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) that triggered the Swift/Burst Alert Telescope 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. Meanwhile, the X-ray light curve exhibits the canonical X-ray emission that 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">p</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>13.2</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>5.84</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>1.73</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>15</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="1em"/> <mml:mi mathvariant="normal">G</mml:mi> </mml:math> and an initial spin period <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>P</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>14.3</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3.16</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.93</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">ms</mml:mi> </mml:math> of magnetar, with a jet correction, fall within a reasonable range. Furthermore, we also compare the prompt emission, X-ray afterglow, E p – E γ ,iso , and ε − distribution of GBR 250114A with those of other high- z sample-GRBs and find no significant statistical differences between them.