The Swift Burst Analyser I: BAT and XRT spectral and flux evolution of Gamma Ray Bursts

TL;DR

This paper introduces software that converts Swift BAT and XRT count-rate data into accurate flux light curves by accounting for spectral evolution, enhancing the analysis of Gamma Ray Bursts.

Contribution

The paper presents a novel method and software for producing evolution-aware flux light curves from Swift data, improving upon standard count-rate based analyses.

Findings

Flux light curves are automatically generated and updated for all Swift GRBs.

Spectral evolution is effectively tracked using hardness ratios.

The tool enhances the accuracy of GRB spectral and flux analysis.

Abstract

Context: Gamma Ray Burst models predict the broadband spectral evolution and the temporal evolution of the energy flux. In contrast, standard data analysis tools and data repositories provide count-rate data, or use single flux conversion factors for all of the data, neglecting spectral evolution. Aims: To produce Swift BAT and XRT light curves in flux units, where the spectral evolution is accounted for. Methods: We have developed software to use the hardness ratio information to track spectral evolution of GRBs, and thus to convert the count-rate light curves from the BAT and XRT instruments on Swift into accurate, evolution-aware flux light curves. Results: The Swift Burst Analyser website (http://www.swift.ac.uk/burst_analyser) contains BAT, XRT and combined BAT-XRT flux light curves in three energy regimes for all GRBs observed by the Swift satellite. These light curves are automatically built and updated when data become available, are presented in graphical and plain-text format, and are available for download and use in research.