Correlative Characteristics of Double-Pulsed Gamma Ray Bursts

As the most energetic explosion in the universe, the gamma-ray burst (GRB) presents many unanswered questions. Comprised of photons with energies of around 100keV, the GRB is difficult to detect and can only be observed using space telescopes. In a 1990s survey with the Burst And Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory (CGRO), data on over 2700 gamma-ray bursts was collected [1]. Data was recorded on a 64 ms timescale in four separate energy channels: 25-50, 50-100, 100-300, and > 300 keV [2]. In previous work [3], two GRB classes have been recognized based on duration and spectral hardness. Other pulse properties provide important constraints on GRB physics; properties include temporal asymmetry, hard-tosoft spectral evolution, and broadening at lower energies [4]. In addition, many properties are significantly correlated or anti-correlated: peak flux, duration, fluence, hardness, asymmetry, and lag [5]. Each burst is defined by its duration T90, or the time to accumulate between 5% and 95% of the total photon counts [2]. Many long bursts (T90 > 2s) have multiple peaks, indicating short, overlapping pulses; however, there has been some disagreement as to whether these peaks are actually separate pulses or are just different propagations of the same pulse (see Fig. 1) [6]. By more closely analyzing doublepeaked bursts, questions regarding pulse emission mechanisms and GRB physics may see advancement.