We present the optical discovery and multiwavelength follow-up observations of AT 2024kmq, a likely tidal disruption event (TDE) associated with a supermassive (MBH ∼ 108 M⊙) black hole in a massive galaxy at z = 0.192. The optical light curve of AT 2024kmq exhibits two distinct peaks: an early fast (timescale 1 day) and luminous (M ≈ −20 mag) red peak, then a slower (timescale 1 month) blue peak with a higher optical luminosity (M ≈ −22 mag) and featureless optical spectra. The second component is similar to the spectroscopic class of “featureless TDEs” in the literature, and during this second component we detect highly variable, luminous (LX ≈ 1044 erg s−1), and hard (fν ∝ ν−1.5) X-ray emission. Luminous (1029 erg s−1 Hz−1 at 10 GHz) but unchanging radio emission likely arises from an underlying active galactic nucleus. The luminosity, timescale, and color of the early red optical peak can be explained by synchrotron emission, or alternatively by thermal emission from material at a large radius (R ≈ a few × 1015 cm). Possible physical origins for this early red component include an off-axis relativistic jet, and shocks from self-intersecting debris leading to the formation of the accretion disk. Late-time radio observations will help distinguish between the two possibilities.
A Luminous Red Optical Flare and Hard X-Ray Emission in the Tidal Disruption Event AT 2024kmq
Creators
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Ho, Anna Y. Q.1
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Yao, Yuhan2, 3
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Matsumoto, Tatsuya4
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Schroeder, Genevieve1
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Coughlin, Eric R.5
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Perley, Daniel A.6
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Andreoni, Igor7
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Bellm, Eric C.8
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Chen, Tracy X.9
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Chornock, Ryan3
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Covarrubias, Sofia10
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Das, Kaustav10
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Fremling, Christoffer10
- Gilfanov, Marat11
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Hinds, K. R.6
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Jarvis, Dan12
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Kasliwal, Mansi M.10
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Liu, Chang13
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Lyman, Joseph D.14
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Masci, Frank J.9
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Prince, Thomas A.10
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Ravi, Vikram10
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Rich, R. Michael15
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Riddle, Reed10
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Sevilla, Cassie1
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Smith, Roger10
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Sollerman, Jesper16
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Somalwar, Jean J.10
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Srinivasaragavan, Gokul P.17, 18
- Sunyaev, Rashid11
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Vail, Jada L.1
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Wise, Jacob L.6
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Yun, Sol Bin10
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1.
Cornell University
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2.
New York State Office for People With Developmental Disabilities
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3.
University of California, Berkeley
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4.
Kyoto University
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5.
Syracuse University
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6.
Liverpool John Moores University
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7.
University of North Carolina at Chapel Hill
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8.
University of Washington
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Infrared Processing and Analysis Center
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10.
California Institute of Technology
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11.
Max Planck Institute for Astrophysics
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12.
University of Sheffield
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13.
Northwestern University
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14.
University of Warwick
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University of California, Los Angeles
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Stockholm University
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University of Maryland, College Park
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18.
Goddard Space Flight Center
Abstract
Copyright and License
© 2025. The Author(s). Published by the American Astronomical Society.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
A.Y.Q.H. would like to thank Eliot Quataert, Dong Lai, and Wenbin Lu for helpful conversations regarding TDE models as well as Krista Lynne Smith for discussions about radio AGN. Eric R. Coughlin acknowledges support from NASA through the Astrophysics Theory Program, grant 80NSSC24K0897. J.D.L. acknowledges support from a UK Research and Innovation Future Leaders Fellowship (MR/T020784/1). I.A. is supported by NSF AST2407924 and NASA ADAP24-0159. C.L. is supported by DoE award #DE-SC0025599. J.S. is supported by NASA award 80NSSC24K0377.
This work was performed in part at the Aspen Center for Physics, which is supported by National Science Foundation grant PHY-2210452.
Based on observations obtained with the Samuel Oschin telescope 48 inch and the 60 inch telescope at the Palomar Observatory as part of the ZTF project. ZTF is supported by the National Science Foundation under grant No. AST-2034437 and a collaboration including Caltech, IPAC, the Oskar Klein Centre 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 ZTF forced-photometry service was funded under Heising-Simons Foundation grant No. 12540303 (PI: Graham). The Gordon and Betty Moore Foundation, through both the Data-driven Investigator Program and a dedicated grant, provided critical funding for SkyPortal.
SEDM is based on work supported by the National Science Foundation under grant No. 1106171. Data were obtained at the Lick Observatory, which is a multicampus research unit of the University of California. 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.
Based 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.
This work uses data obtained with the eROSITA telescope on board the SRG observatory. The SRG observatory was built by Roskosmos with the participation of the Deutsches Zentrum für Luft- und Raumfahrt (DLR). The SRG/eROSITA X-ray telescope was built by a consortium of German institutes led by MPE, and supported by DLR. The SRG spacecraft was designed, built, and launched and is operated by the Lavochkin Association and its subcontractors. The science data were downlinked via the Deep Space Network Antennae in Bear Lakes, Ussurijsk, and Baykonur, funded by Roskosmos. The eROSITA data used in this work were processed using the eSASS software system developed by the German eROSITA Consortium and proprietary data reduction and analysis software developed by the Russian eROSITA Consortium.
The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under a cooperative agreement by Associated Universities, Inc.
LOFAR is the Low-frequency Array designed and constructed by ASTRON. It has observing, data processing, and data storage facilities in several countries, which are owned by various parties (each with its own funding sources), and which are collectively operated by the International LOFAR Telescope (ILT) foundation under a joint scientific policy. The ILT resources have benefited from the following recent major funding sources: CNRS-INSU, Observatoire de Paris, and Université d’Orléans, France; BMBF, MIWF-NRW, and MPG, Germany; Science Foundation Ireland and Department of Business, Enterprise and Innovation (DBEI), Ireland; NWO, the Netherlands; the Science and Technology Facilities Council, UK; Ministry of Science and Higher Education, Poland; and the Istituto Nazionale di Astrofisica (INAF), Italy.
This research made use of the Dutch national e-infrastructure with support of the SURF Cooperative (e-infra 180169) and the LOFAR e-infra group. The Jülich LOFAR Long Term Archive and the German LOFAR network are both coordinated and operated by the Jülich Supercomputing Centre (JSC), and computing resources on the supercomputer JUWELS at JSC were provided by the Gauss Centre for Supercomputing e.V. (grant CHTB00) through the John von Neumann Institute for Computing.
This research made use of the University of Hertfordshire high-performance computing facility and the LOFAR-UK computing facility located at the University of Hertfordshire and supported by STFC [ST/P000096/1], and of the Italian LOFAR IT computing infrastructure supported and operated by INAF, and by the Physics Department of Turin University (under an agreement with Consorzio Interuniversitario per la Fisica Spaziale) at the C3S Supercomputing Centre, Italy.
This scientific work uses data obtained from Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory. We acknowledge the Wajarri Yamaji people as the traditional owners and native title holders of the Observatory's site. CSIRO’s ASKAP radio telescope is part of the Australia Telescope National Facility (https://ror.org/05qajvd42). Operation of ASKAP is funded by the Australian Government with support from the National Collaborative Research Infrastructure Strategy. ASKAP uses the resources of the Pawsey Supercomputing Research Centre. ASKAP, Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory, and the Pawsey Supercomputing Research Centre are initiatives of the Australian Government, with support from the Government of Western Australia and the Science and Industry Endowment Fund.
This paper includes archived data obtained through the CSIRO ASKAP Science Data Archive, CASDA (http://data.csiro.au).
Facilities
PO:1.2m - , Keck:I - KECK I Telescope, Shane - Lick Observatory's 3m Shane Telescope, Swift - Swift Gamma-Ray Burst Mission, EVLA - Expanded Very Large Array, LDT - , Liverpool:2m - Liverpool 2 meter telesope at Observatorio del Roque de los Muchachos.
Software References
CASA (J. P. McMullin et al. 2007), Astropy (Astropy Collaboration et al. 2013, 2018, 2022).
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2502.07885 (arXiv)
Funding
- National Aeronautics and Space Administration
- 80NSSC24K0897
- UK Research and Innovation
- MR/T020784/1
- National Science Foundation
- AST2407924
- National Aeronautics and Space Administration
- ADAP24-0159
- United States Department of Energy
- DE-SC0025599
- National Aeronautics and Space Administration
- 80NSSC24K0377
- National Science Foundation
- PHY-2210452
- National Science Foundation
- AST-2034437
- Heising-Simons Foundation
- 12540303
- Gordon and Betty Moore Foundation
- National Science Foundation
- 1106171
- W. M. Keck Foundation
Dates
- Accepted
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2025-05-29
- Available
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2025-08-05Published