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Ready for O4 II: GRANDMA Observations of Swift GRBs during eight-weeks of Spring 2022

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arXiv 2023年

作者： Tosta e Melo, I. Ducoin, J.-G. Vidadi, Z. Andrade, C. Rupchandani, V. Agayeva, S. Abdelhadi, J. Abe, L. Aguerre-Chariol, O. Aivazyan, V. Alishov, S. Antier, S. Bai, J.-M. Baransky, A. Bednarz, S. Bendjoya, Ph. Benkhaldoun, Z. Beradze, S. Bizouard, M.A. Bhardwaj, U. Blazek, M. Boër, M. Broens, E. Burkhonov, O. Christensen, N. Cooke, J. Corradi, W. Coughlin, M.W. Culino, T. Daigne, F. Dornic, D. Duverne, P.-A. Ehgamberdiev, S. Eymar, L. Fouad, A. Freeberg, M. Gendre, B. Guo, F. Gokuldass, P. Guessoum, N. Gurbanov, E. Hainich, R. Hasanov, E. Hello, P. Inasaridze, R. Iskandar, A. Ismailov, N. Janati, A. Jegou du Laz, T. Kann, D.A. Karpov, S. Kiendrebeogo, R.W. Klotz, A. Kneip, R. Kochiashvili, N. Kaeouach, A. Kruiswijk, K. Lamoureux, M. Leroy, N. Lin, W.L. Mao, J. Marchais, D. Mašek, M. Midavaine, T. Moller, A. Morris, D. Natsvlishvili, R. Navarete, F. Nicuesa Guelbenzu, A. Noonan, K. Noysena, K. Oksanen, A. Orange, N.B. Pellouin, C. Peloton, J. Peng, H.W. Pilloix, M. Popowicz, A. Pradier, T. Pyshna, O. Raaijmakers, G. Rajabov, Y. Rau, A. Rinner, C. Rivet, J.-P. Ryh, A.S. Sabil, M. Sadibekova, T. Sasaki, N. Serrau, M. Simon, A. Shokry, Ahmed Smith, K. Sokoliuk, O. Song, X. Takey, A. Thierry, P. Tillayev, Y. Turpin, D. de Ugarte Postigo, A. Vasylenko, V. Vernet, D. Wang, L. Vachier, F. Vignes, J.P. Wang, X.F. Zeng, X. Zhang, J. Zhu, Y. Department of Physics and Astronomy University of Catania Catania95125 Italy Sorbonne Université CNRS UMR 7095 Institut d'Astrophysique de Paris 98 bis bd Arago Paris75014 France N.Tusi Shamakhy Astrophysical Observatory Azerbaijan National Academy of Sciences settl.Y. Mammadaliyev ShamakhyAZ 5626 Azerbaijan School of Physics and Astronomy University of Minnesota MinneapolisMN55455 United States Brown University RI ProvidenceRI02912 United States Oukaimeden Observatory High Energy Physics and Astrophysics Laboratory FSSM Cadi Ayyad University Av. Prince My Abdellah MarrakeshBP 2390 Morocco Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Laboratoire J.-L. Lagrange Boulevard de l'Observatoire Nice06304 France 14 rue Saint-Hubert Orry-la-VilleF-60560 France E. Kharadze Georgian National Astrophysical Observatory Mt.Kanobili Abastumani Adigeni0301 Georgia Samtskhe-Javakheti State University Rustaveli Str. 113 Akhaltsikhe0080 Georgia N.Tusi Shamakhy astrophysical Observatory Azerbaijan National Academy of Sciences settl.Mamedaliyev ShamakhyAZ 5626 Azerbaijan Université Côte d'Azur Observatoire de la Côte d'Azur CNRS Artemis Boulevard de l'Observatoire Nice06304 France Astronomical Observatory Taras Shevshenko National University of Kyiv Observatorna str. 3 Kyiv04053 Ukraine Silesian University of Technology Faculty of Automatic Control Electronics and Computer Science Akademicka 16 Gliwice44-100 Poland GRAPPA Anton Pannekoek Institute for Astronomy Institute of High-Energy Physics University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands FZU - Institute of Physics The Czech Academy of Sciences Na Slovance 1999/2 PrahaCZ-182 21 Czech Republic Vereniging or Sterrenkunde Balen-Neetlaan 18A Mol2400 Belgium Ulugh Beg Astronomical Institute Uzbekistan Academy of Sciences Astronomy str. 33 Tashkent100052 Uzbekistan Centre for Astrophysics and Supercomputing Swinburne University of Technology HawthornVIC3122

Aims. We present a campaign designed to train the GRANDMA network and its infrastructure to follow up on transient alerts and detect their early afterglows. In preparation for O4 II campaign, we focused on GRB alerts as they are expected to be an electromagnetic counterpart of gravitational-wave events. Our goal was to improve our response to the alerts and start prompt observations as soon as possible to better prepare the GRANDMA network for the fourth observational run of LIGO-Virgo-Kagra (which started at the end of May 2023), and future missions such as SM. Methods. To receive, manage and send out observational plans to our partner telescopes we set up dedicated infrastructure and a rota of follow-up adcates were organized to guarantee round-the-clock assistance to our telescope teams. To ensure a great number of observations, we focused on Swift GRBs whose localization errors were generally smaller than the GRANDMA telescopes' field of view. This allowed us to bypass the transient identification process and focus on the reaction time and efficiency of the network. Results. During'Ready for O4 II', 11 Swift/INTEGRAL GRB triggers were selected, nine fields had been observed, and three afterglows were detected (GRB 220403B, GRB 220427A, GRB 220514A), with 17 GRANDMA telescopes and 17 amateur astronomers from the citizen science project Kilonova-Catcher. Here we highlight the GRB 220427A analysis where our long-term follow-up of the host galaxy allowed us to obtain a photometric redshift of z = 0.82 ± 0.09, its lightcurve elution, fit the decay slope of the afterglows, and study the properties of the host galaxy. Conclusions. During this 8-week-long GRB follow-up campaign, we successfully fulfilled our goal of training telescope teams for O4 and the improvement of the associated technical toolkits. For seven of the GRB alerts, our network was able to start the first observations less than one hour after the GRB trigger time. We also characterized the network effic

关键词： Telescopes

Light curve inversion of asteroid(585)Bilkis with Lommel-Seeliger ellipsoid method

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Research in Astronomy and Astrophysics 2016年第12期16卷 19-26页

作者： Ao Wang Xiao-Bin Wang Karri Muinonen Xianming L.Han Yi-Bo Wang Yunnan Observatories Chinese Academy of SciencesKunming 650011China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650011China University of Chinese Academy of Sciences Beijing 100049China Department of Physics University of HelsinkiGustaf Hallstromin katu 2aEO.Box 64FI-00014 U.HelsinkiFinland Finnish Geospatial Research Institute Geodeetinrinne 2FI-02430 MasalaFinland Department of Physics and Astronomy Butler UniversityIndianapolisIN 46208USA

The basic physical parameters of asteroids, such as spin parameters, shape and scattering parameters, can provide us with information on the formation and evolution of both the asteroids themselves and the entire solar system. In a majority of asteroids, the disk-integrated photometry measurement constitutes the primary source of the above knowledge. In the present paper, newly observed photometric data and existing data on（585） Bilkis are analyzed based on a Lommel-Seeliger ellipsoid model. With a Markov chain Monte Carlo（MCMC） method, we have determined the spin parameters（period, pole orientation）and shape（b/a, c/a） of（585） Bilkis and their uncertainties. As a result, we obtained a rotational period of 8.5738209 h with an uncertainty of 9×10^-7h, and derived a pole of（136.46°, 29.0°） in the ecliptic frame of J2000.0 with uncertainties of 0.67°and 1.1°in longitude and latitude respectively. We also derived triaxial ratios b/a and c/a of（585） Bilkis as 0.736 and 0.70 with uncertainties of 0.003 and 0.03 respectively.

关键词： asteroids -- photometric observation -- spin parameter -- shape -- MCMC method

Panchromatic evolution of three luminous red novae: Forbidden hugs in pandemic times - IV

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arXiv 2022年

作者： Pastorello, A. Valerin, G. Fraser, M. Reguitti, A. Elias-Rosa, N. Filippenko, A.V. Rojas-Bravo, C. Tartaglia, L. Reynolds, T.M. Valenti, S. Andrews, J.E. Ashall, C. Bostroem, K.A. Brink, T.G. Burke, J. Cai, Y.-Z. Cappellaro, E. Coulter, D.A. Dastidar, R. Davis, K.W. Dimitriadis, G. Fiore, A. Foley, R.J. Fugazza, D. Galbany, L. Gangopadhyay, A. Geier, S. Gutiérrez, C.P. Haislip, J. Hiramatsu, D. Holmbo, S. Howell, D.A. Hsiao, E.Y. Hung, T. Jha, S.W. Kankare, E. Karamehmetoglu, E. Kilpatrick, C.D. Kotak, R. Kouprianov, V. Kravtsov, T. Kumar, S. Li, Z.-T. Lundquist, M.J. Lundqvist, P. Matilainen, K. Mazzali, P.A. McCully, C. Misra, K. Morales-Garoffolo, A. Moran, S. Morrell, N. Newsome, M. Gonzalez, E. Padilla Pan, Y.-C. Pellegrino, C. Phillips, M.M. Pignata, G. Piro, A.L. Reichart, D.E. Rest, A. Salmaso, I. Sand, D.J. Siebert, M.R. Smartt, S.J. Smith, K.W. Srivastav, S. Stritzinger, M.D. Taggart, K. Tinyanont, S. Yan, S.-Y. Wang, L. Wang, X.-F. Williams, S.C. Wyatt, S. Zhang, T.-M. de Boer, T. Chambers, K. Gao, H. Magnier, E. INAF Osservatorio Astronomico di Padova Vicolo dell’Osservatorio 5 PadovaI-35122 Italy Universitá degli Studi di Padova Dipartimento di Fisica e Astronomia Vicolo dell’Osservatorio 2 Padova35122 Italy School of Physics O’Brien Centre for Science North University College Dublin Belfield Dublin 4 Ireland Instituto de astrofísica Facultad de Ciencias Exactas Universidad Andres Bello Fernández Concha 700 Las Condes Santiago Chile Nuncio Monsenor Sótero Sanz 100 Providencia Santiago8320000 Chile Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain Department of Astronomy University of California BerkeleyCA94720-3411 United States Miller Institute for Basic Research in Science University of California BerkeleyCA94720 United States Department of Astronomy and Astrophysics University of California Santa CruzCA95064 United States Tuorla Observatory Department of Physics and Astronomy University of Turku TurkuFI-20014 Finland Niels Bohr Institute University of Copenhagen Jagtvej 128 København N2200 Denmark Department of Physics and Astronomy University of California Davis 1 Shields Avenue DavisCA95616-5270 United States Gemini Observatory 670 North A’ohoku Place HiloHI96720-2700 United States Department of Physics Virginia Tech 850 West Campus Drive BlacksburgVA24061 United States DIRAC Institute Department of Astronomy University of Washington 3910 15th Avenue NE SeattleWA98195-0002 United States Las Cumbres Observatory 6740 Cortona Dr. Suite 102 GoletaCA93117 United States Department of Physics University of California Santa BarbaraCA93106 United States Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Tsinghua University Beijing100084 China School of Physics Trinity College Dublin The University of Dublin Dublin 2 Ireland Fondazione Bruno Kessler TrentoI-38123 Italy

We present photometric and spectroscopic data on three extragalactic luminous red novae (LRNe): AT 2018bwo, AT 2021afy, and AT 2021blu. AT 2018bwo was discovered in NGC 45 (at about 6.8 Mpc) a few weeks after the outburst onset. During the monitoring period, the transient reached a peak luminosity of 1040 erg s−1. AT 2021afy, hosted by UGC 10043 (∼ 49.2 Mpc), showed a double-peaked light curve, with the two peaks reaching a similar luminosity of 2.1(±0.6) × 1041 erg s−1. Finally, for AT 2021blu in UGC 5829 (∼ 8.6 Mpc), the pre-outburst phase was well-monitored by several photometric surveys, and the object showed a slow luminosity rise before the outburst. The light curve of AT 2021blu was sampled with an unprecedented cadence until the object disappeared behind the Sun, and it was then recovered at late phases. The light curve of LRN AT 2021blu shows a double peak, with a prominent early maximum reaching a luminosity of 6.5 × 1040 erg s−1, which is half of that of AT 2021afy. The spectra of AT 2021afy and AT 2021blu display the expected evolution for LRNe: a blue continuum dominated by prominent Balmer lines in emission during the first peak, and a redder continuum consistent with that of a K-type star with narrow absorption metal lines during the second, broad maximum. The spectra of AT 2018bwo are markedly different, with a very red continuum dominated by broad molecular features in absorption. As these spectra closely resemble those of LRNe after the second peak, AT 2018bwo was probably discovered at the very late evolutionary stages. This would explain its fast evolution and the spectral properties compatible with that of an M-type star. From the analysis of deep frames of the LRN sites years before the outburst, and considerations of the light curves, the quiescent progenitor systems of the three LRNe were likely massive, with primaries ranging from about 13 M for AT 2018bwo, to 14+−41 M for AT 2021blu, and over 40 M for AT 2021afy. Copyright © 2022, The Autho

关键词： Luminance

Optical Observations of the 2002cx-like Supernova 2014ek, and Characterizations of SNe Iax

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arXiv 2018年

作者： Li, Linyi Wang, Xiaofeng Zhang, Jujia Arcavi, Iair Zhang, Tianmeng Rui, Liming Hosseinzadeh, Griffin Howell, D. Andrew McCully, Curtis Zhang, Kaicheng Valenti, Stefano Mo, Jun Li, Wenxiong Huang, Fang Xiang, Danfeng Wang, Lifan Zhou, Xu Tsinghua University Beijing100084 China 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 Las Cumbres Observatory 6740 Cortona Dr Suite 102 GoletaCA93117-5575 United States Department of Physics University of California Santa BarbaraCA93106-9530 United States Key Laboratory of Optical Astronomy National Astronomical Observatories of China Chinese Academy of Sciences Beijing100012 China School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing101408 China Department of Physics University of California DavisCA95616 United States Department of Astronomy Shanghai Jiao Tong University Shanghai200240 China George P. and Cynthia Woods Mitchell Institute for Fundamental Physics & Astronomy Texas A. & M. University College StationTX77843 United States Purple Mountain Observatory Chinese Academy of Sciences Nanjing210034 China

We present optical observations of supernova (SN) 2014ek discovered during the Tsinghua-NAOC Transient Survey (TNTS), which shows properties that are consistent with those of SN 2002cx-like events (dubbed as SNe Iax). The photometry indicates that it is underluminous compared to normal SNe Ia, with the absolute V-band peak magnitude being as −17.66±0.20 mag. The spectra are characterized by highly ionized Fe iii and intermediate-mass elements (IMEs). The expansion velocity of the ejecta is found to be ∼5000 km s−1 near the maximum light, only half of that measured for normal SNe Ia. The overall spectral evolution is quite similar to SN 2002cx and SN 2005hk, while the absorption features of the main IMEs seem to be relatively weaker. The 56Ni mass synthesized in the explosion is estimated to be about 0.08 M from the pseudo bolometric light curve. Based on a large sample of SNe Iax, we examined the relations between peak luminosity, ejecta velocity, decline rate, and peak V−R color but did not find noticeable correlations between these observables, in particular when a few extreme events like SN 2008ha are excluded in the analysis. For this sample, we also studied the birthplace environments and confirm that they still hold the trend of occurring preferentially in late-type spiral galaxies. Moreover, SNe Iax tend to occur in large star-forming regions of their host galaxies, more similar to SNe Ibc than SNe II, favoring that their progenitors should be associated with very young stellar populations. Copyright © 2018, The Authors. All rights reserved.

关键词： Supernovae

Effects of magnetic fields on equation of state of rotating stars

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Science China(Physics,Mechanics & Astronomy) 2015年第2期58卷 109-113页

作者： NA WeiWei LIN GuiFang HUANG RunQian Department of Physics Yunnan University Department of Physics Yuxi Normal University Yunnan Observatories Chinese Academy of Sciences Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

The evolution of rotating stars with magnetic fields has been studied with focus given to the following aspects: the effects of magnetic fields on equation of state for stellar matter and the thermodynamic quantities; the effects of magnetic energy and pressure on the internal structure of stars. The differences between the structure and evolution of a 15M⊙rotating star with and without magnetic fields are discussed. Our results show that the magnetic fields have an effect on the structure and evolution of the star mainly during the central helium burning phase; and this influences the physical quantities in the stellar envelope where hydrogen and helium are partially ionized. This may influence stellar pulsation.

关键词： stars： magnetic fields stars： evolution stars： equation of state

Comparison between the time-integrated spectrum and the peak time spectrum of gamma-ray bursts and possible implications

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Science China(Physics,Mechanics & Astronomy) 2015年第3期58卷 82-89页

作者： LYU Fen WANG YuanZhu LIANG YunFeng LIN TingTing HU YouDong LIANG EnWei Department of Physics and GXU-NAOC Center for Astrophysics and Space Sciences Guangxi University Purple Mountain Observatory Chinese Academy of Sciences Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

The mono-frequency peak luminosity and the corresponding photon energy of the time-integrated （L~, Eg） and peak time （L~, ffp） vfv spectra were derived for a sample of 38 redshift-known Fermi GRBs by fitting the spectra with the Band function. It was found that Ept is generally consistent with Ep, and Lp is averagely three times larger than Lp. The slope of the Lp1 -Etp relation was consistent with that of the Lps - Eps relation. The photon indices in the peak time spectrum, particularly, the index of the low energy end was, were statistically larger than that in the time-integrated spectrum. These results indicate that Lp and Ep are dominated by Lp1 and Ept, respectively. The difference of the spectral indices between the time-integrated and peak time spectra may be because of the overlap effect of a series of time-resolved spectra within a GRB. Our simulations, which were based on the observed spectral evolution and correlation between the energy flux and the peak energy within individual GRBs support our speculations. The Lt - Et, relation may be less contaminated by the overla!a effect, and it would may be an intrinsic feature of radiation ohvsics.

关键词： γ-ray sources γ-ray bursts gamma-rays： astronomical observations

The bright star survey telescope for the planetary transit survey in Antarctica

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Science Bulletin 2016年第5期61卷 383-390页

作者： Qiguo Tian Peng Jiang Fujia Du Jian Wang Zhengyang Li Xiaoyan Li Zhiyong Zhang Haiping Lu Xiangyan Yuan Huigen Liu Hui Zhang Luming Sun Liang Chang Jianguo Wang Shaohua Zhang Tuo Ji Xiheng Shi Jie Chen Guangyu Zhang Minghao Jia Jiajing Liu Junyan Zhou Xiang Pan Shucheng Dong Fengxin Jiang Hongfei Zhang Jilin Zhou Lifan Wang Hongyan Zhou Polar Research Institute of China Shanghai 200136 China School of Astronomy and Space Science Nanjing UniversityNanjing 210093 China National Astronomical Observatories/Nanjing Institute of Astronomical Optics and Technology Chinese Academy of Sciences Nanjing 210042 China State Key Laboratory of Technologies of Particle Detection and Electronics Department of Modern Physics University of Science and Technology of China Hefei 230026 China Key Laboratory of Modern Astronomy and Astrophysics(Nanjing University) Ministry of Education Nanjing 210093China Key Laboratory for Research in Galaxies and Cosmology Department of Astronomy University of Science and Technology of China Chinese Academy of Sciences Hefei 230026 China National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China Purple Mountain Observatory Chinese Academy of ScienceNanjing 210008 China

Transiting extrasolar planets(exoplanets),especially those orbiting bright stars, are desired for study of the diversity of planetary compositions, internal structures and atmospheres beyond our solar system. Dome A at Antarctica is a promising site for planetary transit surveys,where the continuous darkness and the large clear-sky fraction in the winter months greatly enhance the detection efficiency. The Chinese Small Telescope ARray and the Antarctic Survey Telescopes are the first facilities that have been operated at Dome A for use in exoplanet surveys. To increase the sky coverage, a low-temperature-resistant wide-field robotic telescope, named the bright star survey telescope(BSST), has been developed to join the ongoing planetary transit survey in Antarctica. The BSST has an aperture size of 300 mm and is equipped with a largeframe 4K×4K CCD camera to receive starlight from a 3.°4×3.°4 field of view. The BSST was operated at Lijiang observatory in April and May 2015 for a test *** precision of 3.5 mmag was achieved for stars with V～11 mag using 75 s exposures. The transiting events of two Jupiter-size exoplanets, HAT-P-3b and HATP-12 b, were observed on May 10 and May 20, 2015,respectively.

关键词： Instrumentation Exoplanet Photometry Antarctic Site

A Gamma-ray Pulsar Timing Array Constrains the Nanohertz Gravitational Wave Background

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arXiv 2022年

作者： Ajello, M. Atwood, W.B. Baldini, L. Ballet, J. Barbiellini, G. Bastieri, D. Bellazzini, R. Berretta, A. Bhattacharyya, B. Bissaldi, E. Blandford, R.D. Bloom, E. Bonino, R. Bruel, P. Buehler, R. Burns, E. Buson, S. Cameron, R.A. Caraveo, P.A. Cavazzuti, E. Cibrario, N. Ciprini, S. Clark, C.J. Cognard, I. Coronado-Blázquez, J. Crnogorcevic, M. Cromartie, H. Crowter, K. Cutini, S. D’Ammando, F. De Gaetano, S. de Palma, F. Digel, S.W. Di Lalla, N. Dirirsa, F. Fana Di Venere, L. Domínguez, A. Ferrara, E.C. Fiori, A. Franckowiak, A. Fukazawa, Y. Funk, S. Fusco, P. Gammaldi, V. Gargano, F. Gasparrini, D. Giglietto, N. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guillemot, L. Guiriec, S. Gustafsson, M. Harding, A.K. Hays, E. Hewitt, J.W. Horan, D. Hou, X. Jóhannesson, G. Keith, M.J. Kerr, M. Kramer, M. Kuss, M. Larsson, S. Latronico, L. Li, J. Longo, F. Loparco, F. Lovellette, M.N. Lubrano, P. Maldera, S. Manfreda, A. Martí-Devesa, G. Mazziotta, M.N. Mereu, I. Michelson, P.F. Mirabal, N. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Morselli, A. Negro, M. Nieder, L. Ojha, R. Omodei, N. Orienti, M. Orlando, E. Ormes, J.F. Paneque, D. Parthasarathy, Aditya Pei, Z. Persic, M. Pesce-Rollins, M. Pillera, R. Poon, H. Porter, T.A. Principe, G. Racusin, J.L. Rainò, S. Rando, R. Rani, B. Ransom, S.M. Ray, P.S. Razzano, M. Razzaque, S. Reimer, A. Reimer, O. Roy, J. Sánchez-Conde, M. Saz Parkinson, P.M. Scargle, J. Scotton, L. Serini, D. Sgrò, C. Siskind, E.J. Smith, D.A. Spandre, G. Spiewak, R. Spinelli, P. Stairs, I. Suson, D.J. Swihart, S.J. Tabassum, S. Thayer, J.B. Theureau, G. Torres, D.F. Troja, E. Valverde, J. Wadiasingh, Z. Wood, K. Zaharijas, G. Department of Physics and Astronomy Clemson University Kinard Lab of Physics ClemsonSC29634-0978 United States Santa Cruz Institute for Particle Physics Department of Physics Department of Astronomy and Astrophysics University of California at Santa Cruz Santa CruzCA95064 United States Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy AIM CEA CNRS Université Paris-Saclay Université de Paris Gif-sur-Yvette F-91191 France Istituto Nazionale di Fisica Nucleare Sezione di Trieste TriesteI-34127 Italy Dipartimento di Fisica Università di Trieste TriesteI-34127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova PadovaI-35131 Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Dipartimento di Fisica Università degli Studi di Perugia PerugiaI-06123 Italy National Centre for Radio Astrophysics Tata Institute of Fundamental Research Pune411 007 India Dipartimento di Fisica "M. Merlin" Università e del Politecnico di Bari via Amendola 173 BariI-70126 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy 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 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 École polytechnique Centre national de la recherche scientifique Institut national de physique nucléaire de physique des particules Palaiseau F-91128 France Deutsches Elektronen Synchrotron Zeuthen D-15738 Germany Department of Physics and Astronomy Louisiana State University Baton RougeLA70803 United States Institut für Theoretische Physik and Astrophysik Unive

After large galaxies merge, their central supermassive black holes are expected to form binary systems whose orbital motion generates a gravitational wave background (GWB) at nanohertz frequencies. Searches for this background utilize pulsar timing arrays, which perform long-term monitoring of millisecond pulsars (MSPs) at radio wavelengths. We use 12.5 years of Fermi Large Area Telescope data to form a gamma-ray pulsar timing array. Results from 35 bright gamma-ray pulsars place a 95% credible limit on the GWB characteristic strain of 1.0 × 10−14 at 1 yr−1, which scales as the observing time span t−13/6obs. This direct measurement provides an independent probe of the GWB while offering a check on radio noise models. Copyright © 2022, The Authors. All rights reserved.

关键词： Pulsars

Optical quasi-periodic oscillation of the BL Lacertae object S5 0716+714 during the faint state

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arXiv 2017年

作者： Hong, Shanwei Xiong, Dingrong Bai, Jinming Yunnan Observatories Chinese Academy of Sciences 396 Yangfangwang Guandu District Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China School of Applied Technology Lijiang Teachers College Lijiang674199 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

In order to search for the evidence of quasi-periodic oscillation (QPO) in blazar, multicolor optical observations of the BL Lacertae object S5 0716+714 were performed from 2005 to 2012. For I band on March 19 2010 with low variability amplitude and low flux level, the same quasi-periodic oscillation 50 minutes with 99% significance levels is confirmed by ZDCF method, Lomb-Scargle method, REDFIT and fitting sinusoidal curves. The observed QPO is likely to be explained by accretion disk variability. If the observed QPO indicates an innermost stable orbital period from the accretion disk, the QPO 50 min corresponds to a black hole mass of 5.03×106M☉ for a non-rotating Schwarzschild black hole and 3.2 × 107M☉ for a maximally rotating Kerr black hole. Copyright © 2017, The Authors. All rights reserved.

关键词： Gravitation