摘要：We present a new algorithm for reconstructing the Galactic free electron density from
pulsar dispersion measures. The algorithm performs a nonparametric tomography for a
density field with an arbitrary amount of degrees of freedom. It is based on approximating
the Galactic free electron density as the product of a profile function with a
statistically isotropic and homogeneous log-normal field. Under this approximation the
algorithm generates a map of the free electron density as well as an uncertainty estimate
without the need of information about the power spectrum. The uncertainties of the pulsar
distances are treated consistently by an iterative procedure. We tested the algorithm
using the NE2001 model with modified fluctuations as a Galaxy model, pulsar populations
generated from the Lorimer population model, and mock observations emulating the upcoming
Square Kilometer Array (SKA). We show the quality of the reconstruction for mock data sets
containing between 1000 and 10 000 pulsars with distance uncertainties of up to 25%. Our
results show that with the SKA nonparametric tomography of the Galactic free electron
density becomes feasible, but the quality of the reconstruction is very sensitive to the
distance uncertainties.
关键词：Galaxy: structure;ISM: structure;pulsars: general
