Study the origin of GRB 231115A, short gamma-ray burst or magnetar giant flare?

Yun Wang, Yu-Jia Wei, Hao Zhou, Jia Ren, Zi-Qing Xia, Zhi-Ping Jin

Published 2023-12-05Version 1

The so called magnetars are young neutron stars with extremely high magnetic fields ($B \sim 10^{14}-10^{15}$ gauss) which usually accompanied by X-ray radiation. Soft Gamma-ray Repeating sources (SGRs), as a type of magnetar, occasionally produce giant flares (GFs) with energies ranging from 10$^{44}$ to 10$^{46}$ erg. In reality, some Gamma-Ray Bursts (e.g., GRBs 051103, 070201, 200415A) have been considered to be GFs. They have similar characteristics to short GRBs, such as spike-like light curves and hard spectra. Recently observed GRB 231115A can be categorized as one of GFs with a high probability to associated with M82. In this work, we conduct a detailed analysis of its prompt emission observed by Fermi-GBM, and compare relevant features (e.g., the $E_{\rm p,z}$--$E_{\gamma,\rm iso}$ relation) with existing observations. We find its features are almost consistent with previous GFs. We notice, however, the possibility of being a short GRB of this burst cannot be simply ruled out based on the upper limit of existing observations and the modeling of its multi-wavelength afterglow. Additionally, such events are likely to be detected by existing and future facilities, which is crucial for the physics of transient sources related to magnetars.