AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole
Perley DA, Ho AYQ, McGrath Z, Camilo M, Sevilla C, Chen P, Schroeder G, Govreen-Segal T, Bochenek A, Qin Y-J, Gillanders JH, Amend B, Anderson JP, Andreoni I, Aryan A, Bellm EC, Bloom JS, de Boer T, Carney J, Caiazzo I, Chambers KC, Charalampopoulos P, Chen T-W, Chen TX, Coughlin ER, Coughlin M, Dennefeld M, Dimitriadis G, Fremling C, Frostig D, Gal-Yam A, Galbany L, Gangopadhyay A, Ghendrih M, Graham MJ, Gromadzki M, Groom SL, Gutiérrez CP, Hinds K-R, Huber ME, Inserra C, Kaiser BC, Kasliwal MM, Koivisto NE, Lin C-C, Liu C, Lowe TB, Magnier E, Mahabal AA, Milligan A, Minguez P, Mo G, Müller-Bravo TE, Nicholl M, Pessi PJ, Pignata G, Purdum J, Rehemtulla N, Rich RM, Sahu A, Singh A, Smartt SJ, Smith IA, Sollerman J, Srinivasaragavan G, Srivastav S, Stein RD, Schulze S, Tweddle JW, Wainscoat R, Wise JL, Yan L, Young DR. 2026. AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole. Monthly Notices of the Royal Astronomical Society. 549(1), stag678.
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Author
Perley, Daniel A;
Ho, Anna Y Q;
McGrath, Zoë;
Camilo, Michael;
Sevilla, Cassie;
Chen, Ping;
Schroeder, Genevieve;
Govreen-Segal, Taya;
Bochenek, Aleksandra;
Qin, Yu-Jing;
Gillanders, James H;
Amend, Benjamin
All
All
Department
Abstract
We present the discovery of AT 2024wpp (‘Whippet’), a fast and luminous 18cow-like transient. At a redshift of z = 0 . 0868 , revealed by Keck Cosmic Web Imager spectroscopy of its faint star-forming host, it is the fourth-nearest example of its class to date. Rapid identification of the source in the Zwicky Transient Facility data stream permitted ultraviolet-through- optical observations to be obtained prior to peak, allowing the first determination of the peak bolometric luminosity ( 2 ×1045 erg s−1 ), maximum photospheric radius ( 1015 cm), and total radiated energy ( 1051 erg) of an 18cow-like object. We present results from a comprehensive multiwavelength observing campaign, including a far-ultraviolet spectrum from the Cosmic Origins Spectrograph on the Hubble Space Telescope and deep imaging extending > 100 d post-explosion from the Very Large Telescope, Hubble Space Telescope , Very Large Array, and Atacama Large Millimetre Array. We interpret the observations under a model in which a rapidly accreting central engine blows a fast ( ∼0.2 c ) wind into the surrounding medium and irradiates it with X-rays. The high Doppler velocities and intense ionization within this wind prevent identifiable spectroscopic features from appearing in the ejecta or in the surrounding circumstellar material. Weak H and He signatures do emerge in the spectra after 35 d in the form of double-peaked narrow lines. Each peak is individually narrow (full width δv ∼3000 km s−1 ) but the two components are separated by v ∼6600 km s−1 , indicating stable structures of denser material, possibly representing streams of tidal ejecta or an ablated companion star.
Publishing Year
Date Published
2026-06-01
Journal Title
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press
Acknowledgement
We thank Eliot Quataert, Luc Dessart, Ben Margalit, Ross Ferguson, Aaron Tohuvavohu, Brad Cenko, and Jamie Kennea for useful discussions. We thank the referee for helpful suggestions that improved the manuscript.
Based on observations obtained with the Samuel Oschin Telescope 48-in. and the 60-in. Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under grant no. AST-2034437 and a collaboration including Caltech, IPAC, the Oskar Klein Center at Stockholm University, the University of Maryland, University of California, Berkeley, the University of Wisconsin at Milwaukee, University of Warwick, Ruhr University Bochum, Cornell University, Northwestern University and Drexel University. Operations are conducted by COO, IPAC, and UW.
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 Science and Technology Facilities Council.
Based on 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, 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. The NOT data were obtained under program ID 68–501.
This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. We are grateful to Phil Evans, Aaron Tohuvavohu, and Jamie Kennea for advice on the Swift/XRT data reduction.
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. The authors wish to recognize and acknowledge the very significant 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.
Some observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.
The National Radio Astronomy Observatory and Green Bank Observatory are facilities of the U.S. National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This paper makes use of the following ALMA data: ADS/JAO.ALMA no. 2023.1.01730.T ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSTC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ.
Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 2114.D-5014(E). We thank John Pritchard and Paula Sanchez Saez, and the entire observatory staff, for their excellent support.
Based 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 – PI: Inserra). ePESSTO+ observations were obtained under ESO program ID 112.25JQ.
This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. These observations are associated with programs 16714, 17477, and 17889.
Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia e Inovações (MCTI/LNA) do Brasil, the US National Science Foundation’s NOIRLab, the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).
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 Hawaii, 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, the National Aeronautics and Space Administration under grant no. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation grant no. AST–1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation.
This research made use of ccdproc, an astropy package for image reduction (M. Craig et al. 2025).
GS and AYQH acknowledge support in part from a Sloan Research Fellowship (award no. FG-2024-21320) from the Alfred P. Sloan Foundation. CS and AYQH acknowledge support in part from National Aeronautics and Space Administration (NASA) grant 80NSSC24K0377, from HST grant HST-GO-17477.006-A, and from a Scialog award from the Research Corporation for Science Advancement (‘Early Science with the LSST’).
PC acknowledges support from the Zhejiang Provincial Top-Level Research Support Program.
IA and JC are supported by the National Science Foundation award AST 2505775, NASA grant 24-ADAP24-0159, Scialog award SA-LSST-2024-102a, and the Discovery Alliance Catalyst Fellowship Mentors award 2025-62192-CM-19
AA acknowledges support from the Ministry of Education Yushan Fellow Program (MOE-111-YSFMS-0008-001-P1) and from the National Science and Technology Council, Taiwan (NSTC 114-2112-M-008-021-MY3).
T-WC acknowledges support from the Ministry of Education Yushan Fellow Program (MOE-111-YSFMS-0008-001-P1) and from the National Science and Technology Council, Taiwan (NSTC 114-2112-M-008-021-MY3).
ERC acknowledges support from the National Aeronautics and Space Administration through the Astrophysics Theory Program, grant 80NSSC24K0897.
GD acknowledges support from the European Union’s Horizon Europe research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 101199369.
DF’s contribution to this material is based upon work supported by the National Science Foundation under award no. AST-2401779.
AGY’s research is supported by ISF, IMOS, and BSF grants, as well as the André Deloro Institute for Space and Optics Research, the Center for Experimental Physics, a WIS-MIT Sagol grant, the Norman E Alexander Family M Foundation ULTRASAT Data Center Fund, and Yeda-Sela; AGY is the incumbent of the The Arlyn Imberman Professorial Chair.
LG acknowledges financial support from AGAUR, CSIC, MCIN, and AEI 10.13039/501100011033 under projects PID2023-151307NB-I00, PIE 20215AT016, and CEX2020-001058-M.
MG acknowledges support from an STFC PhD studentship and from the Faculty of Science and Technology at Lancaster University.
CPG acknowledges financial support from the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 Research and Innovation Programme of the European Union under the Marie Skłodowska-Curie and the Beatriu de Pinós 2021 BP 00168 programme, from the Spanish Ministerio de Ciencia e Innovación (MCIN) and the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the PID2023-151307NB-I00 SNNEXT project, from Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016 and the program Unidad de Excelencia María de Maeztu CEX2020-001058-M, and from the Departament de Recerca i Universitats de la Generalitat de Catalunya through the 2021-SGR-01270 grant.
CL is supported by DoE award no. DE-SC0025599.
Zwicky Transient Facility, W. M. Keck Observatory, and MMT Observatory access was supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).
AM gratefully acknowledges support from an STFC PhD studentship and the Faculty of Science and Technology at Lancaster University.
TEMB is funded by Horizon Europe ERC grant no. 101125877.
MN is supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 948381).
NR is supported by a Northwestern University Presidential Fellowship Award. We gratefully acknowledge the support of the NSF-Simons AI-Institute for the Sky (SkAI) via grants NSF AST-2421845 and Simons Foundation MPS-AI-00010513.
AS acknowledges the Warwick Astrophysics PhD prize scholarship made possible thanks to a generous philanthropic donation.
SJS acknowledges funding from STFC grant ST/Y001605/1, a Royal Society Research Professorship and the Hintze Family Charitable Foundation.
Volume
549
Issue
1
Article Number
stag678
ISSN
eISSN
IST-REx-ID
Cite this
Perley DA, Ho AYQ, McGrath Z, et al. AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole. Monthly Notices of the Royal Astronomical Society. 2026;549(1). doi:10.1093/mnras/stag678
Perley, D. A., Ho, A. Y. Q., McGrath, Z., Camilo, M., Sevilla, C., Chen, P., … Young, D. R. (2026). AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole. Monthly Notices of the Royal Astronomical Society. Oxford University Press. https://doi.org/10.1093/mnras/stag678
Perley, Daniel A, Anna Y Q Ho, Zoë McGrath, Michael Camilo, Cassie Sevilla, Ping Chen, Genevieve Schroeder, et al. “AT 2024wpp: An Extremely Luminous Fast Ultraviolet Transient Powered by Accretion onto a Black Hole.” Monthly Notices of the Royal Astronomical Society. Oxford University Press, 2026. https://doi.org/10.1093/mnras/stag678.
D. A. Perley et al., “AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole,” Monthly Notices of the Royal Astronomical Society, vol. 549, no. 1. Oxford University Press, 2026.
Perley DA, Ho AYQ, McGrath Z, Camilo M, Sevilla C, Chen P, Schroeder G, Govreen-Segal T, Bochenek A, Qin Y-J, Gillanders JH, Amend B, Anderson JP, Andreoni I, Aryan A, Bellm EC, Bloom JS, de Boer T, Carney J, Caiazzo I, Chambers KC, Charalampopoulos P, Chen T-W, Chen TX, Coughlin ER, Coughlin M, Dennefeld M, Dimitriadis G, Fremling C, Frostig D, Gal-Yam A, Galbany L, Gangopadhyay A, Ghendrih M, Graham MJ, Gromadzki M, Groom SL, Gutiérrez CP, Hinds K-R, Huber ME, Inserra C, Kaiser BC, Kasliwal MM, Koivisto NE, Lin C-C, Liu C, Lowe TB, Magnier E, Mahabal AA, Milligan A, Minguez P, Mo G, Müller-Bravo TE, Nicholl M, Pessi PJ, Pignata G, Purdum J, Rehemtulla N, Rich RM, Sahu A, Singh A, Smartt SJ, Smith IA, Sollerman J, Srinivasaragavan G, Srivastav S, Stein RD, Schulze S, Tweddle JW, Wainscoat R, Wise JL, Yan L, Young DR. 2026. AT 2024wpp: An extremely luminous fast ultraviolet transient powered by accretion onto a black hole. Monthly Notices of the Royal Astronomical Society. 549(1), stag678.
Perley, Daniel A., et al. “AT 2024wpp: An Extremely Luminous Fast Ultraviolet Transient Powered by Accretion onto a Black Hole.” Monthly Notices of the Royal Astronomical Society, vol. 549, no. 1, stag678, Oxford University Press, 2026, doi:10.1093/mnras/stag678.
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