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

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 $B_{\mathrm{p}}=13.24_{-5.84}^{+1.73}\times 10^{15}\mathrm{G}$ and an initial spin period $P_0=14.31_{-3.16}^{+0.93}\mathrm{ms}$ 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 $\epsilon -$distribution of GBR 250114A with those of other high-$z$ sample-GRBs, and find no significant statistical differences between them.

16 pages, 7 figures, and 3 tables. Accepted for publication in ApJ