Validation of heliospheric modeling algorithms through pulsar observations I: Interplanetary scintillation-based tomography

Solar-wind 3-D reconstruction tomography based on interplanetary scintillation (IPS) studies provides fundamental information for space-weather forecasting models, and gives the possibility to determine heliospheric column densities. Here we compare the time series of Solar-wind column densities derived from long-term observations of pulsars, and the Solar-wind reconstruction provided by the UCSD IPS tomography. In particular, we analyze the 2016, 2017 and 2018 Solar passages of PSR J0034-0534, and the 2016 and 2018 Solar passages of PSR J1022 + 1001. The results show that, where the UCSD IPS tomography makes use of its most robust settings, the matches between the two techniques are characterized by Pearson's R coefficients ranging from 0.64 to 0.90, indicating a good level of agreement. This unique work represents a completely independent comparison and validation of these techniques to provide such measurements, and it strengthens confidence in the use of both in space-weather analyses applications.