AT2024wpp: An Extremely Luminous Fast Ultraviolet Transient Powered by Accretion onto a Black Hole
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 (2x10^45 erg/s), maximum photospheric radius (10^15 cm), and total radiated energy (10^51 erg) of an 18cow-like object. We present results from a comprehensive multiwavelength observing campaign, including a far-UV spectrum from the Cosmic Origins Spectrograph on the Hubble Space Telescope and deep imaging extending >100 days 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 (~0.2c) 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 days in the form of double-peaked narrow lines. Each peak is individually narrow (full width ~3000 km/s) but the two components are separated by ~6600 km/s, indicating stable structures of denser material, possibly representing streams of tidal ejecta or an ablated companion star.
Keywords
Cite
@article{arxiv.2601.03337,
title = {AT2024wpp: An Extremely Luminous Fast Ultraviolet Transient Powered by Accretion onto a Black Hole},
author = {Daniel A. Perley and Anna Y. Q. Ho and Zoë McGrath and Michael Camilo and Cassie Sevilla and Ping Chen and Genevieve Schroeder and Taya Govreen-Segal and Aleksandra Bochenek and Yu-Jing Qin and James H. Gillanders and Benjamin Amend and Joseph P. Anderson and Igor Andreoni and Amar Aryan and Eric C. Bellm and Joshua S. Bloom and Thomas de Boer and Jonathan Carney and Ilaria Caiazzo and Ken C. Chambers and Panos Charalampopoulos and Ting-Wan Chen and Tracy X. Chen and Eric R. Coughlin and Michael Coughlin and Michel Dennefeld and Georgios Dimitriadis and Christoffer Fremling and Danielle Frostig and Avishay Gal-Yam and Lluís Galbany and Anjashay Gangopadhyay and Melzie Ghendrih and Matthew J. Graham and Mariusz Gromadzki and Steven L. Groom and Claudia P. Gutiérrez and K. -Ryan Hinds and Mark E. Huber and Cosimo Inserra and Benjamin C. Kaiser and Mansi M. Kasliwal and Niilo E. Koivisto and Chien-Cheng Lin and Chang Liu and Thomas B. Lowe and Eugene Magnier and Ashish A. Mahabal and Andrew Milligan and Paloma Minguez and Geoffrey Mo and Tomás E. Müller-Bravo and Matt Nicholl and Priscila J. Pessi and Giuliano Pignata and Josiah Purdum and Nabeel Rehemtulla and R. Michael Rich and Anwesha Sahu and Avinash Singh and Stephen J. Smartt and Jesper Sollerman and Gokul Srinivasaragavan and Shubham Srivastav and Robert D. Stein and Steve Schulze and Jack W. Tweddle and Richard Wainscoat and Jacob L. Wise and Lin Yan and David R. Young},
journal= {arXiv preprint arXiv:2601.03337},
year = {2026}
}
Comments
Accepted to MNRAS. Machine-readable radio and optical photometry tables included as ancillary files