2025/08/05 by Itai Sfaradi, Raffaella Margutti, Sfaradi, Itai +71 · 2 voices · 1 citation
Physics and Astronomy · #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #astro-ph.HE
paper · pdf · doi:10.48550/arxiv.2508.03807
We present the first multi-epoch broadband radio and millimeter monitoring of an off-nuclear TDE using the VLA, ALMA, ATA, AMI-LA, and the SMA. The off-nuclear TDE 2024tvd exhibits double-peaked radio light curves and the fastest evolving radio emission observed from a TDE to date. With respect to the optical discovery date, the first radio flare rises faster than F\rm ν ∼ t9 at Δt = 88-131 days, and then decays as fast as F\rm ν ∼ t-6. The emergence of a second radio flare is observed at Δt ≈ 194 days with an initial fast rise of F\rm ν ∼ t18, and an optically thin decline of F\rm ν ∼ t -12. We interpret these observations in the context of a self-absorbed and free-free absorbed synchrotron spectrum, while accounting for both synchrotron and external inverse-Compton cooling. We find that a single prompt outflow cannot easily explain these observations and it is likely that either there is only one outflow that was launched at Δt ∼ 80 days, or two distinct outflows, with the second launched at Δt ∼ 170-190 days. The nature of these outflows, whether sub-, mildly-, or ultra-relativistic, is still unclear, and we explore these different scenarios. Finally, we find a temporal coincidence between the launch time of the first radio-emitting outflow and the onset of a power-law component in the X-ray spectrum, attributed to inverse-Compton scattering of thermal photons.