Properties of Short Gamma-ray Burst Pulses from a BATSE TTE GRB Pulse Catalog

Abstract

We analyze pulse properties of Short gamma-ray bursts (GRBs) from a new catalog containing 434 pulses from 387 BATSE Time-Tagged Event (TTE) GRBs. Short GRB pulses exhibit correlated properties of duration, fluence, hardness, and amplitude, and they evolve hard-to-soft while undergoing similar triple-peaked light curves similar to those found in Long/Intermediate bursts. We classify pulse light curves using their temporal complexities, demonstrating that Short GRB pulses exhibit a range of complexities from smooth to highly variable. Most of the bright, hard, chaotic emission seen in complex pulses seems to represent a separate highly-variable emission component. Unlike Long/Intermediate bursts, as many as 90% of Short GRBs are single-pulsed. However, emission in Short multi-pulsed bursts is coupled such that the first pulse's duration is a predictor of both the interpulse separation and subsequent pulse durations. These results strongly support the idea that external shocks produce the prompt emission seen in Short GRBs. The similarities between the triple-peaked structures and spectral evolution of Long, Short, and Intermediate GRBs then suggests that external shocks are responsible for the prompt emission observed in all GRB classes. In addition to these findings, we identify a new type of gamma-ray transient in which peak amplitudes occur at the end of the burst rather than at earlier times. Some of these "Crescendo" bursts are preceded by rapid-fire "Staccato" pulses, whereas the remaining are preceded by a variable episode that could be unresolved staccato pulses.

Properties of Short GRB Pulses in the Fourth BATSE Catalog: Implications for the Structure and Evolution of the Jetted Outflows

“…One SP (#07427) and one DP (#00575) in our sample are two EE bursts from Hakkila et al (2018a) and Bostancı et al (2013). However, we cannot fit the EE episodes with the pulse model because of their low signal-to-noise as in Hakkila et al (2018a). In practice, the EE components are more readily perceived in Swift/BAT mask-tagged data for sGRBs, we have examined in details their temporal and spectral properties and possible connections with main peak episodes (Li et al (2020), in preparation).…”

“…For brighter sGRBs, the EE component is sometimes detectable above the background (Norris & Bonnell 2006). One SP (#07427) and one DP (#00575) in our sample are two EE bursts from Hakkila et al (2018a) and Bostancı et al (2013). However, we cannot fit the EE episodes with the pulse model because of their low signal-to-noise as in Hakkila et al (2018a).…”

“…Study of the prompt emission light-curve and the spectral evolutions can provide a good probe to learn about the nature of these problems. Many authors have investigated the pulse properties via different methods in the past decades years (e.g., Kouveliotou 1994;Quilligan et al 1999Quilligan et al , 2002Norris et al 1996Norris et al , 2005Norris et al , 2011Hakkila & Preece 2011Hakkila et al 2015Hakkila et al , 2018a. GRB temporal profiles are usually very various, irregular and complicated.…”

Time-reversed Gamma-Ray Burst Light-curve Characteristics as Transitions between Subluminal and Superluminal Motion

“…These analyses have identified "hard-to-soft" and "intensity tracking" behaviors (e.g., Wheaton et al (1973); Golenetskii et al (1983); Norris et al (1986); Paciesas et al (1992)), but this oversimplified bimodal classification scheme has been shown to represent a continuous range of behaviors (e.g., Kargatis et al (1994); Bhat et al (1994); Ford et al (1995); Borgonovo, & Ryde (2001)). Treating each GRB pulse as a structured episode rather than one in which pulses are statistically-significant intensity peaks, several studies (Liang & Kargatis 1996;Hakkila et al 2015Hakkila et al , 2018a have demonstrated that most pulses undergo and stretched at the time of reflection to show how well they match one another (the solid line represents the folded and stretched residuals preceding the time of reflection, while the dashed line represents the residuals following that time). The process used to identify time-reversality, as well as the fitted characteristics of this pulse, is described in Hakkila et al (2018b).…”

“…Figures 3 and 6 are oversimplifications meant to represent generic situations. There is a spread of these alignments (e.g., see Figure 19 in Hakkila et al (2018a)), and a prime example of a pulse in which these are offset is BATSE 143p1 (see Figure 1 in Hakkila et al (2018b)). In addition to this offset, pulse residuals are not always folded at the peak of the residual function; many pulses have time-reversed residual structures for which the time of reflection does not occur other at the maximum of the residual function (see Figures 14-16 in Hakkila et al (2018b)).…”