1-street Urumqi Xinjiang830011 China National Astronomical Observatories Chinese Academy of Sciences Beijing China

In this paper, we report our investigation of pulsar scintillation phenomena by monitor- ing PSR B0355+54 at 2.25 GHz for three successive months using Kunming 40-m radio telescope. We have measured the dynamic spectrum, the two-dimensional correlation function, and the secondary spectrum. In those observations with high signal-to-noise ratio (S/N ≥ 100), we have detected the scintillation arcs, which are rarely observable using such a small telescope. The sub-microsecond scale width of the scintillation arc indicates that the transverse scale of structures on scattering screen is as compact as AU size. Our monitoring has also shown that both the scintillation bandwidth, timescale, and arc curvature of PSR B0355+54 were varying temporally. The plausi- ble explanation would need to invoke multiple-scattering-screen or multiple-scattering- structure scenario that different screens or ray paths dominate the scintillation process at different epochs. Copyright © 2018, The Authors. All rights reserved.

关键词： Scintillation