Magnetar central engine powering the energetic GRB 210610B ?

TL;DR

This study analyzes the prompt emission and afterglow of GRB 210610B, suggesting a magnetar as the central engine due to spectral features and energy considerations, with evidence of hybrid jet composition and complex afterglow behavior.

Contribution

It provides detailed spectral analysis indicating a hybrid jet and supports the magnetar central engine hypothesis for GRB 210610B.

Findings

CPL + BB model fits the data better, indicating hybrid jet composition.

Beaming-corrected energy is less than the magnetar's total energy.

X-ray afterglow exhibits achromatic plateaus with energy release below magnetar energy budget.

Abstract

The bright GRB 210610B was discovered simultaneously by Fermi and Swift missions at redshift 1.13. We utilized broadband Fermi-GBM observations to perform a detailed prompt emission spectral analysis and to understand the radiation physics of the burst. Our analysis displayed that the low energy spectral index ($\alpha_{\rm pt}$) exceeds boundaries expected from the typical synchrotron emission spectrum (-1.5,-0.67), suggesting additional emission signature. We added an additional thermal model with the typical Band or CPL function and found that CPL + BB function is better fitting to the data, suggesting a hybrid jet composition for the burst. Further, we found that the beaming corrected energy (E$_{\rm \gamma, \theta_{j}}$ = 1.06 $\times$ 10$^{51}$ erg) of the burst is less than the total energy budget of the magnetar. Additionally, the X-ray afterglow light curve of this burst exhibits achromatic plateaus, adding another layer of complexity to the explosion's behavior. Interestingly, we noted that the X-ray energy release during the plateau phase (E$_{\rm X,iso}$ = 1.94 $\times$ 10$^{51}$ erg) is also less than the total energy budget of the magnetar. Our results indicate the possibility that a magnetar could be the central engine for this burst.