Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published November 30, 2023 | Published
Journal Article Open

Minutes-duration optical flares with supernova luminosities


In recent years, certain luminous extragalactic optical transients have been observed to last only a few days1. Their short observed duration implies a different powering mechanism from the most common luminous extragalactic transients (supernovae), whose timescale is weeks2. Some short-duration transients, most notably AT2018cow (ref. 3), show blue optical colours and bright radio and X-ray emission4. Several AT2018cow-like transients have shown hints of a long-lived embedded energy source5, such as X-ray variability6,7, prolonged ultraviolet emission8, a tentative X-ray quasiperiodic oscillation9,10 and large energies coupled to fast (but subrelativistic) radio-emitting ejecta11,12. Here we report observations of minutes-duration optical flares in the aftermath of an AT2018cow-like transient, AT2022tsd (the 'Tasmanian Devil'). The flares occur over a period of months, are highly energetic and are probably nonthermal, implying that they arise from a near-relativistic outflow or jet. Our observations confirm that, in some AT2018cow-like transients, the embedded energy source is a compact object, either a magnetar or an accreting black hole.

Copyright and License

© 2023 The Author(s), under an exclusive license to Springer Nature.


A.Y.Q.H. would like to thank E. Quataert, D. Lai, J. Cordes and E. S. Phinney for discussions on the physical origin of AT2022tsd and its flares; S. Chatterjee and D. Dong for advice on VLA calibration and imaging; B. Cenko for assistance with Swift observations; M. Brightman and B. Cenko for assistance with Chandra data reduction; K. Ward-Duong, K. Follette, S. Betti, J. Louison, J. Zhang, R. Margutti and R. Chornock for assistance with Keck ToO observations; I. Yoon for advice on ALMA calibration and imaging; and A. Miller for discussions about optical time-series analysis. P. Chen would like to thank Y. Beletsky for his assistance in remote observations with the Magellan telescope. S. Schulze acknowledges support from the G.R.E.A.T. research environment, funded by Vetenskapsrådet, the Swedish Research Council, project number 2016-06012. VSD, ULTRASPEC and ULTRACAM are funded by the UK's Science and Technology Facilities Council (STFC), grant ST/V000853/1. S.J.S. acknowledges funding from STFC grants ST/T000198/1 and ST/S006109/1. This work was funded by ANID, Millennium Science Initiative, ICN12_009. We thank Lulin staff H.-Y. Hsiao, C.-S. Lin, W.-J. Hou, H.-C. Lin and J.-K. Guo for observations and data management. M.W.C. acknowledges support from the US National Science Foundation (NSF) with grants PHY-2010970 and OAC-2117997. L.G., C.P.G. and T.E.M.-B. acknowledge financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN), the Agencia Estatal de Investigación (AEI) 10.13039/501100011033, the European Social Fund (ESF) 'Investing in Your Future', the European Union Next Generation EU/PRTR funds, the Horizon 2020 Research and Innovation programme of the European Union and by the Secretary of Universities and Research (Government of Catalonia), under the PID2020-115253GA-I00 HOSTFLOWS project, the 2019 Ramón y Cajal programme RYC2019-027683-I, the 2021 Juan de la Cierva programme FJC2021-047124-I, the Marie Skłodowska-Curie and the Beatriu de Pinós 2021 BP 00168 programme and from Consejo Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016 and the programme Unidad de Excelencia María de Maeztu CEX2020-001058-M. A.G.-Y.'s research is supported by the EU through European Research Council (ERC) grant 725161, the ISF GW excellence centre, an IMOS space infrastructure grant, a GIF grant, as well as the André Deloro Institute for Advanced Research in Space and Optics, the Helen Kimmel Center for Planetary Science, the Schwartz/Reisman Collaborative Science Program and the Norman E. Alexander Family M Foundation ULTRASAT Data Center Fund, Minerva and Yeda-Sela; A.G.-Y. is the incumbent of the Arlyn Imberman Professorial Chair. N.A.J. would like to acknowledge the DST-INSPIRE Faculty Fellowship (IFA20-PH-259) for supporting this research. C.-C.N. is grateful for funding from the Ministry of Science and Technology (Taiwan) under contract 109-2112-M-008-014-MY3. M.N. is supported by the ERC under the EU's Horizon 2020 Research and Innovation programme (grant agreement no. 948381) and by funding from the UK Space Agency. E.O.O. acknowledges grants from the ISF, IMOS and BSF. F.O. acknowledges support from MIUR, PRIN 2017 (grant 20179ZF5KS) 'The new frontier of the Multi-Messenger Astrophysics: follow-up of electromagnetic transient counterparts of gravitational wave sources'. D.P. is grateful to the LAST Observatory staff. M.P. is supported by a research grant (19054) from VILLUM FONDEN. A.V.F.'s group at U.C. Berkeley received financial support from the Christopher R. Redlich Fund, G. and C. Bengier, A. Eustace, S. Robertson, C. and S. Winslow, B. and K. Wood and many other donors. The work of D.S. was carried out in the framework of the basic funding programme of the Ioffe Institute no. 0040-2019-0025. Based in part on observations obtained with the 48-inch Samuel Oschin Telescope and the 60-inch telescope at Palomar Observatory as part of the ZTF project. The ZTF is supported by NSF grants AST-1440341 and AST-2034437 and a collaboration including current partners Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Northwestern University and former partners the University of Washington, Los Alamos National Laboratories and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC and UW. The ZTF forced-photometry service was funded under Heising-Simons Foundation grant no. 12540303 (PI: M. Graham). The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawai'i, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, the Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute (STScI), the National Aeronautics and Space Administration (NASA) under grant NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, NSF grant AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory and the Gordon and Betty Moore Foundation. This work has made use of data from the ATLAS project. The ATLAS project is primarily funded to search for near-Earth objects through NASA grants NN12AR55G, 80NSSC18K0284 and 80NSSC18K1575; by-products of the near-Earth object search include images and catalogues from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889 and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawai'i Institute for Astronomy, the Queen's University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory and the Millennium Institute of Astrophysics (MAS), Chile. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK STFC. Based in part on observations made with ULTRASPEC at the Thai National Observatory, which is operated by the National Astronomical Research Institute of Thailand (public organization). Based in part on observations obtained with the SEDM on the Kitt Peak 84-inch telescope (SEDM-KP). The SEDM-KP team thanks the NSF and the National Optical-Infrared Astronomy Research Laboratory for making the Kitt Peak 2.1-m telescope available. SEDM-KP is supported by the Heising Simons Foundation under grant 2021-2612 titled 'The SEDM Kitt Peak Project' and a collaboration including current partners Caltech, University of Minnesota, the University of Maryland, Northwestern University and STScI. This work made use of data from the GROWTH-India Telescope (GIT) set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB). It is located at the Indian Astronomical Observatory (Hanle), operated by the IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports operations of the telescope. Telescope technical details are available online186. We thank the staff of the Indian Astronomical Observatory (IAO), Hanle and CREST, Hosakote, that made these observations possible. The facilities at the IAO and CREST are operated by the IIA, Bangalore. This paper includes data gathered with the 6.5-m Magellan Telescopes located at Las Campanas Observatory, Chile. On the basis of observations made with the Nordic Optical Telescope, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku and the University of Oslo, representing Denmark, Finland and Norway, respectively, the University of Iceland and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. This publication has made use of data collected at Lulin Observatory, partly supported by MoST grant 108-2112-M-008-001. Based partially on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, as part of ePESSTO+ (the advanced Public ESO Spectroscopic Survey for Transient Objects Survey). ePESSTO+ observations were obtained under ESO programme 108.220C (PI: Inserra). Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We wish to recognize and acknowledge the substantial cultural role and reverence that the summit of Maunakea has always had within the Indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. The Giant Metrewave Radio Telescope (GMRT) is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2022.A.00010.T. ALMA is a partnership of the ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by the ESO, AUI/NRAO and NAOJ. The National Radio Astronomy Observatory is a facility of the NSF operated under cooperative agreement by Associated Universities, Inc. Based in part on observations carried out with the IRAM Interferometer NOEMA. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. The scientific results reported in this article are based in part on observations made by the Chandra X-ray Observatory. This research has made use of software provided by the Chandra X-ray Center (CXC) in the application packages CIAO and Sherpa.


All authors reviewed the manuscript and contributed to the source interpretation. A.Y.Q.H. identified the source; coordinated the follow-up observations; performed radio, X-ray and some optical data analysis; performed the source analysis and modelling; and wrote most of the manuscript. D.A.P. performed the optical image subtraction and photometry and contributed notably to the follow-up campaign, the source analysis and the manuscript. P. Chen observed the source with Magellan and LAST, made the first flare identification and assisted with follow-up observations and X-ray data analysis. S. Schulze performed the host-galaxy analysis, assisted with Swift data analysis and performed follow-up observations with the NOT. V.D. provided follow-up observations with ULTRACAM and ULTRASPEC. H.K., V.S., A.S. and V.B. performed follow-up observations and image reduction with the GIT and the HCT. M.B. performed NOEMA follow-up observations and data reduction. S.J.S. provided ATLAS and Pan-STARRS photometry. J.P.A., C.P.G., L.G., M.G., C.I., T.E.M.-B., F.O., M.P., P.J.P., P.W., Y.W. and D.R.Y. are ePESSTO+ builders. G.C.A. and S.B. are GIT builders. S.A. and S.P. enabled NARIT/Thai National Telescope observations. E.C.B., R.B., M.W.C., A.J.D., M.G., A.A.M., B.R., R.R. and A.W. are ZTF builders. S.B., D.P., E.S. and N.L.S. are LAST builders. T.d.B., M.D.F., H.G., E.A.M., M.N., K.W.S. and S.S. assisted with Pan-STARRS data analysis. T.G.B., J.C., C.F., J.F., S.K., M.M.K., V.K. and M.S. assisted with Keck follow-up observations. N.A.J. and P.C. performed uGMRT follow-up observations and data analysis. T.-W.C., W.-P.C., C.-C.N., Y.-C.P. and S.Y. assisted with Lulin observations and data reduction. K.K.D. observed with the P200. A.V.F. assisted with Keck follow-up observations and thoroughly reviewed the manuscript. A.G.-Y. assisted with LAST follow-up observations. K.-R.H. assisted with LT follow-up observations. T.M. contributed to Pan-STARRS and ePESSTO+ data analysis. E.O.O. assisted with LAST follow-up observations and performed LAST data reduction and photometry. C.M.B.O. contributed to the source analysis. G.P. performed SMA follow-up observations and data analysis. A.C.R. performed CHIMERA observations and data reduction. R.R. created the SEDM2 robotic observing software. Y.S. performed KP84 observations. J.S. assisted with NOT follow-up observations. D.S. performed the GRB search. Y.Y. helped write the transient scanning code and assisted with X-ray observations.

Data Availability

The reduced optical photometric data of AT2022tsd are provided in Supplementary Tables 1 and 2. Spectroscopy of AT2022tsd will be made available through the WISeREP public database. Facilities that make all their data available in public archives, either promptly or after a proprietary period, include the VLA, the LT, the W. M. Keck Observatory, the Palomar 48-inch/ZTF, the Neil Gehrels Swift Observatory, Chandra and ALMA. Furthermore, all of the data required to reproduce the figures are available in a public GitHub repository (www.github.com/annayqho/AT2022tsd).

Code Availability

The code used to perform the calculations and produce the figures for this paper is available in a public GitHub repository (www.github.com/annayqho/AT2022tsd).

Conflict of Interest

The authors declare no competing interests.


Files (2.3 MB)
Name Size Download all
52.4 kB Preview Download
14.8 kB Preview Download
198.8 kB Preview Download
336.2 kB Preview Download
27.7 kB Preview Download
228.9 kB Preview Download
694.2 kB Preview Download
252.4 kB Preview Download
102.3 kB Preview Download
10.5 kB Preview Download
251.0 kB Preview Download
71.7 kB Preview Download
47.1 kB Preview Download

Additional details

November 16, 2023
February 1, 2024