Fermi Gamma-ray Space Telescope

Observed Spectral Correlations in Fermi/GBM GRB Single Pulses using Bayesian Statistics

Hoi Fung David Yu
(Hüsne Dereli-Bégué, Felix Ryde)


We performed Bayesian time-resolved spectroscopy on a sample of gamma-ray burst pulses from 40 bursts observed by the Fermi/Gamma-ray Burst Monitor during its first 9 years of mission. We study their spectral evolution properties and the overall spectral parameter distributions. We discuss and compare the Bayesian spectral fit results using two most frequently used empirical photon models: the cutoff power law and Band function. Two apparent correlations in the spectral parameters are observed: low-energy power-law index versus flux, and spectral peak energy versus low-energy power-law index, and we discuss their possible origins.