IGR J12580+0134: A Possible Repeated Partial Tidal Disruption Event Inferred from Late-Time Radio Re-brightenin

Abstract

Repeating partial tidal disruption events (pTDEs) provide a direct probe of stellar orbits and episodic mass loss around supermassive black holes, but robust identification requires multi-band and multi-epoch evidence. %consistent with a single physical origin. We investigate whether the late-time radio rebrightening of the nuclear transient IGR~J12580+0134 in NGC~4845 can be explained as a repeating pTDE, using multi-epoch Karl G.\ Jansky VLA observations together with X-ray constraints from \textit{Swift}/XRT and \textit{NICER}. Through a systematic analysis of the radio data, we identify two well-defined radio flares and a possible third late-time rebrightening flare. Modeling the second flare with a synchrotron afterglow framework using Markov Chain Monte Carlo fitting is consistent with a sub-relativistic outflow with a characteristic velocity of order $v\simeq 0.3c$, an isotropic-equivalent kinetic energy of order $10^{50}$ erg, and an approximately constant-density circumnuclear medium. No significant contemporaneous brightening is detected by \textit{Swift}/XRT during the 2016 radio flare, while faint \textit{NICER} flares in 2023 suggest intermittent low-level accretion. We also considered several possible interpretations for the late-time radio rebrightening, and found that the repeated pTDE scenario provides a more natural overall explanation for the observed phenomenology. Given the currently sparse data coverage, continued sensitive radio and X-ray monitoring will be essential to test this interpretation and to search for future reactivations.

17 pages, 6 figures, 2 tables, submitted to ApJ