Consequences of Strong Compression in Tidal Disruption Events

TL;DR

This paper presents a new analytic model for tidal disruption events, revealing that debris energy spread remains largely constant across different encounter depths, with implications for observations and gravitational wave detection.

Contribution

Introduces a novel analytic model for TDEs showing constant debris energy spread across beta values and assesses relativistic, stellar spin, and gravitational wave effects.

Findings

Debris energy spread is largely independent of beta.

Relativistic corrections to energy spread are minimal.

Gravitational waves from white dwarf disruptions could be detectable.

Abstract

The tidal disruption of a star by a supermassive black hole (SMBH) is a highly energetic event with consequences dependent on the degree to which the star plunges inside the SMBH's tidal sphere. We introduce a new analytic model for tidal disruption events (TDEs) to analyze the dependence of these events on beta, the ratio of the tidal radius to the orbital pericenter. We find, contrary to most previous work, that the spread in debris energy for a TDE is largely constant for all beta. This result has important consequences for optical transient searches targeting TDEs, which we discuss. We quantify leading-order general relativistic corrections to this spread in energy and find that they are small. We also examine the role of stellar spin, and find that a combination of spin-orbit misalignment, rapid rotation, and high beta may increase the spread in debris energy. Finally, we quantify for the first time the gravitational wave emission due to the strong compression of a star in a high-beta TDE. Although this signal is unlikely to be detectable for disruptions of main sequence stars, the tidal disruption of a white dwarf by an intermediate mass black hole can produce a strong signal visible to Advanced LIGO at tens of megaparsecs.