Honors College Thesis

 

The lag–luminosity correlation in time-resolved episodes of long gamma-ray bursts Öffentlichkeit Deposited

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https://ir.library.oregonstate.edu/concern/honors_college_theses/d217qr52j

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  • We present an analysis of the relationship between spectral lag and luminosity in time-resolved segments of long gamma-ray bursts detected by BATSE, an experiment aboard the Compton Gamma Ray Observatory satellite. For full bursts, there is a well-established correlation between the lag, which is easily computed, and the total burst luminosity, which is often difficult to determine. We investigate the possibility that this lag–luminosity relationship extends to intervals and pulses within a burst. This is motivated by the complex time profile of many bursts, which can involve high variability (“spikiness”) and distinct multi-pulse structures. To measure time-resolved lags, we perform cross-correlation analysis on slices of light curves selected with a Gaussian filter tuned either to isolate distinct pulses where present or otherwise partition the burst evenly. Taking peak count rate as a proxy for luminosity, we fit a power-law to the lag–luminosity data of slices within each burst. In a sample of 31 bursts, we find a weighted mean power law index of -0.117 ± 0.052, with a more significant mean of -0.455 ± 0.071 appearing in the subset of bursts with distinguishable pulse events. We also observe a strong positive correlation in a set of bursts with precursor events, but refrain from drawing conclusions due to the size of that sample. Our results suggest the possibility of a time-resolved lag–luminosity correlation, especially in the population of bursts consisting of multiple distinct emission events. The power of this evidence is limited by sample size, but encourages further work on a larger sample of more recent data. If it exists, such an intra-burst lag correlation would help validate the correlation across full bursts, since it is less affected by selection effects. Key Words: spectral lag, gamma-ray bursts, high-energy astrophysics
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