GRB 110328A/Swift J164449.3+573451: The Tidal Obliteration of a Deeply Plunging Star?

TL;DR

This paper proposes that the powerful X-ray source Sw 1644+57 results from a deeply plunging tidal obliteration event, challenging traditional tidal disruption models by suggesting an extreme orbit causes the observed phenomena.

Contribution

The study introduces the concept of a tidal obliteration event (TOE) as an alternative to traditional tidal disruption events, emphasizing a deeply plunging star orbit as the cause.

Findings

Deeply plunging orbit is necessary to explain the observed jet power.

Traditional TDE models cannot account for the early X-ray light curve.

The event rate supports a deeply plunging orbit scenario.

Abstract

We examine the tidal disruption event scenario to explain Sw 1644+57, a powerful and persistent X-ray source which suddenly became active as GRB 110328A. The precise localization at the center of a z=0.35 galaxy argues for activity of the central engine as the underlying cause. We look at the suggestion by Bloom et al of the possibility of a tidal disruption event (TDE). We argue that Sw 1644+57 cannot be explained by the traditional TDE model in which the periastron distance is close to the tidal disruption radius - three independent lines of argument indicate the orbit must be deeply plunging or else the powerful jet we are observing could not be produced. These arguments stem from (i) comparing the early X-ray light curve to the expected theoretical fallback rate, (ii) looking at the time of transition to disk-dominated decay, and (iii) considering the TDE rate. Due to the extreme excess in the tidal force above that which would be required minimally to disrupt the star in a deeply plunging orbit at periastron, we suggest this scenario might be referred to more descriptively as a TOE (tidal obliteration event) rather than a TDE.