What does "spectral hardness" mean?
Context, this abstract snippet: "Here, we show that a short gamma-ray burst (GRB) in our Galaxy
is consistent with all observables: Such an event is sufficiently short and provides the
necessary energy in the relevant spectral range of γ-rays. Its spectral hardness is
consistent with the differential production rates of 14C and 10Be as observed. T"
Google wasn't very illuminating....