The Astrophysical Journal Letters (Jan 2025)
EP240801a/XRF 240801B: An X-Ray Flash Detected by the Einstein Probe and the Implications of Its Multiband Afterglow
- Shuai-Qing Jiang,
- Dong Xu,
- Agnes P. C. van Hoof,
- Wei-Hua Lei,
- Yuan Liu,
- Hao Zhou,
- Yong Chen,
- Shao-Yu Fu,
- Jun Yang,
- Xing Liu,
- Zi-Pei Zhu,
- Alexei V. Filippenko,
- Peter G. Jonker,
- A. S. Pozanenko,
- He Gao,
- Xue-Feng Wu,
- Bing Zhang,
- Gavin P Lamb,
- Massimiliano De Pasquale,
- Shiho Kobayashi,
- Franz Erik Bauer,
- Hui Sun,
- Giovanna Pugliese,
- Jie An,
- Valerio D’Elia,
- Johan P. U. Fynbo,
- WeiKang Zheng,
- Alberto J. Castro-Tirado,
- Yi-Han Iris Yin,
- Yuan-Chuan Zou,
- Adam T. Deller,
- N. S. Pankov,
- A. A. Volnova,
- A. S. Moskvitin,
- O. I. Spiridonova,
- D. V. Oparin,
- V. Rumyantsev,
- O. A. Burkhonov,
- Sh. A. Egamberdiyev,
- V. Kim,
- M. Krugov,
- A. M. Tatarnikov,
- R. Inasaridze,
- Andrew J. Levan,
- Daniele Bjørn Malesani,
- Maria E. Ravasio,
- Jonathan Quirola-Vásquez,
- Joyce N. D. van Dalen,
- Javi Sánchez-Sierras,
- Daniel Mata Sánchez,
- Stuart P. Littlefair,
- Jennifer A. Chacón,
- Manuel A. P. Torres,
- Ashley A. Chrimes,
- Nikhil Sarin,
- Antonio Martin-Carrillo,
- Vik Dhillon,
- Yi Yang,
- Thomas G. Brink,
- Rebecca L. Davies,
- Sheng Yang,
- Amar Aryan,
- Ting-Wan Chen,
- Albert K. H. Kong,
- Wen-Xiong Li,
- Rui-Zhi Li,
- Jirong Mao,
- Ignacio Pérez-García,
- Emilio J. Fernández-García,
- Moira Andrews,
- Joseph Farah,
- Zhou Fan,
- Estefania Padilla Gonzalez,
- D. Andrew Howell,
- Dieter Hartmann,
- Jing-Wei Hu,
- Páll Jakobsson,
- Cheng-Kui Li,
- Zhi-Xing Ling,
- Curtis McCully,
- Megan Newsome,
- Benjamin Schneider,
- Kaew Samaporn Tinyanont,
- Ning-Chen Sun,
- Giacomo Terreran,
- Qing-Wen Tang,
- Wen-Xin Wang,
- Jing-Jing Xu,
- Wei-Min Yuan,
- Bin-Bin Zhang,
- Hai-Sheng Zhao,
- Juan Zhang
Affiliations
- Shuai-Qing Jiang
- ORCiD
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Dong Xu
- ORCiD
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]; Altay Astronomical Observatory , Altay, Xinjiang 836500, People’s Republic of China
- Agnes P. C. van Hoof
- ORCiD
- Radboud University Nijmegen , Department of Astrophysics/IMAPP, P.O. Box 9010, Nijmegen, 6500 GL, The Netherlands
- Wei-Hua Lei
- ORCiD
- Department of Astronomy, School of Physics, Huazhong University of Science and Technology , Wuhan, 430074, People’s Republic of China ; [email protected]
- Yuan Liu
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]
- Hao Zhou
- ORCiD
- Purple Mountain Observatory , Chinese Academy of Sciences, Nanjing 210023, People’s Republic of China
- Yong Chen
- ORCiD
- Key Laboratory of Particle Astrophysics , Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Shao-Yu Fu
- ORCiD
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]
- Jun Yang
- ORCiD
- School of Astronomy and Space Science, Nanjing University , Nanjing 210093, People’s Republic of China; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, People’s Republic of China
- Xing Liu
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Zi-Pei Zhu
- ORCiD
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]
- Alexei V. Filippenko
- ORCiD
- Department of Astronomy, University of California , Berkeley, CA 94720-3411, USA
- Peter G. Jonker
- ORCiD
- Radboud University Nijmegen , Department of Astrophysics/IMAPP, P.O. Box 9010, Nijmegen, 6500 GL, The Netherlands
- A. S. Pozanenko
- ORCiD
- Space Research Institute , Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow, 117997, Russia; National Research University “Higher School of Economics , ” Myasnitskaya ul. 20, Moscow, 101000, Russia; Moscow Institute of Physics and Technology (MIPT) , Institutskiy Pereulok, 9, Dolgoprudny, 141701, Russia
- He Gao
- ORCiD
- School of Physics and Astronomy, Beijing Normal University , Beijing 100875, People’s Republic of China; Institute for Frontier in Astronomy and Astrophysics, Beijing Normal University , Beijing 102206, People’s Republic of China
- Xue-Feng Wu
- ORCiD
- Purple Mountain Observatory , Chinese Academy of Sciences, Nanjing 210023, People’s Republic of China
- Bing Zhang
- ORCiD
- Nevada Center for Astrophysics, University of Nevada Las Vegas , NV 89154, USA; Department of Physics and Astronomy, University of Nevada Las Vegas , NV 89154, USA
- Gavin P Lamb
- ORCiD
- Astrophysics Research Institute, Liverpool John Moores University , IC2 Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
- Massimiliano De Pasquale
- ORCiD
- University of Messina , MIFT Department, Via F.S. D’Alcontres 31, Messina, 98166, Italy
- Shiho Kobayashi
- ORCiD
- Astrophysics Research Institute, Liverpool John Moores University , IC2 Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF, UK
- Franz Erik Bauer
- ORCiD
- Instituto de Alta Investigación , Universidad de Tarapacá, Casilla 7D, Arica, Chile
- Hui Sun
- ORCiD
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]
- Giovanna Pugliese
- ORCiD
- Anton Pannekoek Institute of Astronomy, University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands
- Jie An
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Valerio D’Elia
- ORCiD
- Space Science Data Center (SSDC)—Agenzia Spaziale Italiana (ASI) , I-00133 Roma, Italy; Osservatorio Astronomico di Roma , via Frascati 33, I-00040 Monte Porzio Catone, Italy
- Johan P. U. Fynbo
- ORCiD
- The Cosmic Dawn Centre (DAWN) , Denmark; Niels Bohr Institute, University of Copenhagen , Jagtvej 155, DK-2200, Copenhagen N, Denmark
- WeiKang Zheng
- ORCiD
- Department of Astronomy, University of California , Berkeley, CA 94720-3411, USA
- Alberto J. Castro-Tirado
- ORCiD
- Instituto de Astrofísica de Andalucía (IAA-CSIC) , Glorieta de la Astronomía s/n, 18008 Granada, Spain; Ingeniería de Sistemas y Automática, Universidad de Málaga , Unidad Asociada al CSIC por el IAA, Escuela de Ingenierías Industriales, Arquitecto Francisco Peñalosa, 6, Campanillas, 29071 Málaga, Spain
- Yi-Han Iris Yin
- ORCiD
- School of Astronomy and Space Science, Nanjing University , Nanjing 210093, People’s Republic of China; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, People’s Republic of China
- Yuan-Chuan Zou
- ORCiD
- Department of Astronomy, School of Physics, Huazhong University of Science and Technology , Wuhan, 430074, People’s Republic of China ; [email protected]
- Adam T. Deller
- ORCiD
- Center for Astrophysics and Supercomputing, Swinburne University of Technology , P.O. Box 218, Hawthorn, VIC 3122, Australia; ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) , Hawthorn, VIC 3122, Australia
- N. S. Pankov
- Space Research Institute , Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow, 117997, Russia; National Research University “Higher School of Economics , ” Myasnitskaya ul. 20, Moscow, 101000, Russia
- A. A. Volnova
- Space Research Institute , Russian Academy of Sciences, Profsoyuznaya ul. 84/32, Moscow, 117997, Russia
- A. S. Moskvitin
- ORCiD
- Special Astrophysical Observatory of the Russian Academy of Sciences , Nizhny Arkhyz 369167, Russia
- O. I. Spiridonova
- Special Astrophysical Observatory of the Russian Academy of Sciences , Nizhny Arkhyz 369167, Russia
- D. V. Oparin
- Special Astrophysical Observatory of the Russian Academy of Sciences , Nizhny Arkhyz 369167, Russia
- V. Rumyantsev
- Crimean Astrophysical Observatory , 298409, Nauchny, Crimea†
- O. A. Burkhonov
- Ulugh Beg Astronomical Institute , Uzbek Academy of Sciences, Tashkent, Uzbekistan
- Sh. A. Egamberdiyev
- ORCiD
- Ulugh Beg Astronomical Institute , Uzbek Academy of Sciences, Tashkent, Uzbekistan; National University of Uzbekistan , Tashkent, Uzbekistan
- V. Kim
- Fesenkov Astrophysical Institute , Almaty, 050020, Kazakhstan
- M. Krugov
- Fesenkov Astrophysical Institute , Almaty, 050020, Kazakhstan
- A. M. Tatarnikov
- Sternberg Astronomical Institute, Lomonosov Moscow State University , Moscow, 119191, Russia
- R. Inasaridze
- Evgeni Kharadze Georgian National Astrophysical Observatory , 0301, Adigeni, Abastumani, Mt. Kanobili, Georgia; Samtskhe-Javakheti State University , Rustaveli Str. 113, Akhaltsikhe, 0080, Georgia
- Andrew J. Levan
- ORCiD
- Radboud University Nijmegen , Department of Astrophysics/IMAPP, P.O. Box 9010, Nijmegen, 6500 GL, The Netherlands; University of Warwick , Department of Physics, Coventry, CV4 7AL, UK
- Daniele Bjørn Malesani
- ORCiD
- The Cosmic Dawn Centre (DAWN) , Denmark; Niels Bohr Institute, University of Copenhagen , Jagtvej 155, DK-2200, Copenhagen N, Denmark
- Maria E. Ravasio
- ORCiD
- Radboud University Nijmegen , Department of Astrophysics/IMAPP, P.O. Box 9010, Nijmegen, 6500 GL, The Netherlands; Osservatorio Astronomico di Brera , Istituto Nazionale di Astrofisica, Merate 23807, Italy
- Jonathan Quirola-Vásquez
- ORCiD
- Radboud University Nijmegen , Department of Astrophysics/IMAPP, P.O. Box 9010, Nijmegen, 6500 GL, The Netherlands
- Joyce N. D. van Dalen
- ORCiD
- Radboud University Nijmegen , Department of Astrophysics/IMAPP, P.O. Box 9010, Nijmegen, 6500 GL, The Netherlands
- Javi Sánchez-Sierras
- ORCiD
- Radboud University Nijmegen , Department of Astrophysics/IMAPP, P.O. Box 9010, Nijmegen, 6500 GL, The Netherlands
- Daniel Mata Sánchez
- ORCiD
- Instituto de Astrofísica de Canarias , E-38205, La Laguna, Tenerife, Spain; Universidad de La Laguna , Departamento de Astroísica, E-38206, La Laguna, Tenerife, Spain
- Stuart P. Littlefair
- ORCiD
- University of Sheffield , Department of Physics and Astronomy, Sheffield, S3 7RH, UK
- Jennifer A. Chacón
- ORCiD
- Instituto de Astrofísica , Facultad de Física, Pontificia Universidad Católica de Chile, Campus San Joaquín, Av. Vicuña Mackenna 4860, Macul Santiago, 7820436, Chile; Millennium Institute of Astrophysics , Nuncio Monseñor Sótero Sanz 100, Of 104, Providencia, Santiago, Chile
- Manuel A. P. Torres
- ORCiD
- Instituto de Astrofísica de Canarias , E-38205, La Laguna, Tenerife, Spain; Universidad de La Laguna , Departamento de Astroísica, E-38206, La Laguna, Tenerife, Spain
- Ashley A. Chrimes
- ORCiD
- Radboud University Nijmegen , Department of Astrophysics/IMAPP, P.O. Box 9010, Nijmegen, 6500 GL, The Netherlands; European Space Agency (ESA) , European Space Research and Technology Centre (ESTEC), Keplerlaan 1, Noordwijk, 2201 AZ, The Netherlands
- Nikhil Sarin
- ORCiD
- The Oskar Klein Centre, Department of Physics, Stockholm University , AlbaNova, Stockholm, SE-106 91, Stockholm, Sweden; Nordita, Stockholm University and KTH Royal Institute of Technology , Hannes Alfvéns väg 12, Stockholm, SE-106 91, Stockholm, Sweden
- Antonio Martin-Carrillo
- ORCiD
- School of Physics and Centre for Space Research, University College Dublin , Dublin, D04 V1W8, Dublin, Ireland
- Vik Dhillon
- ORCiD
- University of Sheffield , Department of Physics and Astronomy, Sheffield, S3 7RH, UK
- Yi Yang
- ORCiD
- Physics Department, Tsinghua University , Beijing, 100084, People’s Republic of China
- Thomas G. Brink
- ORCiD
- Department of Astronomy, University of California , Berkeley, CA 94720-3411, USA
- Rebecca L. Davies
- ORCiD
- Center for Astrophysics and Supercomputing, Swinburne University of Technology , P.O. Box 218, Hawthorn, VIC 3122, Australia
- Sheng Yang
- ORCiD
- Institute for Gravitational Wave Astronomy , Henan Academy of Sciences, Zhengzhou 450046, Henan, People’s Republic of China
- Amar Aryan
- ORCiD
- Graduate Institute of Astronomy, National Central University , 300 Jhongda Road, 32001 Jhongli, Taiwan
- Ting-Wan Chen
- ORCiD
- Graduate Institute of Astronomy, National Central University , 300 Jhongda Road, 32001 Jhongli, Taiwan
- Albert K. H. Kong
- ORCiD
- Institute of Astronomy, National Tsing Hua University , No. 101 Sect. 2 Kuang-Fu Road, 30013 Hsinchu, Taiwan
- Wen-Xiong Li
- ORCiD
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]
- Rui-Zhi Li
- ORCiD
- School of Astronomy and Space Science, University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People’s Republic of China; Yunnan Observatories , Chinese Academy of Sciences, Kunming 650216, People’s Republic of China
- Jirong Mao
- ORCiD
- Yunnan Observatories , Chinese Academy of Sciences, Kunming 650216, People’s Republic of China; Center for Astronomical Mega-Science , Chinese Academy of Sciences, Beijing 100012, People’s Republic of China; Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences , Kunming 650216, People’s Republic of China
- Ignacio Pérez-García
- Instituto de Astrofísica de Andalucía (IAA-CSIC) , Glorieta de la Astronomía s/n, 18008 Granada, Spain
- Emilio J. Fernández-García
- Instituto de Astrofísica de Andalucía (IAA-CSIC) , Glorieta de la Astronomía s/n, 18008 Granada, Spain
- Moira Andrews
- Las Cumbres Observatory , 6740 Cortona Drive, Suite 102, Goleta, CA 93117-5575, USA
- Joseph Farah
- ORCiD
- Las Cumbres Observatory , 6740 Cortona Drive, Suite 102, Goleta, CA 93117-5575, USA; Department of Physics, University of California , Santa Barbara, CA 93106-9530, USA
- Zhou Fan
- ORCiD
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Estefania Padilla Gonzalez
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- D. Andrew Howell
- ORCiD
- Las Cumbres Observatory , 6740 Cortona Drive, Suite 102, Goleta, CA 93117-5575, USA; Department of Physics, University of California , Santa Barbara, CA 93106-9530, USA
- Dieter Hartmann
- ORCiD
- Department of Physics and Astronomy, Clemson University , Clemson, SC 29631, USA
- Jing-Wei Hu
- ORCiD
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]
- Páll Jakobsson
- ORCiD
- Center for Astrophysics and Cosmology, Science Institute, University of Iceland , Dunhagi 5, 107 Reykjavík, Iceland
- Cheng-Kui Li
- ORCiD
- Key Laboratory of Particle Astrophysics , Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Zhi-Xing Ling
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Curtis McCully
- ORCiD
- Las Cumbres Observatory , 6740 Cortona Drive, Suite 102, Goleta, CA 93117-5575, USA; Department of Physics, University of California , Santa Barbara, CA 93106-9530, USA
- Megan Newsome
- ORCiD
- Las Cumbres Observatory , 6740 Cortona Drive, Suite 102, Goleta, CA 93117-5575, USA; Department of Physics, University of California , Santa Barbara, CA 93106-9530, USA
- Benjamin Schneider
- ORCiD
- Massachusetts Institute of Technology , Kavli Institute for Astrophysics and Space Research, Cambridge, MA, USA; Aix Marseille Université , CNRS, CNES, LAM, Marseille, France
- Kaew Samaporn Tinyanont
- ORCiD
- National Astronomical Research Institute of Thailand , 260 Moo 4, T. Donkaew, A. Maerim, Chiangmai, 50180, Thailand
- Ning-Chen Sun
- ORCiD
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People’s Republic of China; Institute for Frontier in Astronomy and Astrophysics, Beijing Normal University , Beijing 102206, People’s Republic of China
- Giacomo Terreran
- ORCiD
- Adler Planetarium , 1300 South DuSable Lake Shore Drive, Chicago, IL 60605, USA
- Qing-Wen Tang
- ORCiD
- Department of Physics, School of Physics and Materials Science, Nanchang University , Nanchang 330031, People’s Republic of China
- Wen-Xin Wang
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]
- Jing-Jing Xu
- Key Laboratory of Particle Astrophysics , Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Wei-Min Yuan
- National Astronomical Observatories , Chinese Academy of Sciences, Beijing 100101, People’s Republic of China ; [email protected]; School of Astronomy and Space Science, University of Chinese Academy of Sciences , Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Bin-Bin Zhang
- ORCiD
- Purple Mountain Observatory , Chinese Academy of Sciences, Nanjing 210023, People’s Republic of China; School of Astronomy and Space Science, Nanjing University , Nanjing 210093, People’s Republic of China; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, People’s Republic of China
- Hai-Sheng Zhao
- Key Laboratory of Particle Astrophysics , Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- Juan Zhang
- ORCiD
- Key Laboratory of Particle Astrophysics , Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
- DOI
- https://doi.org/10.3847/2041-8213/addebf
- Journal volume & issue
-
Vol. 988,
no. 1
p. L34
Abstract
We present multiband observations and analysis of EP240801a, a low-energy, extremely soft gamma-ray burst (GRB) discovered on 2024 August 1 by the Einstein Probe (EP) satellite with a weak contemporaneous signal also detected by the Fermi Gamma-ray Burst Monitor (GBM). Optical spectroscopy of the afterglow, obtained by Gran Telescopio Canarias 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 that the gamma-ray signal arrived 8.3 s earlier than the X-rays. Joint spectral fitting of EP Wide-field X-ray Telescope and Fermi/GBM data yields an isotropic energy ${E}_{\gamma ,{\rm{iso}}}=(5.5{7}_{-0.50}^{+0.54})\times 1{0}^{51}\,{\rm{erg}}$ , a peak energy ${E}_{{\rm{peak}}}=14.9{0}_{-4.71}^{+7.08}\,{\rm{keV}}$ , and a fluence ratio S (25–50 keV)/ S $(50\,\unicode{x02013}\,100\,{\rm{keV}})=1.6{7}_{-0.46}^{+0.74}$ , 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 Follow-up X-ray Telescope observations suggest multiple components in the afterglow. Three models are considered: a two-component jet model, a forward-reverse shock model, and a forward shock model with energy injection. All three provide reasonable 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.
Keywords
