http://arxiv.org/abs/2301.00576
One of the most fundamental and yet open issues in gamma-ray burst (GRB) physics, is the comprehension of the nature of their jet composition. The investigation of joint polarimetric and spectral properties is essential to probe the jet composition and radiation mechanism of GRBs. Several distinct categories of jet properties — the
Kinetic-energy-dominated" (KED),Poynting-flux-dominated” (PFD), and Hybrid-dominated" (HD) jets -- have been observed in the observed GRB spectra, and the emission dominated by different jet properties is expected to have a different level of polarization ($\pi_{\rm KED}\lesssim\pi_{\rm HD}\lesssim\pi_{\rm PED}$). In the present paper, we collected a GRB sample in which all the bursts detected by the Gamma-ray Burst Monitor (GBM) on board the NASA {\it Fermi} Gamma-ray Space Telescope whose polarization measurements are also reported in the literature and the epochs of prompt emission are heavily overlapped with their polarization observations, aiming to establish a connection between the polarization and jet properties of GRBs, and to confirm the validity of this correlation ($\pi_{\rm KED}\lesssim\pi_{\rm HD}\lesssim\pi_{\rm PED}$) from observations. With a detailed spectral analysis, we found that all the bursts are classified as theHybrid” jet type, implying that one cannot rule out that the photosphere emission may also be the possible mechanism powering the high levels of polarization. Finally, we present different polarization models in the presence of ordered and random magnetic field configurations with the properties of corresponding hybrid jets in order to interpret polarization measurements of the prompt emission in our sample.
L. Li and S. Shakeri
Tue, 3 Jan 23
33/49
Comments: 25 pages, 9 figures (including 23 panels), 5 tables, submitted