X-Ray afterglow of SWIFT J1644+57: a Compton echo?

TL;DR

This paper proposes that the long-lasting X-ray afterglow of Swift J1644+57 is due to a Compton echo effect caused by Thomson scattering, marking the first such observation at cosmological distances.

Contribution

It introduces the idea that the X-ray afterglow results from a Compton echo, a novel interpretation for this astrophysical phenomenon at cosmological scales.

Findings

X-ray afterglow appears at ~500 days and persists until ~1400 days.

The afterglow is explained by Thomson scattering, not standard tidal disruption.

First potential observation of a Compton echo at cosmological distances.

Abstract

Swift, Chandra and XMM have found a weak but nearly constant X-ray component from Swift J1644+57 that appeared at ~500 days and was visible at least until ~ 1400 days after the stellar capture, which cannot be explained by standard tidal disruption theories. We suggest that this X-ray afterglow component may result from Thomson scattering between the primary X-rays and its surrounding plasma, i.e. the Compton echo effect. Similar phenomena has also been observed from molecular clouds in our Galactic Center, which were caused by the past activity of Srg A*. If this interpretation of Swift J1644+57 afterglow is correct, this is the first Compton Echo effect observed in the cosmological distances.