What Sets the Line Profiles in Tidal Disruption Events?

Understand

We investigate line formation in gas that is outflowing and optically thick to electron scattering, as may be expected following the tidal disruption of a star by a super-massive black hole.

• Using radiative transfer calculations, we show that the optical line profiles produced by expanding TDE outflows are most likely primarily emission features, rather than the P-Cygni profiles seen in most supernova spectra.
• This is a result of the high line excitation temperatures in the highly irradiated TDE gas.
• The outflow kinematics cause the emission peak to be blueshifted and to have an asymmetric red wing.