X-ray plateaus followed by sharp drops in GRBs 060413, 060522, 060607A and 080330: Further evidences for central engine afterglow from Gamma-ray Bursts

TL;DR

This paper studies peculiar X-ray afterglows in certain GRBs, proposing they are powered by magnetar central engines, with sharp drops indicating magnetar collapse, and predicts high polarization in plateau photons.

Contribution

It introduces a magnetar-based model for X-ray afterglows with sharp drops, linking them to internal magnetic energy dissipation and magnetar collapse.

Findings

X-ray plateaus are consistent with external forward shock models.

Sharp drops suggest magnetar collapse as the cause.

High polarization of plateau photons is predicted.

Abstract

The X-ray afterglows of GRBs 060413, 060522, 060607A and 080330 are characterized by plateaus that are followed by very sharp drops. An X-ray plateau is interpretable within the framework of the external forward shock model but the sharp drop is not. In this work we interpret these peculiar X-ray afterglow data as the central engine afterglows from some magnetized central engines, plausibly magnetars. In this model, the X-ray afterglows are powered by the internal magnetic energy dissipation and the sudden drop is caused by the collapse of the magnetar. Accordingly, the X-ray plateau photons should have a high linear polarization, which can be tested by the future X-ray polarimetry.