Disk Winds as an Explanation for Slowly Evolving Temperatures in Tidal Disruption Events

TL;DR

This paper proposes that strong disk winds, driven by high accretion rates, can explain the observed low and slowly evolving temperatures in tidal disruption events, challenging standard disk models.

Contribution

It introduces a wind-based model for TDE temperature evolution and links it to the debris circularization radius, providing a new perspective on TDE dynamics.

Findings

Wind strength correlates with accretion rate, affecting temperature evolution.

Quantitative agreement with TDE data supports the wind-driven model.

Circularization radius near the most bound orbit explains temperature behavior.

Abstract

Among the many intriguing aspects of optically discovered tidal disruption events (TDEs) is that their temperatures are lower than expected and that the temperature does not evolve as rapidly with decreasing fallback rate as would be expected in standard disk theory. We show that this can be explained qualitatively using an idea proposed by Laor & Davis in the context of normal active galactic nuclei: that larger accretion rates imply stronger winds and thus that the accretion rate through the inner disk only depends weakly on the inflow rate at the outer edge of the disk. We also show that reasonable quantitative agreement with data requires that, as has been suggested in recent papers, the circularization radius of the tidal stream is approximately equal to the semimajor axis of the most bound orbit of the debris rather than twice the pericenter distance as would be expected without rapid angular momentum redistribution. If this explanation is correct, it suggests that the evolution of TDEs may test both non-standard disk theory and the details of the interactions of the tidal stream.