Testing the Gamma-Ray Burst Pulse Start Conjecture

TL;DR

This study tests whether gamma-ray burst pulses begin simultaneously across all energies, supporting the idea of a common start time, with implications for understanding energy injection and spectral evolution in GRBs.

Contribution

It provides empirical evidence supporting the Pulse Start Conjecture for Long GRBs using BATSE data, clarifying the timing and spectral evolution of GRB pulses.

Findings

Supports the Pulse Start Conjecture for Long GRBs

Uncertainty in pulse start timing is less than 0.4 seconds

Energy injection occurs at the start of each GRB pulse

Abstract

We test the hypothesis that prompt gamma-ray burst pulse emission starts simultaneously at all energies (the Pulse Start Conjecture). Our analysis, using a sample of BATSE bursts observed with four channel, 64-ms data and performed using a pulse fit model, generally supports this hypothesis for the Long GRB class, although a few discrepant pulses belong to bursts observed during times characterized by low signal-to-noise, hidden pulses, and/or significant pulse overlap. The typical uncertainty in making this statement is < 0.4 s for pulses in Long GRBs (and < 0.2 s for 40% of the pulses) and perhaps < 0.1 s for pulses in Short GRBs. When considered along with the Epk decline found in GRB pulse evolution, this result implies that energy is injected at the beginning of each and every GRB pulse, and the subsequent spectral evolution, including the pulse peak intensity, represents radiated energy losses from this initial injection.