AT2019aalc: An obscured tidal disruption event candidate in an active galactic nucleus revealed by its first flare?
Year: 2026
Type: article
Abstract: AT2019aalc is considered a repeating tidal disruption event (TDE) candidate occurring in an active galactic nucleus (AGN). In this paper, we highlight previously unnoticed but intriguing features that include a brief optical dimming prior to the rise of the main flare and a significantly lower post-flare luminosity compared to the pre-flare level. By applying a time-dependent obscured TDE model to AT2019aalc, we successfully reproduce its light curves with the tidal disruption of a 1.122 −0.176 +0.246 main-sequence star by a 1.862 −0.259 +0.255 × 107 M ⊙ supermassive black hole (SMBH). Both the pre-flare dimming and the reduced post-flare luminosity are attributed to obscuration of the intrinsic AGN emission. The total energy of the event derived from our fit is 1.24 × 10 51 erg and about 0.2 M ⊙ of debris mass is accreted by the SMBH. In addition, the g − r color of the net flare in AT2019aalc exhibits a continuous reddening trend during the first flare, consistent with a gradual increase in E ( B − V ) predicted by the obscured TDE model. These results suggest that AT2019aalc can be considered a second member of the recently proposed class of obscured TDE candidates hosted in AGNs.
Source: Astronomy and Astrophysics
Authors: Ying Gu, Xiao Li, Xue-Guang Zhang, En-Wei Liang
Institutions: Guangxi University, Northwest Normal University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Awards: G4330545635, G5869244447, G9094182
OpenAlex ID: W7213929576