Curvature Effect of a Non-Power-Law Spectrum and Spectral Evolution of GRB X-Ray Tails

Abstract

The apparent spectral evolution observed in the steep decay phase of many GRB early afterglows raises a great concern of the high-latitude "curvature effect" interpretation of this phase. However, previous curvature effect models only invoked a simple power law spectrum upon the cessation of the prompt internal emission. We investigate a model that invokes the "curvature effect" of a more general non-power-law spectrum and test this model with the Swift/XRT data of some GRBs. We show that one can reproduce both the observed lightcurve and the apparent spectral evolution of several GRBs using a model invoking a power-law spectrum with an exponential cut off. GRB 050814 is presented as an example.

12 pages, 4 figures, 1 table, . Accepted for publication in ApJ Letters

References in corpus (6)

• A Comprehensive Analysis of the Swift/XRT Data: II. Diverse Physical Origins of the Shallow Decay Segment
• A comprehensive analysis of Swift/XRT data: I. Apparent spectral evolution of GRB X-ray tails
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• Swift captures the spectrally evolving prompt emission of GRB 070616
• The full curvature effect expected in early X-ray afterglow emission of gamma-ray bursts
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