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GRANDMA and HXMT Observations of GRB 221009A - the Standard-Luminosity Afterglow of a Hyper-Luminous Gamma-Ray Burst

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arXiv 2023年

作者： Kann, D.A. Agayeva, S. Aivazyan, V. Alishov, S. Andrade, C.M. Antier, S. Baransky, A. Bendjoya, P. Benkhaldoun, Z. Beradze, S. Berezin, D. Boër, M. Broens, E. Brunier, S. Bulla, M. Burkhonov, O. Burns, E. Chen, Y. Chen, Y.P. Conti, M. Coughlin, M.W. Cui, W.W. Daigne, F. Delaveau, B. Devillepoix, H.A.R. Dietrich, T. Dornic, D. Dubois, F. Ducoin, J.-G. Durand, E. Duverne, P.-A. Eggenstein, H.-B. Ehgamberdiev, S. Fouad, A. Freeberg, M. Froebrich, D. Ge, M.Y. Gervasoni, S. Godunova, V. Gokuldass, P. Gurbanov, E. Han, D.W. Hasanov, E. Hello, P. Hussenot-Desenonges, T. Inasaridze, R. Iskandar, A. Ismailov, N. Janati, A. du Laz, T. Jegou Jia, S.M. Karpov, S. Kaeouach, A. Kiendrebeogo, R.W. Klotz, A. Kneip, R. Kochiashvili, N. Kunert, N. Lekic, A. Leonini, S. Li, C.K. Li, W. Li, X.B. Liao, J.Y. Logie, L. Lu, F.J. Mao, J. Marchais, D. Ménard, R. Morris, D. Natsvlishvili, R. Nedora, V. Noonan, K. Noysena, K. Orange, N.B. Pang, P.T.H. Peng, H.W. Pellouin, C. Peloton, J. Pradier, T. Pyshna, O. Rajabov, Y. Rau, S. Rinner, C. Rivet, J.-P. Romanov, F.D. Rosi, P. Rupchandani, V.A. Serrau, M. Shokry, A. Simon, A. Smith, K. Sokoliuk, O. Soliman, M. Song, L.M. Takey, A. Tillayev, Y. Ramirez, L.M. Tinjaca Melo, I. Tosta e Turpin, D. de Ugarte Postigo, A. Vanaverbeke, S. Vasylenko, V. Vernet, D. Vidadi, Z. Wang, C. Wang, J. Wang, L.T. Wang, X.F. Xiong, S.L. Xu, Y.P. Xue, W.C. Zeng, X. Zhang, S.N. Zhao, H.S. Zhao, X.F. Hessian Research Cluster ELEMENTS Giersch Science Center Goethe University Frankfurt Campus Riedberg Max-von-Laue-Straße 12 Frankfurt am Main60438 Germany N. Tusi Shamakhy Astrophysical Observatory Azerbaijan National Academy of Sciences settl. Y. Mammadaliyev AZ Shamakhi5626 Azerbaijan E. Kharadze Georgian National Astrophysical Observatory Mt. Kanobili Abastumani Adigeni0301 Georgia Samtskhe-Javakheti State University Rustaveli Str. 113 Akhaltsikhe0080 Georgia School of Physics and Astronomy University of Minnesota MinneapolisMN55455 United States Artemis Observatoire de la Côte d’Azur Université Côte d’Azur Boulevard de l’Observatoire Nice06304 France Astronomical Observatory of Taras Shevchenko National University of Kyiv Observatorna Str. 3 Kyiv04053 Ukraine Laboratoire J.-L. Lagrange Université de Nice Sophia-Antipolis CNRS Observatoire de la Côte d’Azur Nice06304 France Oukaimeden Observatory High Energy Physics and Astrophysics Laboratory FSSM Cadi Ayyad University Av. Prince My Abdellah MarrakeshBP 2390 Morocco Main Astronomical Observatory of National Academy of Sciences of Ukraine 27 Acad. Zabolotnoho Str. Kyiv03143 Ukraine Vereniging Voor Sterrenkunde Balen-Neetlaan 18A Mol2400 Belgium Department of Physics and Earth Science University of Ferrara via Saragat 1 FerraraI-44122 Italy INFN Sezione di Ferrara via Saragat 1 FerraraI-44122 Italy INAF Osservatorio Astronomico d’Abruzzo via Mentore Maggini snc TeramoI-64100 Italy Ulugh Beg Astronomical Institute Uzbekistan Academy of Sciences Astronomy Str. 33 Tashkent100052 Uzbekistan Department of Physics & Astronomy Louisiana State University Baton RougeLA70803 United States Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China Montarrenti Observatory S. S. 73 Ponente Sovicille SienaI-53018 Italy Sorbonne Université CNRS UMR 7095 Institut d’Astrophysique de Paris 98 bis bd Arago Paris75014 Fra

GRB 221009A is the brightest Gamma-Ray Burst (GRB) detected in more than 50 years of study. In this paper, we present observations in the X-ray and optical domains ranging from the prompt emission (optical coverage by all-sky cameras) up to 20 days after the GRB obtained by the GRANDMA Collaboration (which includes observations from more than 30 professional and amateur telescopes) and the Insight-HXMT Collaboration operating the X-ray telescope HXMT-LE. We study the optical afterglow with empirical fitting using the GRANDMA+HXMT-LE data sets, augmented with data from the literature up to 60 days. We then model numerically, using a Bayesian approach, the GRANDMA and HXMT-LE afterglow observations, that we augment with Swift-XRT and additional optical/NIR observations reported in the literature. We find that the GRB afterglow, extinguished by a large dust column, is most likely behind a combination of a large Milky-Way dust column combined with moderate low-metallicity dust in the host galaxy. Using the GRANDMA+HXMT-LE+XRT dataset, we find that the simplest model, where the observed afterglow is produced by synchrotron radiation at the forward external shock during the deceleration of a top-hat relativistic jet by a uniform medium, fits the multi-wavelength observations only moderately well, with a tension between the observed temporal and spectral evolution. This tension is confirmed when using the extended dataset. We find that the consideration of a jet structure (Gaussian or power-law), the inclusion of synchrotron self-Compton emission, or the presence of an underlying supernova do not improve the predictions, showing that the modelling of GRB22109A will require going beyond the most standard GRB afterglow model. Placed in the global context of GRB optical afterglows, we find the afterglow of GRB 221009A is luminous but not extraordinarily so, highlighting that some aspects of this GRB do not deviate from the global known sample despite its extreme energetics an

关键词： Dust

TESS Cycle 2 observations of roAp stars with 2-min cadence data

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arXiv 2023年

作者： Holdsworth, D.L. Cunha, M.S. Lares-Martiz, M. Kurtz, D.W. Antoci, V. Barceló Forteza, S. De Cat, P. Derekas, A. Kayhan, C. Ozuyar, D. Skarka, M. Hey, D.R. Shi, F. Bowman, D.M. Kobzar, O. Ayala Gómez, A. Bognár, Zs. Buzasi, D.L. Ebadi, M. Fox-Machado, L. García Hernández, A. Ghasemi, H. Guzik, J.A. Handberg, R. Handler, G. Hasanzadeh, A. Jayaraman, R. Khalack, V. Kochukhov, O. Lovekin, C.C. Mikolajczyk, P. Mkrtichian, D. Murphy, S.J. Niemczura, E. Olafsson, B.G. Pascual-Granado, J. Paunzen, E. Posilek, N. Ramón-Ballesta, A. Safari, H. Samadi-Ghadim, A. Smalley, B. Sódor, Á. Stateva, I. Suárez, J.C. Szabó, R. Wu, T. Ziaali, E. Zong, W. Seager, S. Jeremiah Horrocks Institute University of Central Lancashire PrestonPR1 2HE United Kingdom South African Astronomical Observatory P.O. Box 9 Observatory Cape Town7935 South Africa Instituto de Astrofísica e Ciências do Espaço Universidade do Porto CAUP Rua das Estrelas PortoPT4150-762 Portugal Stellar Variability Group Institute of Astrophysics of Andalusia Department of Stellar Physics IAA-CSIC Granada Spain Centre for Space Research North-West University Mahikeng2745 South Africa National Space Institute Technical University of Denmark Elektrovej Kgs. LyngbyDK-2800 Denmark Granada18071 Spain Royal Observatory of Belgium Ringlaan 3 BrusselsB-1180 Belgium ELTE Eötvös Loránd University Gothard Astrophysical Observatory Szent Imre h. u. 112. SzombathelyH-9700 Hungary MTA-ELTE Lendület "Momentum" Milky Way Research Group Hungary HUN-RENSZTE Stellar Astrophysics Research Group Szegedi út Kt. 766 BajaH-6500 Hungary Department of Astronomy and Space Sciences Science Faculty Erciyes University Kayseri Melikgazi38030 Turkey Ankara University Faculty of Science Dept. of Astronomy and Space Sciences Tandogan Ankara06100 Turkey Astronomical Institute of the Czech Academy of Sciences Fričova 298 OndřejovCZ-25165 Czech Republic Department of Theoretical Physics and Astrophysics Masaryk University Kotlářská 2 BrnoCZ-61137 Czech Republic Institute for Astronomy University of Hawaii Honolulu United States Department of Astronomy Peking University Beijing100871 China The Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China School of Mathematics Statistics and Physics Newcastle University Newcastle upon TyneNE1 7RU United Kingdom Institute of Astronomy KU Leuven Leuven3001 Belgium Département de Physique et dÁstronomie Université de Moncton MonctonNBE1A 3E9 Canada Virtualmech R&D division Parque Empresarial Nuevo Torneo. Arquitectura 1 Sevilla41015 Spain Konkoly Observatory HUN-REN Research Centre for

We present the results of a systematic search of the Transiting Exoplanet Survey Satellite (TESS) 2-min cadence data for new rapidly oscillating Ap (roAp) stars observed during the Cycle 2 phase of its mission. We find seven new roAp stars previously unreported as such and present the analysis of a further 25 roAp stars that are already known. Three of the new stars show multiperiodic pulsations, while all new members are rotationally variable stars, leading to almost 70 per cent (22) of the roAp stars presented being α2 CVn-type variable stars. We show that targeted observations of known chemically peculiar stars are likely to overlook many new roAp stars, and demonstrate that multi-epoch observations are necessary to see pulsational behaviour changes. We find a lack of roAp stars close to the blue edge of the theoretical roAp instability strip, and reaffirm that mode instability is observed more frequently with precise, space-based observations. In addition to the Cycle 2 observations, we analyse TESS data for all known roAp stars. This amounts to 18 further roAp stars observed by TESS. Finally, we list six known roAp stars that TESS is yet to observe. We deduce that the incidence of roAp stars amongst the Ap star population is just 5.5 per cent, raising fundamental questions about the conditions required to excite pulsations in Ap stars. This work, coupled with our previous work on roAp stars in Cycle 1 observations, presents the most comprehensive, homogeneous study of the roAp stars in the TESS nominal mission, with a collection of 112 confirmed roAp stars in total. © 2023, CC BY.

关键词： Stars

Can turbulence dominate depolarization of optical blazars?

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arXiv 2017年

作者： Guo, Xiaotong Mao, Jirong Wang, Jiancheng Yunnan Observatories Chinese Academy of Sciences Kunming Yunnan Province650011 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang Dis-trict Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China University of Chinese Academy of Sciences Beijing100049 China

We carefully examine the depolarization feature of blazars in the optical and near-infrared bands using the sample of Mead et al. Magnetohydrodynamics (MHD) turbulence could be one possible reason for the depolarization of optical/infrared blazars when we apply the theoretical analysis of Lazarian & Pogosyan. We further identify in the sample that the depolarization results shown in most blazars roughly obey the form of the three-dimensional anisotropic Kolmogorov scaling. The effective Faraday rotation window length scale is not small enough to resolve the polarization correlation length scale in the blazar sample. The depolarization and the related turbulent features show diversities in different blazar sources. We suggest more simultaneous observations in both the optical/infrared and the high-energy bands for the study of the blazar polarization. Copyright © 2017, The Authors. All rights reserved.

关键词： Depolarization

Variable stars in the open cluster NGC 2141

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Research in Astronomy and Astrophysics 2015年第5期15卷 733-741页

作者： Yang-Ping Luo School of Physics & Electronic Information China West Normal University Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences

We report the results of a search for variable stars in the open cluster NGC 2141. Ten variable stars are detected, among which nine are new variable stars and they are classified as three short-period W UMa-type eclipsing binaries, two EA- type eclipsing binaries, one EB-type eclipsing binary, one very short-period RS CVn- type eclipsing binary, one d-type RR Lyrae variable star, and one unknown type of variable star. The membership and physical properties are discussed, based on their light curves, positions in the color magnitude diagrams, spatial locations and periods. A known EB-type eclipsing binary is also identified as a blue straggler candidate in the cluster. Furthermore, we find that all eclipsing contact binaries have prominent asymmetric eclipses and display the O＇Connell effect, which increases with a decrease in orbital periods. This suggests that the O＇Connell effect is probably related to the evolution of the orbital period in short period eclipsing binary systems.

关键词： stars binaries general -- open clusters and associations individual （NGC 2141） -- variables general

Possible quasi-periodic modulation in the z = 1.1 γ-ray blazar PKS 0426-380

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arXiv 2017年

作者： Zhang, Peng-fei Yan, Da-hai Liao, Neng-hui Zeng, Wei Wang, Jian-cheng Cao, Li-Jia Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Nanjing210008 China Yunnan Observatory Chinese Academy of Sciences Kunming650011 China Key Laboratory of Astroparticle Physics of Yunnan Province Yunnan University Kunming650091 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

We search for γ-ray and optical periodic modulations in a distant flat spectrum radio quasar (FSRQ) PKS 0426-380 (the redshift z = 1.1). Using two techniques (i.e., the maximum likelihood optimization and the exposure-weighted aperture photometry), we obtain γ-ray light curves from Fermi-LAT Pass 8 data covering from 2008 August to 2016 December. We then analyze the light curves with the Lomb-Scargle Periodogram (LSP) and the Weighted Wavelet Z-transform (WWZ). A γ-ray quasi-periodicity with a period of 3.35 ± 0.68 years is found at the significance-level of ' 3.6 σ. The optical-UV flux covering from 2005 August to 2013 April provided by ASI SCIENCE DATA CENTER is also analyzed, but no significant quasi-periodicity is found. It should be pointed out that the result of the optical-UV data could be tentative because of the incomplete of the data. Further long-term multiwavelength monitoring of this FSRQ is needed to confirm its quasi-periodicity. Copyright © 2017, The Authors. All rights reserved.

关键词： Gamma rays

X-ray light curve in GRB 170714a: evidence for quark star?

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arXiv 2017年

作者： Hou, Shu-Jin Liu, Tong Xu, Ren-Xin Mu, Hui-Jun Song, Cui-Ying Lin, Da-Bin Gu, Wei-Min College of Physics and Electronic Engineering Nanyang Normal University Nanyang Henan473061 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming Yunnan650011 China Laboratory for Relativistic Astrophysics Department of Physics Guangxi University Nanning Guangxi530004 China Department of Astronomy Xiamen University XiamenFujian361005 China School of Physics Peking University Beijing100871 China

Two plateaus and one following bump in the X-ray light curve of GRB 170714A have been detected by the Swift/X-Ray Telescope, which could be very meaningful for the central engine of gamma-ray bursts (GRBs), implying that the origin of this burst might be different from that of other ultra-long GRBs. We propose that merging two neutron stars into a hyper-massive quark star (QS) and then collapsing into a black hole (BH), with a delay time around 104 s, could be responsible for those X-ray components. The hyper-massive QS is initially in a fluid state, being turbulent and differentially rotating, but would be solidified and release its latent heat injected into the GRB fireball (lasting about 103 s during the liquid-solid phase transition). Magnetic field as high as ∼ 1015 G could be created by dynamo action of the newborn liquid QS, and a magnetar-like central engine (after solidification) supplies significant energy for the second plateau. More energy could be released during a fall-back accretion after the post-merger QS collapses to a BH, and the X-ray bump forms. This post-merger QS model might be tested by future observations, with either advanced gravitational wave detectors (e.g., advanced LIGO and VIRGO) or X-ray/optical telescopes. Copyright © 2017, The Authors. All rights reserved.

关键词： Stars

Stellar and agn feedback in isolated early-type galaxies: The role in regulating star formation and ism properties

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arXiv 2018年

作者： LI, YA-PING YUAN, FENG MO, HOUJUN YOON, DOOSOO GAN, ZHAOMING HO, LUIS C. WANG, BO OSTRIKER, JEREMIAH P. CIOTTI, LUCA Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China School of Astronomy and Space Sciences University of Chinese Academy of Sciences No. 19A Yuquan Road Beijing100049 China Department of Astronomy University of Massachusetts AmherstMA01003-9305 United States Tsinghua Center of Astrophysics and Department of Physics Tsinghua University Beijing100084 China Kavli Institute for Astronomy and Astrophysics Peking University Beijing100871 China Department of Astronomy School of Physics Peking University Beijing100871 China Key Laboratory for the Structure and Evolution of Celestial Objects Yunnan Observatories CAS Kunming650216 China Department of Astronomy Columbia University 550 W 120th Street New YorkNY10027 United States Department of Physics and Astronomy University of Bologna via Piero Gobetti 93/2 Bologna40129 Italy

Understanding how galaxies maintain the inefficiency of star formation with physically self-consistent models is a central problem for galaxy evolution. Although numerous theoretical models have been proposed in recent decades, the debate still exists. By means of high-resolution two-dimensional hydrodynamical simulations, we study the three feedback effects (the stellar wind heating, SNe feedback, and AGN feedback) in suppressing star formation activities on the evolution of early-type galaxies with different stellar masses. AGN feedback models are updated based on Yuan et al. (2018). The gas sources comes exclusively from the mass losses of dying low-mass stars for most of our models. We find that SNe feedback can keep star formation at a significantly low level for low mass elliptical galaxies for a cosmological evolution time. For the high mass galaxies, AGN feedback can efficiently offset the radiative cooling and thus regulate the star formation activities. Such a suppression of star formation is extremely efficient in the inner region of the galaxies. AGB heating cannot account for this suppression for low and high mass galaxies. The X-ray temperature TX and luminosity LX of hot plasma can be in agreement with the observed data with the inclusion of effective feedback processes. These results thus suggest that we can use TX and LX to probe the role of different feedback processes. The inclusion of additional gas sources can make the mass scale between SNe and AGN feedback dominating in suppressing star formation decrease to an observationally inferred value of a few 1010 Mo. Copyright © 2018, The Authors. All rights reserved.

关键词： Galaxies

SEARCH FOR NEW COSMIC-RAY ACCELERATION SITES WITHIN THE 4FGL CATALOG GALACTIC PLANE SOURCES

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arXiv 2022年

作者： Abdollahi, S. Acero, F. Ackermann, M. Baldini, L. Ballet, J. Barbiellini, G. Bastieri, D. Bellazzini, R. Berenji, B. Berretta, A. Bissaldi, E. Blandford, R.D. Bonino, R. Bruel, P. Buson, S. Cameron, R.A. Caputo, R. Caraveo, P.A. Castro, D. Chiaro, G. Cibrario, N. Ciprini, S. Coronado-Blázquez, J. Crnogorcevic, M. Cutini, S. D'Ammando, F. De Gaetano, S. Di Lalla, N. Dirirsa, F. Di Venere, L. Domínguez, A. Fegan, S.J. Fiori, A. Fleischhack, H. Franckowiak, A. Fukazawa, Y. Fusco, P. Gammaldi, V. Gargano, F. Gasparrini, D. Giacchino, F. Giglietto, N. Giordano, F. Giroletti, M. Glanzman, T. Green, D. Grenier, I.A. Grondin, M.-H. Guiriec, S. Gustafsson, M. Harding, A.K. Hays, E. Hewitt, J.W. Horan, D. Hou, X. Jóhannesson, G. Kayanoki, T. Kerr, M. Kuss, M. Larsson, S. Latronico, L. Lemoine-Goumard, M. Li, J. Longo, F. Loparco, F. Lubrano, P. Maldera, S. Malyshev, D. Manfreda, A. Martí-Devesa, G. Mazziotta, M.N. Mereu, I. Michelson, P.F. Mirabal, N. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Morselli, A. Moskalenko, I.V. Nuss, E. Omodei, N. Orienti, M. Orlando, E. Ormes, J.F. Paneque, D. Pei, Z. Persic, M. Pesce-Rollins, M. Pillera, R. Poon, H. Porter, T.A. Principe, G. Rainò, S. Rando, R. Rani, B. Razzano, M. Razzaque, S. Reimer, A. Reimer, O. Reposeur, T. Sánchez-Conde, M. Parkinson, P.M. Saz Scotton, L. Serini, D. Sgrò, C. Siskind, E.J. Spandre, G. Spinelli, P. Sueoka, K. Suson, D.J. Tajima, H. Tak, D. Thayer, J.B. Torres, D.F. Troja, E. Valverde, J. Wadiasingh, Z. Wood, K. Zaharijas, G. IRAP Université de Toulouse CNRS UPS CNES ToulouseF-31028 France Université Paris Saclay Université Paris Cité CEA CNRS AIM Gif-sur-Yvette F-91191 France Deutsches Elektronen Synchrotron DESY ZeuthenD-15738 Germany Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy 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 Center for Space Studies and Activities "G. Colombo" University of Padova Via Venezia 15 PadovaI-35131 Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy California State University Los Angeles Department of Physics and Astronomy Los AngelesCA90032 United States Dipartimento di Fisica Università degli Studi di Perugia PerugiaI-06123 Italy 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 CNRS IN2P3 PalaiseauF-91128 France Institut für Theoretische Physik and Astrophysik Universität Würzburg WürzburgD-97074 Germany NASA Goddard Space Flight Center GreenbeltMD20771 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 Is

Cosmic rays are mostly composed of protons accelerated to relativistic speeds. When those protons encounter interstellar material, they produce neutral pions which in turn decay into gamma rays. This offers a compelling way to identify the acceleration sites of protons. A characteristic hadronic spectrum, with a low-energy break around 200 MeV, was detected in the gamma-ray spectra of four Supernova Remnants (SNRs), IC 443, W44, W49B and W51C, with the Fermi Large Area Telescope. This detection provided direct evidence that cosmic-ray protons are (re-)accelerated in SNRs. Here, we present a comprehensive search for low-energy spectral breaks among 311 4FGL catalog sources located within 5◦ from the Galactic plane. Using 8 years of data from the Fermi Large Area Telescope between 50 MeV and 1 GeV, we find and present the spectral characteristics of 56 sources with a spectral break confirmed by a thorough study of systematic uncertainty. Our population of sources includes 13 SNRs for which the proton-proton interaction is enhanced by the dense target material;the high-mass γ-ray binary LS I +61 303;the colliding wind binary η Carinae;and the Cygnus star-forming region. This analysis better constrains the origin of the γ-ray emission and enlarges our view to potential new cosmic-ray acceleration sites. Copyright © 2022, The Authors. All rights reserved.

关键词： Cosmic rays

A 34.5 day quasi-periodic oscillation in γ-ray emission from the blazar PKS 2247–131

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arXiv 2018年

作者： Zhou, Jianeng Wang, Zhongxiang Chen, Liang Wiita, Paul J. Vadakkumthani, Jithesh Morrell, Nidia Zhang, Pengfei Zhang, Jujia Shanghai Astronomical Observatory Chinese Academy of Sciences 80 Nandan Road Shanghai200030 China University of Chinese Academy of Sciences 19A Yuquan Road Beijing100049 China The College of New Jersey 2000 Pennington Road EwingNJ 08628-0718 United States Inter-University Centre for Astronomy and Astrophysics Pune411 007 India Las Campanas Observatory Carnegie Observatories Casilla 601 La Serena 1700000 Chile Purple Mountain Observatory Chinese Academy of Sciences 8 Yuanhua Road Nanjing210034 China Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road BeijingChaoyang District100012 China

Since 2016 October, the active galaxy PKS 2247−131 has undergone a γ-ray outburst, which we studied using data obtained with the Fermi Gamma-ray Space Telescope. The emission arises from a relativistic jet in PKS 2247−131, as an optical spectrum only shows a few weak absorption lines, typical of the BL Lacertae sub-class of the blazar class of active galactic nuclei. Here we report a 34.5 day quasi-periodic oscillation (QPO) in the emission after the initial flux peak of the outburst. Compared to one-year time-scale QPOs, previously identified in blazars in Fermi energies, PKS 2247−131 exhibits the first clear case of a relatively short, month-like oscillation. We show that this QPO can be explained in terms of a helical structure in the jet, where the viewing angle to the dominant emission region in the jet undergoes periodic changes. The time scale of the QPO suggests the presence of binary supermassive black holes in PKS 2247−131. Copyright © 2018, The Authors. All rights reserved.

关键词： Absorption spectroscopy