The Wandering Supermassive Black Hole Powering the Off-nuclear Tidal Disruption Event AT2024tvd

Abstract We present an analysis of the spectral energy distribution (SED) of the off-nuclear tidal disruption event (TDE) AT2024tvd during its late-time plateau phase, combining X-ray spectra and UV/optical photometry. Using a fully relativistic, compact accretion disk model with self-consistent inner-disk Comptonization, we reproduce the observed SED without significant residuals. The inferred black hole mass log 10 ( M • / M ⊙ ) ≈ 6.0 ± 0.2 , and the inferred disk parameters place AT2024tvd within known TDE-disk scaling relations ( L bol disk / L Edd ∝ T p 4 ∝ M • − 1 , L plat ∝ M • 2 / 3 , R out / r g ∝ M • − 2 / 3 ). Our results show that: (i) there is no currently detected star cluster or dwarf galaxy associated with the source, down to a mass limit of log 10 ( M gal / M ⊙ ) ≤ 7.6 ; (ii) the black hole is a wandering supermassive, rather than intermediate-mass, black hole; and (iii) the source represents an extreme case of black hole-to-host mass ratio, with M • / M gal > 3%, consistent with a heavily tidally stripped nucleus. The latter aligns with cosmological simulations predicting that surviving host remnants of most wandering black holes should not retain a detectable stellar overdensity when located at small halo-centric distances. We discuss differences with previous analyses of this source and highlight why our modeling approach provides a more physic