Lunch talk on Apr. 27, 2026

Testing Reverse-Shock Dominated Internal Shock Model Through Fitting GRB Prompt Pulses

Speaker: Kamil F. Nadaf (NJU)

Venue: SWIFAR Building 2111

Time: 12:45 PM, Monday, Apr. 27, 2026

Abstract: 

Gamma-ray bursts (GRBs) are the most energetic transients in the universe, yet the physical mechanism powering their prompt gamma-ray emission remains debated. In this talk, I will present my work on fitting individual GRB prompt pulses using the reverse-shock dominated internal shock model. In this framework, a compact central engine ejects ultra-relativistic shells of varying speeds; when a faster trailing shell collides with a slower leading shell, a pair of shocks forms—a weaker forward shock and a dominant reverse shock—whose synchrotron emission naturally reproduces the observed pulse morphology and characteristic hard-to-soft spectral evolution. I will focus on the observed $\nu_{\mathrm{peak}}$–$F_{\mathrm{peak}}$ correlation across individual pulses, which this model parameterizes with just two physical quantities: the proper velocity contrast between colliding shells and the fractional distance crossed by the shock front. I will present a preliminary analysis of a sample of single-pulse GRBs, finding consistency between the model predictions and observed pulse properties. Looking ahead, I will also outline my broader PhD research objectives, including using multi-band follow-up with MEPHISTO at Lijiang Observatory to probe the prompt-to-afterglow transition and search for short-lived optical flashes predicted by the reverse shock model.