Tidal disruption of stellar binaries as a pathway to exotic transients

Abstract: Tidal disruption event (TDE) progenitors are commonly modelled as single stars on parabolic orbits around a supermassive black hole (SMBH), yet observations point to a richer diversity of dynamical pathways. We show that the tidal separation of stellar binaries by a $10<sup>6\,M_\odot$ SMBH provides a natural mechanism for producing eccentric TDEs. Using restricted three-body dynamics and smoothed particle hydrodynamics (SPH) simulations, we model a binary composed of a solar-like star (SLS) and a white dwarf (WD) on a parabolic orbit. The binary orbital phase governs the outcome: one component is captured onto a tightly bound orbit while the other is ejected as a hypervelocity object, naturally producing TDEs with eccentricities $e \neq 1$. We classify the resulting events into Elliptical TDEs (eTDEs) and Hyperbolic TDEs (hTDEs), which occur with equal probability. For $\sim 88\%$ of binary orientations the disruption is clean, with no mass accreted by the WD. The remaining $\sim 12\%$ lies in two narrow windows of binary phase in which the WD captures material and becomes a WD with debris envelope (WDDE). About a third of that range, $\sim 4\%$ of all orientations, involves a direct WD--SLS collision near pericenter, giving fallback that peaks up to five times earlier and twenty times higher than in the single-star case; for the innermost $\sim 1.5\%$ the total WDDE mass exceeds $1.4\,M_\odot$, although the degenerate core itself does not, since the captured material forms a non-degenerate envelope. This suggests outcomes ranging from nova-like events to peculiar red giant-like objects. Depending on the binary phase, the mechanism may also produce repeating partial TDEs (rTDEs) and quasi-periodic eruptions (QPEs). Binary--SMBH encounters thus provide a robust channel for generating diverse TDEs with distinct observational signatures.