Spectral Lag Relations in GRB Pulses Detected with HETE-2

TL;DR

This study analyzes spectral lags in gamma-ray bursts using HETE-2 data, revealing correlations with luminosity, pulse duration, and peak energy, and confirming the validity of BATSE relations at lower energies.

Contribution

It introduces a pulse-fit method to investigate spectral lags in GRBs at lower energies, confirming known correlations and supporting the curvature effect model.

Findings

Spectral lag correlates with luminosity, pulse duration, and Epeak.

BATSE correlations hold at 6-25 keV energies.

Photon energy dependence explains the curvature effect model.

Abstract

Using a pulse-fit method, we investigate the spectral lags between the traditional gamma-ray band (50-400 keV) and the X-ray band (6-25 keV) for 8 GRBs with known redshifts (GRB 010921, GRB 020124, GRB 020127, GRB 021211, GRB 030528, GRB 040924, GRB 041006, GRB 050408) detected with the WXM and FREGATE instruments aboard the HETE-2 satellite. We find several relations for the individual GRB pulses between the spectral lag and other observables, such as the luminosity, pulse duration, and peak energy (Epeak). The obtained results are consistent with those for BATSE, indicating that the BATSE correlations are still valid at lower energies (6-25 keV). Furthermore, we find that the photon energy dependence for the spectral lags can reconcile the simple curvature effect model. We discuss the implication of these results from various points of view.