摘要：Context. The determination of meteoroid mass indices is central to flux
measurements and evolutionary studies of meteoroid populations. However, different authors
use different approaches to fit observed data, making results difficult to reproduce and
the resulting uncertainties difficult to justify. The real, physical, uncertainties are
usually an order of magnitude higher than the reported values.
Aims. We aim to develop a fully automated method that will measure
meteoroid mass indices and associated uncertainty. We validate our method on large radar
and optical datasets and compare results to obtain a best estimate of the true meteoroid
mass index.
Methods. Using MultiNest, a Bayesian inference tool that calculates the
evidence and explores the parameter space, we search for the best fit of cumulative number
vs. mass distributions in a four-dimensional space of variables (a,b,X1,X2).
We explore biases in meteor echo distributions using optical meteor data as a calibration
dataset to establish the systematic offset in measured mass index values.
Results. Our best estimate for the average de-biased mass index for the
sporadic meteoroid complex, as measured by radar appropriate to the mass range
10-3 > m >
10-5 g, was s = −2.10 ± 0.08. Optical data in the
10-1 > m >
10-3 g range, with the shower meteors removed, produced
s = −2.08 ±
0.08. We find the mass index used by Grün et al. (1985) is substantially larger than we measure in the
10-4 < m <
10-1 g range.
