Extreme Nuclear Transients Resulting from the Tidal Disruption of Intermediate Mass Stars

Modern transient surveys now routinely discover flares resulting from tidal disruption events (TDEs) which occur when stars, typically ∼0.5-2 M_⊙, are ripped apart after passing too close to a supermassive black hole. We present three examples of a new class of extreme nuclear transients (ENTs) that we interpret as the tidal disruption of intermediate mass (∼3-10 M_⊙) stars. Each is coincident with their host-galaxy nucleus and exhibits a smooth (<10 (2-7×10^45 erg s^-1), and long-lived (>150 days) flare. ENTs are extremely rare (≥1×10^-3 Gpc^-1 yr^-1) compared to any other known class of transients. They are at least twice as energetic (0.5-2.5× 10^53 erg) as any other known transient and these extreme energetics rule out stellar origins.