Title:
Accretion Disk Winds in Tidal Disruption Events: 
Ultraviolet Spectral Lines as Orientation Indicators

Abstract:
Several tidal disruption events (TDEs) exhibit blueshifted, 
broad absorption lines (BALs) in their rest-frame ultraviolet (UV) spectra, 
while other TDEs display only broad emission lines (BELs). 
The same phenomenology is also observed in quasars and accreting white dwarfs, 
where it is interpreted as an orientation effect associated with line formation 
in an accretion disk wind.

In this talk, we explore a similar unification scheme for TDEs. 
Specifically, we present synthetic UV spectra for disk- and wind-hosting TDEs, 
as produced by our state-of-the-art Monte Carlo ionization and radiative transfer code. 
Our models cover a wide range of disk wind geometries and kinematics, 
and we also study the effect of wind clumping on the observed spectra. 
As some TDEs may involve the disruption of evolved, intermediate mass stars, 
we additionally consider both solar and CNO-processed abundance profiles for 
the ejected material.

Our main result is that the observed diversity of UV line profile shapes (BALs vs BELs) 
can indeed be explained by disk wind models. In general, sight lines looking into 
the wind cone preferentially produce BALs, while other orientations - 
and especially highly edge-on viewing angles - preferentially produce BELs. 
In such a disk wind scenario, the relative number of BAL and BEL TDEs can 
therefore be used to estimate the covering factor of the outflow. 
Clumping and abundance variations do not change this basic picture, 
but can nevertheless significantly alter the observed UV spectrum.