Multidimensional analysis of Fermi GBM gamma-ray bursts
  The Fermi GBM catalog provides a large database with many measured variables
that can be used to explore and verify gamma-ray burst classification results.
We have used Principal Component Analysis and statistical clustering techniques
to look for clustering in a sample of 801 gamma-ray bursts described by sixteen
classification variables. The analysis recovers what appears to be the Short
class and two long-duration classes that differ from one another via peak flux,
with negligible variations in fluence, duration and spectral hardness. Neither
class has properties entirely consistent with the Intermediate GRB class.
Spectral hardness has been a critical Intermediate class property. Rather than
providing spectral hardness, Fermi GBM provides a range of fitting variables
for four different spectral models; it is not intuitive how these variables can
be used to support or disprove previous GRB classification results.
