ON THE ELECTRON ENERGY DISTRIBUTION INDEX OF SWIFT GAMMA-RAY BURST AFTERGLOWS


Curran P. A., Evans P. A., DE PASQUALE M., Page M. J., van der Horst A. J.

ASTROPHYSICAL JOURNAL LETTERS, vol.716, no.2, 2010 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 716 Issue: 2
  • Publication Date: 2010
  • Doi Number: 10.1088/2041-8205/716/2/l135
  • Journal Name: ASTROPHYSICAL JOURNAL LETTERS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Keywords: acceleration of particles, gamma-ray burst: general, methods: statistical, radiation mechanisms: non-thermal, shock waves, ULTRARELATIVISTIC SHOCK-WAVES, PARTICLE-ACCELERATION, RELATIVISTIC SHOCKS, FERMI ACCELERATION, LIGHT CURVES, JETS, ENVIRONMENT, SPECTRA, GRBS
  • Istanbul University Affiliated: Yes

Abstract

The electron energy distribution index, p, is a fundamental parameter of the synchrotron emission from a range of astronomical sources. Here we examine one such source of synchrotron emission, gamma-ray burst (GRB) afterglows observed by the Swift satellite. Within the framework of the blast wave model, we examine the constraints placed on the distribution of p by the observed X-ray spectral indices and parameterize the distribution. We find that the observed distribution of spectral indices are inconsistent with an underlying distribution of p composed of a single discrete value but consistent with a Gaussian distribution centered at p = 2.36 and having a width of 0.59. Furthermore, accepting that the underlying distribution is a Gaussian, we find that the majority (greater than or similar to 94%) of GRB afterglows in our sample have cooling break frequencies less than the X-ray frequency.