Probing the Nature of High-Redshift Long GRB 250114A and Its Magnetar Central Engine

TL;DR

This paper investigates the high-redshift long GRB 250114A, proposing a magnetar central engine based on X-ray light curve fitting, and compares its properties with other high-redshift GRBs, finding no significant differences.

Contribution

It introduces a magnetar model for GRB 250114A's central engine and provides detailed estimates of its magnetic field and spin period, expanding understanding of high-redshift GRB engines.

Findings

Magnetar with Bp ≈ 13.24×10^{15} G and P0 ≈ 14.31 ms fits the X-ray light curve.

No significant statistical differences between high-z GRB 250114A and other high-redshift GRBs.

Continuous central engine activity suggested by X-ray emission during quiescent intervals.

Abstract

GRB 250114A is a long-duration gamma-ray burst (GRB) which triggered the Swift/BAT with a spectroscopic high-redshift at $z = 4.732$. The light curve of the prompt emission is composed of three distinct emission episodes, which are separated by quiescent gaps ranging from tens to hundreds of seconds. While the X-ray light curve exhibits the canonical X-ray emission which is composed of several power-law segments superposition of a giant X-ray flare. More interestingly, there is still significant X-ray emission during the quiescent time in the prompt emission, suggesting a continuously active central engine whose power fluctuates across the $\gamma$-ray detectability threshold. In this paper, we propose a magnetar as the central engine of GRB 250114A by fitting the X-ray light curve, and infer a magnetic field strength $B_{\rm p}=13.24^{+1.73}_{-5.84} \, \times10^{15}\ \mathrm{G}$ and an initial spin period $P_{0}=14.31^{+0.93}_{-3.16} \, \mathrm{ms}$ of magnetar, with a jet correction, fall within a reasonable range. Furthermore, we also compare the prompt emission, X-ray afterglow, $E_{\mathrm p}$-$E_{\gamma,\mathrm{iso}}$, and $\varepsilon-$distribution of GBR 250114A with those of other high-$z$ sample-GRBs, and find no significant statistical differences between them.