Evidence of X-ray plateaus driven by the magnetar spindown winds in gamma-ray burst afterglows

TL;DR

This paper presents evidence that X-ray plateaus in some gamma-ray burst afterglows are caused by magnetar spindown winds, supporting the magnetar central engine model through analysis of Swift data.

Contribution

The study identifies three GRBs with specific X-ray features consistent with magnetar spindown, providing observational support for the magnetar central engine hypothesis.

Findings

Three GRBs show X-ray plateaus with t^{-2} decay superimposed on normal afterglow.

Magnetars are likely the central engines for these GRBs based on lightcurve features.

Future multimessenger observations can further test the magnetar model.

Abstract

The central engine of gamma-ray bursts (GRBs) remains an open and forefront topic in the era of multimessenger astrophysics. The X-ray plateaus appear in some GRB afterglows, which are widely considered to originate from the spindown of magnetars. According to the stable magnetar scenario of GRBs, an X-ray plateau and a decay phase as $\sim t^{-2}$ should appear in X-ray afterglows. Meanwhile, the ``normal'' X-ray afterglow is produced by the external shock from GRB fireball. We analyze the Neil Gehrels \emph{Swift} GRB data, then find three gold samples, which have an X-ray plateau and a decay phase as $\sim t^{-2}$ superimposed on the jet-driven normal component. Based on these features of the lightcurves, we argue that the magnetars should be the central engines of these three GRBs. Future joint multimessenger observations might further test this possibility, then which can be beneficial to constrain GRB physics.