Unveiling the Multifaceted GRB 200613A: Prompt Emission Dynamics, Afterglow Evolution, and the Host Galaxy's Properties

We present our optical observations and multiwavelength analysis of the GRB 200613A detected by the Fermi satellite. Time-resolved spectral analysis of the prompt gamma-ray emission was conducted utilizing the Bayesian block method to determine statistically optimal time bins. Based on the Bayesian Information Criterion, the data generally favor the Band+blackbody (BB) model. We speculate that the main Band component comes from the Blandford-Znajek mechanism, while the additional BB component comes from the neutrino annihilation process. The BB component becomes significant for a low-spin, high-accretion-rate black hole central engine, as evidenced by our model comparison with the data. The afterglow light curve exhibits typical power-law decay, and its behavior can be explained by the collision between the ejecta and the constant interstellar medium. Model fitting yields the following parameters: EK,iso=(2.04-1.50+11.8)x1053 erg, Gamma 0=354-217+578 , p=2.09-0.03+0.02 , n18=(2.04-1.87+9.71)x102 cm-3, theta j=24.0-5.54+6.50 degree, & varepsilon;e=1.66-1.39+4.09)x10-1 and & varepsilon;B=(7.76-5.9+48.5)x10-6 . In addition, we employed the public Python package Prospector to perform a spectral energy distribution modeling of the host galaxy. The results suggest that the host galaxy is a massive galaxy ( log(M*/M circle dot)=11.75-0.09+0.10 ) with a moderate star formation rate ( SFR=22.58-7.22+13.63M circle dot yr-1). This SFR is consistent with the SFR of similar to 34.2M circle dot yr-1 derived from the [O ii] emission line in the observed spectrum.