A Luminous Red Optical Flare and Hard X-Ray Emission in the Tidal Disruption Event AT 2024kmq

Ho, AYQ ORCID: 0000-0002-9017-3567, Yao, Y ORCID: 0000-0001-6747-8509, Matsumoto, T ORCID: 0000-0002-3809-0000, Schroeder, G ORCID: 0000-0001-9915-8147, Coughlin, ER ORCID: 0000-0003-3765-6401, Perley, DA ORCID: 0000-0001-8472-1996, Andreoni, I ORCID: 0000-0002-8977-1498, Bellm, EC ORCID: 0000-0001-8018-5348, Chen, TX ORCID: 0000-0001-9152-6224, Chornock, R ORCID: 0000-0002-7706-5668, Covarrubias, S ORCID: 0000-0003-1858-561X, Das, K ORCID: 0000-0001-8372-997X, Fremling, C ORCID: 0000-0002-4223-103X, Gilfanov, M, Hinds, KR ORCID: 0000-0002-0129-806X, Jarvis, D ORCID: 0009-0004-3067-2227, Kasliwal, MM ORCID: 0000-0002-5619-4938, Liu, C ORCID: 0000-0002-7866-4531, Lyman, JD ORCID: 0000-0002-3464-0642, Masci, FJ ORCID: 0000-0002-8532-9395 et al (2025) A Luminous Red Optical Flare and Hard X-Ray Emission in the Tidal Disruption Event AT 2024kmq. The Astrophysical Journal, 989 (1). ISSN 0004-637X

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Abstract

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.

Item Type:	Article
Uncontrolled Keywords:	0201 Astronomical and Space Sciences; 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics; 0306 Physical Chemistry (incl. Structural); Astronomy & Astrophysics; 5101 Astronomical sciences; 5107 Particle and high energy physics; 5109 Space sciences
Subjects:	Q Science > QB Astronomy Q Science > QC Physics
Divisions:	Astrophysics Research Institute
Publisher:	American Astronomical Society
Date of acceptance:	29 May 2025
Date of first compliant Open Access:	13 August 2025
Date Deposited:	13 Aug 2025 10:09
Last Modified:	13 Aug 2025 10:15
DOI or ID number:	10.3847/1538-4357/ade8f2
URI:	https://researchonline.ljmu.ac.uk/id/eprint/26929

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