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arXiv 2024年

作者： Jacobson-Galán, W.V. Dessart, L. Davis, K.W. Kilpatrick, C.D. Margutti, R. Foley, R.J. Chornock, R. Terreran, G. Hiramatsu, D. Newsome, M. Padilla Gonzalez, E. Pellegrino, C. Howell, D.A. Filippenko, A.V. Anderson, J.P. Angus, C.R. Auchettl, K. Bostroem, K.A. Brink, T.G. Cartier, R. Coulter, D.A. de Boer, T. Drout, M.R. Earl, N. Ertini, K. Farah, J.R. Farias, D. Gall, C. Gao, H. Gerlach, M.A. Guo, F. Haynie, A. Hosseinzadeh, G. Ibik, A.L. Jha, S.W. Jones, D.O. Langeroodi, D. LeBaron, N. Magnier, E.A. Piro, A.L. Raimundo, S.I. Rest, A. Rest, S. Michael Rich, R. Rojas-Bravo, C. Sears, H. Taggart, K. Villar, V.A. Wainscoat, R.J. Wang, X.-F. Wasserman, A.R. Yan, S. Yang, Y. Zhang, J. Zheng, W. Department of Astronomy University of California BerkeleyCA94720-3411 United States Institut d'Astrophysique de Paris CNRS-Sorbonne Université 98 bis boulevard Arago ParisF-75014 France Department of Astronomy and Astrophysics University of California Santa CruzCA95064 United States Northwestern University EvanstonIL60202 United States Department of Physics and Astronomy Northwestern University EvanstonIL60208 United States Department of Physics University of California BerkeleyCA94720-7300 United States Las Cumbres Observatory 6740 Cortona Dr. Suite 102 GoletaCA93117 United States Center for Astrophysics | Harvard & Smithsonian 60 Garden Street CambridgeMA02138-1516 United States The NSF AI Institute for Artificial Intelligence and Fundamental Interactions United States Department of Physics University of California Santa Barbara Santa BarbaraCA93111 United States Department of Astronomy University of Virginia CharlottesvilleVA22904 United States European Southern Observatory Alonso de Córdova 3107 Casilla 19 Santiago Chile Millennium Institute of Astrophysics MAS Nuncio Monsenor Sotero Sanz 100 Off. 104 Providencia Santiago Chile DARK Niels Bohr Institute University of Copenhagen Jagtvej 128 Copenhagen2200 Denmark Astrophysics Research Centre School of Mathematics and Physics Queen's University Belfast BelfastBT7 1NN United Kingdom School of Physics The University of Melbourne VIC3010 Australia Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721-0065 United States LSST-DA Catalyst Gemini Observatory NSF's National Optical-Infrared Astronomy Research Laboratory Casilla 603 La Serena Chile Space Telescope Science Institute BaltimoreMD21218 United States Institute for Astronomy University of Hawaii 2680 Woodlawn Drive HonoluluHI96822 United States David A. Dunlap Department of Astronomy and Astrophysics University of Toronto 50 St. George Street TorontoONM5S 3H4 Canada Department of As

We present ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early-time (δt 15 cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) of H i, He i/ii, C iv, and N iii/iv/v from the CSM persist on a characteristic timescale (tIIn) that marks a transition to a lower-density CSM and the emergence of Doppler-broadened features from the fast-moving SN ejecta. Our sample, the largest to date, consists of 39 SNe with early-time IIn-like features in addition to 35 "comparison" SNe with no evidence of early-time IIn-like features, all with ultraviolet observations. The total sample consists of 50 unpublished objects with a total of 474 previously unpublished spectra and 50 multiband light curves, collected primarily through the Young Supernova Experiment and Global Supernova Project collaborations. For all sample objects, we find a significant correlation between peak ultraviolet brightness and both tIIn and the rise time, as well as evidence for enhanced peak luminosities in SNe II with IIn-like features. We quantify mass-loss rates and CSM density for the sample through matching of peak multiband absolute magnitudes, rise times, tIIn and optical SN spectra with a grid of radiation hydrodynamics and non-local thermodynamic equilibrium (nLTE) radiative-transfer simulations. For our grid of models, all with the same underlying explosion, there is a trend between the duration of the electron-scattering broadened line profiles and inferred mass-loss rate: tIIn ≈ 3.8[M¤/(0.01 M☉ yr−1)] days. Copyright © 2024, The Authors. All rights reserved.

关键词： Supernovae

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VARIABILITY OF LOW-IONIZATION BROAD ABSORPTION LINE QUASARS BASED ON MULTI-EPOCH SPECTRA FROM THE SLOAN DIGITAL SKY SURVEY

arXiv

引用

arXiv 2019年

作者： Yi, W. Brandt, W.N. Hall, P.B. Vivek, M. Grier, C.J. Ak, N. Filiz Schneider, D.P. McGraw, S.M. Department of Astronomy & Astrophysics Pennsylvania State University 525 Davey Lab University ParkPA16802 United States Yunnan Observatories Kunming650216 China Department of Physics and Astronomy York University TorontoONM3J 1P3 Canada Department of Physics Pennsylvania State University University ParkPA16802 United States Institute for Gravitation and the Cosmos Pennsylvania State University University ParkPA16802 United States Steward Observatory University of Arizona 933 North Cherry Avenue TucsonAZ85721 United States Faculty of Sciences Department of Astronomy and Space Sciences Erciyes University Kayseri38039 Turkey Astronomy and Space Sciences Observatory and Research Center Erciyes University Kayseri38039 Turkey Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China

We present absorption variability results for 134 bona fide Mg ii broad absorption line (BAL) quasars at 0.46 . z . 2.3 covering days to ∼ 10 yr in the rest frame. We use multiple-epoch spectra from the Sloan Digital Sky Survey, which has delivered the largest such BAL-variability sample ever studied. Mg ii-BAL identifications and related measurements are compiled and presented in a catalog. We find a remarkable time-dependent asymmetry in EW variation from the sample, such that weakening troughs outnumber strengthening troughs, the first report of such a phenomenon in BAL variability. Our investigations of the sample further reveal that (i) the frequency of BAL variability is significantly lower (typically by a factor of 2) than that from high-ionization BALQSO samples;(ii) Mg ii BAL absorbers tend to have relatively high optical depths and small covering factors along our line of sight;(iii) there is no significant EW-variability correlation between Mg ii troughs at different velocities in the same quasar;and (iv) the EW-variability correlation between Mg ii and Al iii BALs is significantly stronger than that between Mg ii and C iv BALs at the same velocities. These observational results can be explained by a combined transverse-motion/ionization-change scenario, where transverse motions likely dominate the strengthening BALs while ionization changes and/or other mechanisms dominate the weakening BALs. Copyright © 2019, The Authors. All rights reserved.

关键词： Ionization

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Optical precursors to X-ray binary outbursts

arXiv

引用

arXiv 2019年

作者： Russell, D.M. Bramich, D.M. Lewis, F. AlMannaei, A. Al Qaissieh, T. Al Qasim, A. Al Yazeedi, A. Baglio, M.C. Bernardini, F. Elgalad, N. Gabuya, A. Lasota, J.P. Palado, A. Roche, P. Shivkumar, H. Udrescu, S. Zhang, G. New York University Abu Dhabi Abu Dhabi United Arab Emirates Faulkes Telescope Project School of Physics and Astronomy Cardiff University Cardiff United Kingdom Astrophysics Research Institute Liverpool John Moores University Liverpool United Kingdom Al Sadeem Observatory Abu Dhabi United Arab Emirates Mullard Space Science Laboratory University College London Dorking United Kingdom INAF–Osservatorio Astronomico di Brera Merate Italy INAF–Osservatorio Astronomico di Roma Roma Italy INAF–Osservatorio Astronomico di Capodimonte Napoli Italy Paris-Sorbonne University Abu Dhabi Abu Dhabi United Arab Emirates Institut d’Astrophysique de Paris CNRS et Sorbonne Université Paris France Nicolaus Copernicus Astronomical Center Polish Academy of Sciences Warsaw Poland Kunming China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming China Center for Astronomical Mega-Science CAS Beijing China

Disc instability models predict that for X-ray binaries in quiescence, there should be a brightening of the optical flux prior to an X-ray outburst. Tracking the X-ray variations of X-ray binaries in quiescence is generally not possible, so optical monitoring provides the best means to measure the mass accretion rate variability between outbursts, and to identify the beginning stages of new outbursts. With our regular Faulkes Telescope/Las Cumbres Observatory (LCO) monitoring we are routinely detecting the optical rise of new X-ray binary outbursts before they are detected by X-ray all-sky monitors. We present examples of detections of an optical rise in X-ray binaries prior to X-ray detection. We also present initial optical monitoring of the new black hole transient MAXI J1820+070 (ASASSN-18ey) with the Faulkes, LCO telescopes and Al Sadeem Observatory in Abu Dhabi, UAE. Finally, we introduce our new real-time data analysis pipeline, the "X-ray Binary New Early Warning System (XB-NEWS)" which aims to detect and announce new X-ray binary outbursts within a day of first optical detection. This will allow us to trigger X-ray and multi-wavelength campaigns during the very early stages of outbursts, to constrain the outburst triggering mechanism. Copyright © 2019, The Authors. All rights reserved.

关键词： Stars

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Binary interactions and multiple stellar populations in globular clusters

引用

Proceedings of the International Astronomical Union 2017年第S316期12卷 316-319页

作者： Dengkai Jiang Zhanwen Han Lifang Li Yunnan Observatories Chinese Academy of Sciences P.O. Box 110 Kunming Yunnan Province 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China email: dengkai@***

Globular clusters (GCs) have multiple stellar populations, which show star-to-star abundance variations and multiple sequences (or spreads) in the Hertzsprung-Russell diagrams. It is explained by multiple generations of star-formation in GCs. However, the observed evidence of ongoing star-formation was not found within any clusters. Here we present a binary interactions scenario for the formation of multiple stellar populations in GCs, where GC stars were born in a single burst of star formation, but some of them are members of binary systems. Binary interactions can produce peculiar stars, e.g. the merged stars and the accretor stars. They are more massive than normal single stars in the same evolutionary stage, and they are rapidly rotating stars at the moment of their formation. Rotationally induced mixing can cause the variations of their surface chemical composition. This results in the single-generation GCs showing abundance anomalies.

关键词： globular clusters: general binary: general stars: evolution stars: rotation

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A lower occurrence rate of bright X-ray flares in SN-GRBs than z < 1 GRBs: Evidence of energy partitions?

arXiv

引用

arXiv 2018年

作者： Mu, Hui-Jun Gu, Wei-Min Mao, Jirong Liu, Tong Hou, Shu-Jin Lin, Da-Bin Wang, Junfeng Fang, Taotao Liang, En-Wei Department of Astronomy Xiamen University Xiamen Fujian361005 China Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan Province650011 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 College of Physics and Electronic Engineering Nanyang Normal University Nanyang Henan473061 China Guangxi Key Laboratory for Relativistic Astrophysics Department of Physics Guangxi University Nanning530004 China

关键词： Supernovae

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GOTO065054+593624: a peculiar dwarf nova identified in real time via Kilonova Seekers

arXiv

引用

arXiv 2025年

作者： Killestein, T.L. Ramsay, G. Kennedy, M. Kelsey, L. Steeghs, D. Littlefair, S. Godson, B. Lyman, J. Pursiainen, M. Warwick, B. Krawczyk, C. Nuttall, L.K. Wickens, E. Alexandrov, S.D. da Silva, C.M. Leadbeater, R. Ackley, K. Dyer, M.J. Jiménez-Ibarra, F. Ulaczyk, K. Galloway, D.K. Dhillon, V.S. O’Brien, P. Noysena, K. Kotak, R. Breton, R.P. Pallé, E. Pollacco, D. Kumar, A. O’Neill, D. Butterley, T. Wilson, R. Mattila, S. Sahu, A. Starling, R. Wang, C.Y. Liu, Q. Li, A. Dai, Z. Feng, H. Yuan, W. Billington, R. Bull, A.G. Gaudenzi, S. Gonano, V. Krawczyk, H. Mazzucato, M.T. Pasqua, A. da Silva Campos, J.A. Torres-Guerrero, M. Antonov, N.N. Bean, S.J. Boeneker, E.T. Brincat, S.M. Darlington, G.S. Dubois, F. Hambsch, F.-J. Messier, D. Oksanen, A. Poyner, G. Romanov, F.D. Sharp, I.D. Tordai, T. Vanmunster, T. Wenzel, K. Department of Physics & Astronomy University of Turku Vesilinnantie 5 TurkuFI-20014 Finland Armagh Observatory & Planetarium College Hill ArmaghBT61 9DG United Kingdom School of Physics University College Cork Kane Building Cork Ireland Institute of Astronomy Kavli Institute for Cosmology University of Cambridge Madingley Road CambridgeCB3 0HA United Kingdom Department of Physics University of Warwick Gibbet Hill Road CoventryCV4 7AL United Kingdom Astrophysics Research Cluster School of Mathematical and Physical Sciences University of Sheffield SheffieldS3 7RH United Kingdom Institute of Cosmology and Gravitation University of Portsmouth PortsmouthPO1 3FX United Kingdom Kilonova Seekers c/o Zooniverse Department of Physics University of Oxford Denys Wilkinson Building Keble Road OxfordOX1 3RH United Kingdom Institute of Plant Physiology and Genetics Bulgarian Academy of Sciences Acad. G. Bontchev Str. Bl.23 Sofia1113 Bulgaria American Association of Variable Star Observers 185 Alewife Brook Parkway Suite 410 CambridgeMA02138 United States Variable Stars South Royal Astronomical Society of New Zealand P O Box 3181 Wellington New Zealand British Astronomical Association Variable Star Section Burlington House Piccadilly LondonW1J 0DU United Kingdom School of Physics & Astronomy Monash University ClaytonVIC3800 Australia Instituto de Astrofísica de Canarias Tenerife La LagunaE-38205 Spain School of Physics & Astronomy University of Leicester University Road LeicesterLE1 7RH United Kingdom National Astronomical Research Institute of Thailand 260 Moo 4 T. Donkaew A. Maerim Chiangmai50180 Thailand Jodrell Bank Centre for Astrophysics Department of Physics and Astronomy The University of Manchester ManchesterM13 9PL United Kingdom Department of Physics Royal Holloway - University of London Egham Hill EghamTW20 0EX United Kingdom Centre for Advanced Instrumentation University of Durham DurhamDH1 3LE United Kingdom School of Sci

Dwarf novae are a crucial astrophysical laboratory for probing the nature of accretion, binary mass transfer, and binary evolution – yet their diverse observational characteristics continue to challenge our theoretical understanding. We here present the discovery of, and subsequent observing campaign on GOTO065054+593624 (hereafter GOTO0650), a dwarf nova of the WZ Sge type, discovered in real-time by citizen scientists via the Kilonova Seekers citizen science project. An extensive dataset charts the photometric and spectroscopic evolution of this object, covering the first two months of its 2024 superoutburst. GOTO0650 shows a complete absence of visible emission lines during the high state, strong H and barely-detected He II emission, and high-amplitude echo outbursts with a rapidly decreasing timescale that together do not neatly fit in with our current view of cataclysmic variables. The comprehensive dataset presented here not only underscores the uniqueness of this dwarf nova and marks it as a candidate period bouncer, but also highlights the important contribution that citizen scientists can make to the study of Galactic transients. Copyright © 2025, The Authors. All rights reserved.

关键词： Stars

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On the origin of the hard X-Ray excess of high-synchrotron-peaked BL Lac object Mrk 421

arXiv

引用

arXiv 2017年

作者： Chen, Liang Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

For the first time, Kataoka & Stawarz reported a clear detection of a hard X-ray excess, above ≿20 keV, in the high-synchrotron-peaked BL Lac object Mrk 421. We find that this feature may not be produced by the low-energy part of the same electron population that produced the Fermi/LAT γ-ray. Because of that it is required that the power-law electron energy go down to γmin ≈ 19, which predicts a very strong radio emission (radio flux larger than the observed) even considering the synchrotron self-absorption effect. We investigate the possibility of this excess being produced from the spine/layer jet structure, which has been clearly detected in Mrk 421. We find that (1) similar to one-zone modeling, the spine emissions provide good modeling of the broadband spectral energy distribution, except for the hard X-ray excess;and (2) the hard X-ray excess can be well represented by the synchrotron photons (from the layer) being inverse Compton scattered by the spine electrons. Copyright © 2017, The Authors. All rights reserved.

关键词： Gamma rays

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A low-mass-ratio and deep contact binary as the progenitor of the merger V1309 Sco

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Research in Astronomy and Astrophysics 2016年第4期16卷 129-132页

作者： Li-Ying Zhu Er-Gang Zhao Xiao Zhou Yunnan Observatories Chinese Academy of SciencesKunming 650011China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China University of the Chinese Academy of Sciences Beijing 100049China

Nova Sco 2008 （=V1309 Sco） is an example of a V838 Mon type eruption rather than a typical classical nova. This enigmatic object was recently shown to have resulted from the merger of two stars in a contact binary. It is the first stellar merger that was identified to be undergoing a common envelope transient. To understand the properties of its binary progenitor, the pre-outburst light curves were analyzed by using the W-D method. The photometric solution of the 2002 light curve shows that it is a deep contact binary （f = 89.5（~40.5）%） with a mass ratio of 0.094. The asymmetry of the light curve is explained by the presence of a dark spot on the more massive component. The extremely high fill-out factor suggests that the merging of the contact binary is driven by dynamical mass loss from the outer Lagrange point. However, the analysis of the 2004 light curve indicates that no solutions were obtained even at an extremely low mass ratio of q = 0.03. This suggests that the common convective envelope of the binary system disappeared and the secondary component spiraled into the envelope of the primary in 2004. Finally, the ejection of the envelope of the primary produced the outburst.

关键词： stars： binaries： close -- stars： binaries： eclipsing -- stars： individuals （V1309 Sco） -- stars：evolution -- stars： mass-loss

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CENTRAL ENGINE-POWERED BRIGHT X-RAY FLARES IN SHORT GAMMA-RAY BURSTS: A HINT OF BLACK HOLE-NEUTRON STAR MERGER?

arXiv

引用

arXiv 2018年

作者： Mu, Hui-Jun Gu, Wei-Min Mao, Jirong Hou, Shu-Jin Lin, Da-Bin Liu, Tong Department of Astronomy Xiamen University XiamenFujian361005 China Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan Province650011 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 College of Physics and Electronic Engineering Nanyang Normal University Nanyang Henan473061 China Guangxi Key Laboratory for Relativistic Astrophysics Department of Physics Guangxi University Nanning530004 China

Short gamma-ray bursts may originate from the merger of double neutron stars (NS) or that of a black hole (BH) and an NS. We propose that the bright X-ray flare related to the central engine reactivity may hint a BH-NS merger, since such a merger can provide more fall-back materials and therefore a more massive accretion disk than the NS-NS merger. Based on the observed 49 short bursts with Swift/X-ray Telescope follow-up observations, we find that three bursts have bright X-ray flares, among which three flares from two bursts are probably related to the central engine reactivity. We argue that these two bursts may originate from the BH-NS merger rather than the NS-NS merger. Our suggested link between the central engine-powered bright X-ray flare and the BH-NS merger event can be checked by the future gravitational wave detections from advanced LIGO and Virgo. keywords: accretion, accretion disks — gamma-ray burst: general — X-rays: general Copyright © 2018, The Authors. All rights reserved.

关键词： Stars

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Testing relativistic boost as the cause of gamma-ray quasi-periodic oscillation in a blazar

arXiv

引用

arXiv 2018年

作者： Yan, Dahai Zhou, Jianeng Zhang, Pengfei Zhu, Qianqian Wang, Jiancheng Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatory Chinese Academy of Sciences Kunming650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing210008 China Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 China Department of General Studies Nanchang Institute of Science & Technology Nanchang330108 China

The mechanism for producing gamma-ray quasi-periodic oscillation (QPO) in blazar is unknown. One possibility is the geometric model, in which without the need for intrinsic quasi-periodic variation, the relativistic Doppler factor changes periodically, resulting in observed gamma-ray QPO. We propose a method to test this geometric model. We analyze the Fermi-LAT data of PG 1553+113 spanning from 2008 August until 2018 February. According to 29 four-month average spectral energy distributions (SEDs) in the energy range of 0.1-300 GeV, we split the Fermi-LAT energy range into three bands: 0.1-1 GeV, 1-10 GeV, and 10-300 GeV. The spectrum in each energy range can be successfully fitted by a power-law. The light curves and photon indices in the three energy ranges are obtained. Then, light curves in three narrow energy ranges, i.e., 0.2-0.5 GeV, 2-5 GeV and 20- 40 GeV, are constructed, and the relative variability amplitudes in the three narrow energy ranges are calculated. A discrete- correlation analysis is performed for the light curves. Our results indicate that (i) the light curves in the different energy ranges follow the same pattern showed in the light curve above 0.1 GeV;(ii) the three groups of photon indices in the energy ranges of 0.1-1 GeV, 1-10 GeV, and 10-300 GeV keep nearly constant;(iii) the ratio between relative variability amplitudes in different narrow energy ranges are equal (within their errors) to the prediction by the Doppler e ect. Our results support the scenario of the relativistic boost producing the gamma-ray QPO for PG 1553+113. Copyright © 2018, The Authors. All rights reserved.

关键词： Germanium alloys

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