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arXiv 2024年

作者： Valerin, G. Pastorello, A. Reguitti, A. Benetti, S. Cai, Y.-Z. Chen, T.-W. Eappachen, D. Elias-Rosa, N. Fraser, M. Gangopadhyay, A. Hsiao, E.Y. Howell, D.A. Inserra, C. Izzo, L. Jencson, J. Kankare, E. Kotak, R. Mazzali, P.A. Misra, K. Pignata, G. Prentice, S.J. Sand, D.J. Smartt, S.J. Stritzinger, M.D. Tartaglia, L. Valenti, S. Anderson, J.P. Andrews, J.E. Amaro, R.C. Brennan, S. Bufano, F. Callis, E. Cappellaro, E. Dastidar, R. Della Valle, M. Fiore, A. Fulton, M.D. Galbany, L. Heikkilä, T. Hiramatsu, D. Karamehmetoglu, E. Kuncarayakti, H. Leloudas, G. Lundquist, M. McCully, C. Müller-Bravo, T.E. Nicholl, M. Ochner, P. Padilla Gonzalez, E. Paraskeva, E. Pellegrino, C. Reichart, D.E. Reynolds, T.M. Roy, R. Salmaso, I. Singh, M. Turatto, M. Tomasella, L. Wyatt, S. Young, D.R. INAF - Osservatorio Astronomico di Padova Vicolo dell'Osservatorio 5 PadovaI-35122 Italy INAF - Osservatorio Astronomico di Brera Via E. Bianchi 46 LC Merate23807 Italy Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China International Centre of Supernovae Yunnan Key Laboratory Kunming650216 China Graduate Institute of Astronomy National Central University 300 Jhongda Road Jhongli32001 Taiwan SRON Netherlands Institute for Space Research Niels Bohrweg 4 Leiden2333 CA Netherlands Department of Astrophysics IMAPP Radboud University Nijmegen P.O. Box 9010 Nijmegen6500 GL Netherlands Campus UAB Carrer de Can Magrans s/n BarcelonaE-08193 Spain School of Physics O'Brien Centre for Science North University College Dublin Belfield Dublin 4 Ireland The Oskar Klein Centre Department of Astronomy Stockholm University AlbaNova Stockholm10691 Sweden Hiroshima Astrophysical Science Center Hiroshima University Higashi-Hiroshima Japan Department of Physics Florida State University 77 Chieftan Way TallahasseeFL32306 United States Las Cumbres Observatory 6740 Cortona Dr. Suite 102 GoletaCA93117 United States Department of Physics University of California Santa BarbaraCA93106 United States School of Physics & Astronomy Cardiff University Queens Buildings The Parade CardiffCF24 3AA United Kingdom INAF Osservatorio Astronomico di Capodimonte Salita Moiariello 16 NapoliI-80131 Italy DARK Niels Bohr Institute University of Copenhagen Jagtvej 128 Copenhagen2200 Denmark Caltech Mail Code 220-6 PasadenaCA91125 United States Tuorla Observatory Department of Physics and Astronomy University of Turku Turku20014 Finland Astrophysics Research Institute Liverpool John Moores University IC2 Liverpool Science Park 146 Brownlow Hill LiverpoolL3 5RF United Kingdom Max-Planck-Institut für Astrophysik Karl-Schwarzs

Aims. We investigate the photometric characteristics of a sample of Intermediate Luminosity Red Transients (ILRTs), a class of elusive objects with peak luminosity between that of classical novae and standard supernovae. Our goal is to provide a stepping stone in the path to unveil the physical origin of such events, thanks to the analysis of the datasets collected. Methods. We present the multi-wavelength photometric follow-up of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd and AT 2019udc. Through the analysis and modelling of their spectral energy distribution and bolometric light curves we infer the physical parameters associated with these transients. Results. All four objects display a single peaked light curve which ends in a linear decline in magnitudes at late phases. A flux excess with respect to a single black body emission is detected in the infrared domain for three objects in our sample, a few months after maximum. This feature, commonly found in ILRTs, is interpreted as a sign of dust formation. Mid infrared monitoring of NGC 300 2008OT-1 761 days after maximum allows us to infer the presence of ∼10−3-10−5 Mo of dust, depending on the chemical composition and the grain size adopted. The late time decline of the bolometric light curves of the considered ILRTs is shallower than expected for 56Ni decay, hence requiring an additional powering mechanism. James Webb Space Telescope observations of AT 2019abn prove that the object has faded below its progenitor luminosity in the mid-infrared domain, five years after its peak. Together with the disappearance of NGC 300 2008OT-1 in Spitzer images seven years after its discovery, this supports the terminal explosion scenario for ILRTs. With a simple semi-analytical model we try to reproduce the observed bolometric light curves in the context of few Mo of material ejected at few 103 km s−1 and enshrouded in an optically thick circumstellar medium. © 2024, CC BY.

关键词： Giant stars

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SN 2018zd: An unusual stellar explosion as part of the diverse type II supernova landscape

arXiv

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arXiv 2020年

作者： Zhang, Jujia Wang, Xiaofeng Vinkó, József Zhai, Qian Zhang, Tianmeng Filippenko, Alexei V. Brink, Thomas G. Zheng, WeiKang Wyrzykowski, Lukasz Mikolajczyk, Przemyslaw Huang, Fang Rui, Liming Mo, Jun Sai, Hanna Zhang, Xinhan Wang, Huijuan DerKacy, James M. Baron, Eddie Sárneczky, K. Bódi, A. Csörnyei, G. Hanyecz, O. Ignácz, B. Kalup, Cs. Kriskovics, L. Könyves-Tóth, R. Ordasi, A. Pál, A. Sódor, Á. Szakáts, R. Vida, K. Zsidi, G. Kunming650216 China Chinese Academy of Sciences South America Center for Astronomy National Astronomical Observatories CAS Beijing100012 China Key Laboratory for the Structure and Evolution of Celestial Objects CAS Kunming650216 China Center for Astronomical Mega-Science CAS 20A Datun Road Chaoyang District Beijing100012 China Tsinghua University Beijing100084 China Beijing Planetarium Beijing Academy of Science and Technology Beijing100044 China Konkoly Observatory CSFK Konkoly-Thege M. ut 15-17 Budapest1121 Hungary ELTE Eötvös Loránd University Institute of Physics Pázmány Péter sétány 1/A Budapest1117 Hungary Department of Optics and Quantum Electronics University of Szeged Dóm tér 9 Szeged6720 Hungary 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 Beijing101408 China Department of Astronomy University of California BerkeleyCA94720-3411 United States Miller Institute for Basic Research in Science University of California BerkeleyCA94720 United States Astronomical Institute University of Wroclaw M. Kopernika 11 Wroclaw51-622 Poland Department of Astronomy Shanghai Jiao Tong University Shanghai200240 China Homer L. Dodge Department of Physics and Astronomy University of Oklahoma NormanOK73019 United States ELTE Eötvös Loránd University Department of Astronomy Pázmány Péter sétány 1/A Budapest1117 Hungary MTA CSFK Lendület Near-Field Cosmology Research Group Konkoly Observatory Budapest1121 Hungary European Southern Observatory Karl-Schwarzschild-Strasse 2 Garching bei München85748 Germany

We present extensive observations of SN 2018zd covering the first ∼ 450 d after the explosion. This SN shows a possible shock-breakout signal ∼ 3.6 hr after the explosion in the unfiltered light curve, and prominent flash-ionisation spectral features within the first week. The unusual photospheric temperature rise (rapidly from ∼ 12, 000 K to above 18,000 K) within the earliest few days suggests that the ejecta were continuously heated. Both the significant temperature rise and the flash spectral features can be explained with the interaction of the SN ejecta with the massive stellar wind (0.18+−000510 M), which accounts for the luminous peak (Lmax = [1.36±0.63]×1043 erg s−1) of SN 2018zd. The luminous peak and low expansion velocity (v ≈ 3300 km s−1) make SN 2018zd to be like a member of the LLEV (luminous SNe II with low expansion velocities) events originated due to circumstellar interaction. The relatively fast post-peak decline allows a classification of SN 2018zd as a transition event morphologically linking SNe IIP and SNe IIL. In the radioactive-decay phase, SN 2018zd experienced a significant flux drop and behaved more like a low-luminosity SN IIP both spectroscopically and photometrically. This contrast indicates that circumstellar interaction plays a vital role in modifying the observed light curves of SNe II. Comparing nebular-phase spectra with model predictions suggests that SN 2018zd arose from a star of ∼ 12 M . Given the relatively small amount of 56Ni (0.013 − 0.035M), the massive stellar wind, and the faint X-ray radiation, the progenitor of SN 2018zd could be a massive asymptotic giant branch star which collapsed owing to electron capture. Copyright © 2020, The Authors. All rights reserved.

关键词： Expansion

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Fermi-detection of γ-ray Emissions from the Hot Coronae of Radio-quiet Active Galactic Nuclei

arXiv

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arXiv 2025年

作者： Abdollahi, S. Ajello, M. Alves Batista, R. Baldini, L. Bartolini, C. Bastieri, D. Becerra Gonzalez, J. Bellazzini, R. Berenji, B. Bissaldi, E. Blandford, R.D. Bonino, R. Bruel, P. Buson, S. Cameron, R.A. Caraveo, P.A. Cavazzuti, E. Chiaro, G. Cibrario, N. Ciprini, S. Cristarella Orestano, P. Cutini, S. D’Ammando, F. Di Lalla, N. Dinesh, A. Di Venere, L. Domínguez, A. Fegan, S.J. Fiori, A. Franckowiak, A. Fukazawa, Y. Funk, S. Fusco, P. Gargano, F. Gasbarra, C. Gasparrini, D. Germani, S. Giglietto, N. Giliberti, M. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guiriec, S. Hashizume, M. Hays, E. Hewitt, J.W. Horan, D. Hou, Xian Karwin, C. Kayanoki, T. Kuss, M. Laviron, A. Lemoine-Goumard, M. Li, Jian Liodakis, I. Liu, Jun-Rong Longo, F. Loparco, F. Lorusso, L. Lubrano, P. Maldera, S. Marcotulli, L. Martí-Devesa, G. Mazziotta, M.N. Mereu, I. Michelson, P.F. Mirabal, N. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Morishita, T. Morselli, A. Moskalenko, I.V. Negro, M. Niwa, R. Omodei, N. Orienti, M. Orlando, E. Ormes, J.F. Paneque, D. Panzarini, G. Persic, M. Pesce-Rollins, M. Pillera, R. Porter, T.A. Principe, G. Rainò, S. Rando, R. Rani, B. Razzano, M. Reimer, A. Reimer, O. Sánchez-Conde, M. Saz Parkinson, P.M. Serini, D. Sgrò, C. Siskind, E.J. Spandre, G. Spinelli, P. Suson, D.J. Tajima, H. Thayer, J.B. Torres, D.F. Wang, Jian-Min Zhao, Zi-Hao Department of Physics and Astronomy Clemson University Kinard Lab of Physics ClemsonSC29634-0978 United States Instituto de Física Teórica UAM CSIC Universidad Autónoma de Madrid MadridE-28049 Spain Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy Università degli studi di Trento via Calepina 14 Trento38122 Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova Via F. Marzolo 8 PadovaI-35131 Italy Center for Space Studies and Activities "G. Colombo" University of Padova Via Venezia 15 PadovaI-35131 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 California State University Los Angeles Department of Physics and Astronomy Los AngelesCA90032 United States Dipartimento di Fisica "M. Merlin" dell’Università e del Politecnico di Bari via Amendola 173 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 CNRS IN2P3 École polytechnique Institut Polytechnique de Paris Palaiseau91120 France Institut für Theoretische Physik and Astrophysik Universität Würzburg WürzburgD-97074 Germany INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano via E. Bassini 15 MilanoI-20133 Italy Italian Space Agency Via del Politecnico snc Roma00133 Italy Istituto Nazionale di Fisica Nucleare Sezione di Roma "Tor Vergata" RomaI-00133 Italy Space Sci

Relativistic jets around supermassive black holes (SMBHs) are well-known powerful γ-ray emitters. In absence of the jets in radio-quiet active galactic nuclei (AGNs), how the SMBHs work in γ-ray bands is still unknown despite of great observational efforts made in the last 3 decades. Considering the previous efforts, we carefully select an AGN sample composed of 37 nearby Seyfert galaxies with ultra-hard X-rays for the goals of γ-ray detections by excluding all potential contamination in this band. Adopting a stacking technique, here we report the significant γ-ray detection (TS = 30.6, or 5.2 σ) from the sample using 15-year Fermi-Large Area Telescope (LAT) observation. We find an average γ-ray luminosity of the sample as (1.5 ± 1.0) × 1040 erg s−1 at energies from 1-300 GeV. Limited by the well-known pair production from the interaction of γ-rays with low energy photons, several GeV γ-rays are found to originate from an extended corona (∼ 2.7 × 106Rg), whereas the canonical much more compact X-ray corona (∼ 10Rg) is responsible for 1 to several GeV γ-rays. The finding of the compact region lends to strong supports to the long-time theoretical expectations, but the extended corona is beyond all the existing models. One promising scenario is that the electron-positron pairs produced in the compact X-ray corona would expand as fireball, similar to that in γ-ray bursts, forming the structure of extended corona. © 2025, CC BY.

关键词： Active Galactic Nuclei

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SEARCH FOR EXTENDED GEV SOURCES IN THE INNER GALACTIC PLANE

arXiv

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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

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EP240801a/XRF 240801B: An X-ray Flash Detected by the Einstein Probe and Implications of its Multiband Afterglow

arXiv

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arXiv 2025年

作者： Jiang, Shuai-Qing Xu, Dong van Hoof, Agnes P.C. Lei, Wei-Hua Liu, Yuan Zhou, Hao Chen, Yong Fu, Shao-Yu Yang, Jun Liu, Xing Zhu, Zi-Pei Filippenko, Alexei V. Jonker, Peter G. Pozanenko, A.S. Gao, He Wu, Xue-Feng Zhang, Bing Lamb, Gavin P. De Pasquale, Massimiliano Kobayashi, Shiho Bauer, Franz Erik Sun, Hui Pugliese, Giovanna An, Jie D’Elia, Valerio Fynbo, Johan P.U. Zheng, WeiKang Tirado, Alberto J.C. Yin, Yi-Han Iris Zou, Yuan-Chuan Deller, Adam T. Pankov, N.S. Volnova, A.A. Moskvitin, A.S. Spiridonova, O.I. Oparin, D.V. Rumyantsev, V. Burkhonov, O.A. Egamberdiyev, Sh A. Kim, V. Krugov, M. Tatarnikov, A.M. Inasaridze, R. Levan, Andrew J. Malesani, Daniele Bjørn Ravasio, Maria E. Quirola-Vásquez, Jonathan van Dalen, Joyce N.D. Sánchez-Sierras, Javi Sánchez, Daniel Mata Littlefair, Stuart P. Chacón, Jennifer A. Torres, Manuel A.P. Chrimes, Ashley A. Sarin, Nikhil Martin-Carrillo, Antonio Dhillon, Vik Yang, Yi Brink, Thomas G. Davies, Rebecca L. Yang, Sheng Aryan, Amar Chen, Ting-Wan Kong, Albert K.H. Li, Wen-Xiong Li, Rui-Zhi Mao, Jirong Pérez-García, Ignacio Fernández-García, Emilio J. Andrews, Moira Farah, Joseph Fan, Zhou Gonzalez, Estefania Padilla Howell, D. Andrew Hartmann, Dieter Hu, Jing-Wei Jakobsson, Páll Li, Cheng-Kui Ling, Zhi-Xing McCully, Curtis Newsome, Megan Schneider, Benjamin Tinyanont, Kaew Samaporn Sun, Ning-Chen Terreran, Giacomo Tang, Qing-Wen Wang, Wen-Xin Xu, Jing-Jing Yuan, Wei-Min Zhang, Bin-Bin Zhao, Hai-Sheng Zhang, Juan National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Astronomy and Space Science University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100049 China Altay Astronomical Observatory Xinjiang836500 China Radboud University Nijmegen Department of Astrophysics IMAPP P.O. Box 9010 Nijmegen6500 GL Netherlands Department of Astronomy School of Physics Huazhong University of Science and Technology Wuhan430074 China Purple Mountain Observatory Chinese Academy of Sciences Nanjing210023 China Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China School of Astronomy and Space Science Nanjing University Nanjing210093 China Key Laboratory of Modern Astronomy and Astrophysics [Nanjing University Ministry of Education China Department of Astronomy University of California BerkeleyCA94720-3411 United States Space Research Institute Russian Academy of Sciences Profsoyuznaya ul. 84/32 Moscow117997 Russia National Research University "Higher School of Economics" Myasnitskaya ul. 20 Moscow101000 Russia Institutskiy Pereulok 9 Dolgoprudny141701 Russia School of Physics and Astronomy Beijing Normal University Beijing100875 China Institute for Frontier in Astronomy and Astrophysics Beijing Normal University Beijing102206 China Nevada Center for Astrophysics University of Nevada Las Vegas NV89154 United States Department of Physics and Astronomy University of Nevada Las Vegas NV89154 United States Astrophysics Research Institute Liverpool John Moores University IC2 Liverpool Science Park 146 Brownlow Hill LiverpoolL3 5RF United Kingdom University of Messina MIFT Department Via F.S. D’Alcontres 31 Messina98166 Italy Instituto de Alta Investigación Universidad de Tarapacá Casilla 7D Arica Chile Anton Pannekoek Institute of Astronomy University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands RomaI-00133 It

We present multiband observations and analysis of EP240801a, a low-energy, extremely soft gammaray burst (GRB) discovered on August 1, 2024 by the Einstein Probe (EP) satellite, with a weak contemporaneous signal also detected by Fermi/GBM. Optical spectroscopy of the afterglow, obtained by GTC and Keck, identified the redshift of z = 1.6734. EP240801a exhibits a burst duration of 148 s in X-rays and 22.3 s in gamma-rays, with X-rays leading by 80.61 s. Spectral lag analysis indicates the gamma-ray signal arrived 8.3 s earlier than the X-rays. Joint spectral fitting of EP/WXT and Fermi/GBM data yields an isotropic energy Eγ,iso = (5.57+0−0.5450) × 1051 erg, a peak energy Epeak = 14.90+7−4.0871 keV, a fluence ratio S(25 − 50 keV)/S(50 − 100 keV) = 1.67+0−0.7446, classifying EP240801a as an X-ray flash (XRF). The host-galaxy continuum spectrum, inferred using Prospector, was used to correct its contribution for the observed outburst optical data. Unusual early R-band behavior and EP/FXT observations suggest multiple components in the afterglow. Three models are considered: two-component jet model, forward-reverse shock model and forward-shock model with energy injection. Both three provide resonable explanations. The two-component jet model and the energy injection model imply a relatively small initial energy and velocity of the jet in the line of sight, while the forward-reverse shock model remains typical. Under the two-component jet model, EP240801a may resemble GRB 221009A (BOAT) if the bright narrow beam is viewed on-axis. Therefore, EP240801a can be interpreted as an off-beam (narrow) jet or an intrinsically weak GRB jet. Our findings provide crucial clues for uncovering the origin of XRFs. Copyright © 2025, The Authors. All rights reserved.

关键词： Gamma rays

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Photometric Investigation of the Contact Binary GU Ori with High Metallicity

arXiv

引用

arXiv 2018年

作者： Zhou, X. Qian, S.-B. Soonthornthum, B. Poshyachinda, S. Zhu, L.-Y. Liu, N.-P. Sarotsakulchai, T. Fang, X.-H. P.O. Box 110 Kunming650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences P. O. Box 110 Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Road Chaoyang Dis-trict Beijing100012 China University of the Chinese Academy of Sciences Yuquan Road 19# Sijingshang Block Beijing100049 China National Astronomical Research Institute of Thailand 260 Moo 4 T. Donkaew A. MaerimChiangmai50180 Thailand

GU Ori was observed with the 1m telescope at Yunnan Observatories in 2005. To determine its physical properties, the Wilson-Devinney program is used. The results reveal that GU Ori is a W-subtype shallow contact binary with a more massive but cooler star 2. The mass of its two component stars are estimated to be M1 = 0.45M☉, M2 = 1.05M☉. The O’Connell effect was reported to be negative on the light curves observed in 2005. However, it changed to a positive one on the light curves observed from 2011 to 2012. The mean surface temperatures of star 2 (T2) determined by the two sets of light curves were different, which may result from stellar activities. The O - C diagram shows that the period of GU Ori is decreasing at a rate of dP/dt = −6.24 × 10−8day · year−1, which may be caused by mass transfer from star 2 to star 1 with a rate of dMdt2 = −2.98 × 10−8M☉/year. GU Ori is a contact binary with quite high metallicity. Copyright © 2018, The Authors. All rights reserved.

关键词： Photometry

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Massive stars, successes and challenges

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Proceedings of the International Astronomical Union 2016年第S329期12卷 3-14页

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 Guiyang Guizhou Province 550025 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 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 © International Astronomical Union 2017.

关键词： convection magnetic field mass loss Massive stars multiplicity rotation

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TY Pup: a low-mass-ratio and deep contact binary as a progenitor candidate of luminous red novae

arXiv

引用

arXiv 2018年

作者： Sarotsakulchai, T. Qian, S.-B. Soonthornthum, B. Zhou, X. Zhang, J. Reichart, D.E. Haislip, J.B. Kouprianov, V.V. Poshyachinda, S. Yunnan Observatories Chinese Academy of Sciences Kunming650216 China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650216 China Center for Astronomical Mega-Science Chinese Academy of Sciences 20A Datun Rd. Chaoyang District Beijing100012 China University of Chinese Academy of Sciences 19 A Yuquan Rd. Shijingshan Beijing100049 China National Astronomical Research Institute of Thailand Ministry of Science and Technology Bangkok Thailand Department of Physics and Astronomy University of North Carolina CB #3255 Chapel HillNC27599 United States

TY Pup is a well-known bright eclipsing binary with an orbital period of 0.8192 days. New light curves in B, V, (RI)C bands were obtained with the 0.61-m reflector robotic telescope (PROMPT-8) at CTIO in Chile during 2015 and 2017. By analysing those photometric data with the W-D method, it is found that TY Pup is a low-mass-ratio (q ∼ 0.184) and deep contact binary with a high fill-out factor (84.3 %). An investigation of all available times of minimum light including three new ones obtained with the 60-cm and the 1.0-m telescopes at Yunnan Observatories in China indicates that the period change of TY Pup is complex. An upward parabolic variation in the O − C diagram is detected to be superimposed on a cyclic oscillation. The upward parabolic change reveals a long-term continuous increase in the orbital period at a rate of dP/dt = 5.57(±0.08) × 10−8 d yr−1. The period increase can be explained by mass transfer from the less massive component (M2 ∼ 0.3M☉) to the more massive one (M1 ∼ 1.65M☉). The binary will be merging when it meets the criterion that the orbital angular momentum is less than 3 times the total spin angular momentum, i.e., Jorb rot. This suggests that the system will finally merge into a rapid-rotating single star and may produce a luminous red nova. The cyclic oscillation in the O − C diagram can be interpreted by the light-travel time effect (LITE) via the presence of a third body. Copyright © 2018, The Authors. All rights reserved.

关键词： Stars

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The Fermi-LAT Light Curve Repository

arXiv

引用

arXiv 2023年

作者： Abdollahi, S. Ajello, M. Baldini, L. Ballet, J. Bastieri, D. Gonzalez, J. Becerra Bellazzini, R. Berretta, A. Bissaldi, E. Bonino, R. Brill, A. Bruel, P. Burns, E. Buson, S. Cameron, R.A. Caputo, R. Caraveo, P.A. Cibrario, N. Ciprini, S. Orestano, P. Cristarella Crnogorcevic, M. Cutini, S. D’Ammando, F. De Gaetano, S. Digel, S.W. Di Lalla, N. Di Venere, L. Domínguez, A. Ramazani, V. Fallah Fegan, S.J. Ferrara, E.C. Fiori, A. Fleischhack, H. Franckowiak, A. Fukazawa, Y. Fusco, P. Gammaldi, V. Gargano, F. Garrappa, S. Gasbarra, C. Gasparrini, D. Giglietto, N. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guiriec, S. Gustafsson, M. Hays, E. Horan, D. Hou, X. Jóhannesson, G. Kerr, M. Kocevski, D. Kuss, M. Latronico, L. Li, J. Liodakis, I. Longo, F. Loparco, F. Lorusso, L. Lott, B. Lovellette, M.N. Lubrano, P. Maldera, S. Manfreda, A. Martí-Devesa, G. Mazziotta, M.N. Mereu, I. Meyer, M. Michelson, P.F. Mizuno, T. Monzani, M.E. Morselli, A. Moskalenko, I.V. Negro, M. Omodei, N. Orlando, E. Ormes, J.F. Paneque, D. Panzarini, G. Perkins, J.S. Persic, M. Pesce-Rollins, M. Pillera, R. Porter, T.A. Principe, G. Racusin, J.L. Rainò, S. Rando, R. Rani, B. Razzano, M. Razzaque, S. Reimer, A. Reimer, O. Sánchez-Conde, M. Parkinson, P.M. Saz Scargle, Jeff Scotton, L. Serini, D. Sgrò, C. Siskind, E.J. Spandre, G. Spinelli, P. Suson, D.J. Tajima, H. Thompson, D.J. Torres, D.F. Valverde, J. Venters, T. Wadiasingh, Z. Wagner, S. Wood, K. IRAP Université de Toulouse CNRS UPS CNES ToulouseF-31028 France 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 Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova Via F. Marzolo 8 PadovaI-35131 Italy Center for Space Studies and Activities "G. Colombo" University of Padova Via Venezia 15 PadovaI-35131 Italy Instituto de Astrofísica de Canarias Observatorio del Teide C/Via Lactea s/n Tenerife La LagunaE-38205 Spain Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Dipartimento di Fisica Università degli Studi di Perugia PerugiaI-06123 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 Bari 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 NASA Postdoctoral Program Fellow United States NASA Goddard Space Flight Center GreenbeltMD20771 United States Laboratoire Leprince-Ringuet CNRS IN2P3 École polytechnique Institut Polytechnique de Paris Palaiseau91120 France Department of physics and Astronomy Louisiana State University Baton RougeLA70803 United States Institut für Theoretische Physik and Astrophysik Universität Würzburg WürzburgD-97074 Germany 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. Bassi

The Fermi Large Area Telescope (LAT) light curve repository (LCR) is a publicly available, continually updated library of gamma-ray light curves of variable Fermi-LAT sources generated over multiple timescales. The Fermi-LAT LCR aims to provide publication-quality light curves binned on timescales of 3 days, 7 days, and 30 days for 1525 sources deemed variable in the source catalog of the first 10 years of Fermi-LAT observations. The repository consists of light curves generated through full likelihood analyses that model the sources and the surrounding region, providing fluxes and photon indices for each time bin. The LCR is intended as a resource for the time-domain and multi-messenger communities by allowing users to quickly search LAT data to identify correlated variability and flaring emission episodes from gamma-ray sources. We describe the sample selection and analysis employed by the LCR and provide an overview of the associated data access portal. Copyright © 2023, The Authors. All rights reserved.

关键词： Gamma rays

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A search for exoplanets around northern circumpolar stars. IV. Six planet candidates to the K giants, HD 44385, HD 97619, HD 106574, HD 118904, HD 164428, and HD 202432

arXiv

引用

arXiv 2018年

作者： Jeong, Gwanghui Han, Inwoo Park, Myeong-Gu Hatzes, Artie P. Bang, Tae-Yang Gu, Shenghong Bai, Jinming Lee, Byeong-Cheol Korea Astronomy and Space Science Institute 776 Daedeokdae-Ro Youseong-Gu Daejeon34055 Korea Republic of Korea University of Science and Technology 217 Gajeong-ro Yuseong-gu Daejeon34113 Korea Republic of Department of Astronomy and Atmospheric Sciences Kyungpook National University Daegu41566 Korea Republic of Thüringer Landessternwarte Tautenburg Sternwarte 5 TautenburgD-07778 Germany Yunnan Observatories Chinese Academy of Sciences Kunming650216 China University of Chinese Academy of Sciences Beijing100049 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming650011 China

We report the discovery of long-period radial velocity (RV) variations in six intermediate mass K giant stars using precise RV measurements. These discoveries are part of the Search for Exoplanets around Northern Circumpolar Stars (SENS) survey being conducted at the Bohyunsan Optical Astronomy Observatory (BOAO). The nature of the RV variations was investigated by looking for photometric and line shape variations. We can find no variability with the RV period in these quantities and conclude that RV variations are most likely due to unseen sub-stellar companions. Orbital solutions for the six stars yield orbital periods in the range 418 - 1065 d and minimum masses in the range 1.9 - 8.5 MJ. These properties are typical on planets around intermediate mass stars. Our SENS survey so far has about an 8% confirmed planet occurrence rate, and it will provide better statistics on planets around giant stars when the survey is completed. Copyright © 2018, The Authors. All rights reserved.

关键词： Extrasolar planets

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