A Search for Structure in Gamma Ray Burst X-Ray Flares Confirming Whether They are Similar to the Three Pulse Structure Found in Prompt Emission Pulses

Undergraduate #279
Discipline: Physics
Subcategory: Astronomy and Astrophysics

Jason Baron - University of the Virgin Islands
Co-Author(s): Judith Racusin, NASA/GSFC Code 661 David Morris, University of the Virgin Islands

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Gamma Ray Bursts (GRBs) are the most luminous electromagnetic events known to occur throughout the Universe. These violent explosions produce relativistic jets in a short burst of prompt emission and are followed by an afterglow emitted across the electromagnetic spectrum. During the afterglow, there are periods of sporadic increase in the X-ray flux, known as flares. Only ~1/2 of all GRBs produce flares. We present a sample selection of the brightest isolated flares observed by the Swift X-Ray Telescope (XRT). Using light curves from the XRT Team repository at the University of Leicester between 2005 and 2014, and our own light curve fits, the sample was filtered using a stringent set of criteria. We selected bursts that: 1) had a high peak flare flux to afterglow ratio, and/or 2) a high fluence (integrated flux). By further analyzing these flares, we plan to study the underlying structure of flares, searching for the three components that have been seen in isolated prompt emission pulses: an initial small rapidly decaying pulse, followed by the main flare which then decays over time and is finally followed by another small but slower decaying pulse. Seeing a similar behavior in X-ray flares as we see in prompt pulses will tell us about the physics of relativistic shocks.

Funder Acknowledgement(s): NASA Grant NNX13AD28A

Faculty Advisor: David Morris,