AT2019cmw: a highly luminous, cooling featureless TDE candidate from the disruption of a high mass star in an early-type galaxy

Wise, JL ORCID: 0000-0003-0733-2916, Perley, DA ORCID: 0000-0001-8472-1996, Sarin, N, Matsumoto, T, Hinds, KR, Yao, Y, Sollerman, J, Schulze, S, Bochenek, A ORCID: 0009-0008-2714-2507, Coughlin, MW, De, K, Dekany, R, Frederick, S, Fremling, C, Gezari, S, Graham, MJ, Ho, AYQ, Kulkarni, S, Laher, RR, Omand, C ORCID: 0000-0002-9646-8710 et al (2026) AT2019cmw: a highly luminous, cooling featureless TDE candidate from the disruption of a high mass star in an early-type galaxy. Monthly Notices of the Royal Astronomical Society, 546 (3). pp. 1-28. ISSN 0035-8711

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Abstract

We present optical/UV photometric and spectroscopic observations, as well as X-ray and radio follow-up, of the extraordinary event AT2019cmw. With a peak bolometric luminosity of ∼ 1045.6 erg s−1, it is one of the most luminous thermal transients ever discovered. Extensive spectroscopic follow-up post-peak showed only a featureless continuum throughout its evolution. This, combined with its nuclear location, blue colour at peak and lack of prior evidence of an AGN in its host lead us to interpret this event as a ‘featureless’ tidal disruption event (TDE). It displays photometric evolution atypical of most TDEs, cooling from ∼ 30 to ∼ 10 kK in the first ∼ 300 d post-peak, with potential implications for future photometric selection of candidate TDEs. No X-ray or radio emission is detected, placing constraints on the presence of on-axis jetted emission or a visible inner-accretion disc. Modelling the optical light curve with existing theoretical prescriptions, we find that AT2019cmw may be the result of the disruption of a star in the tens of solar masses by a supermassive black hole (SMBH). Combined with a lack of detectable star formation in its host galaxy, it could imply the existence of a localized region of star formation around the SMBH. This could provide a new window to probe nuclear star formation and the shape of the initial mass function (IMF) in close proximity to SMBHs out to relatively high redshifts.

Item Type:	Article
Uncontrolled Keywords:	astro-ph.HE; astro-ph.HE; 5109 Space Sciences; 5101 Astronomical Sciences; 51 Physical Sciences; 5109 Space Sciences; 5101 Astronomical Sciences; 51 Physical Sciences; 0201 Astronomical and Space Sciences; 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:	Oxford University Press
Date of acceptance:	14 January 2026
Date of first compliant Open Access:	27 February 2026
Date Deposited:	27 Feb 2026 13:55
Last Modified:	27 Feb 2026 13:55
DOI or ID number:	10.1093/mnras/stag130
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28155

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