Voyager 1 Data Reveals Signatures of the Local Gas and Cosmic-Ray Source Distributions
Authors
Troy A. Porter, Igor V. Moskalenko, Alan C. Cummings, Guðlaugur Jóhannesson
Categories
Abstract
We investigate the effects of the nearby interstellar medium (ISM) on the locally measured cosmic-ray (CR) spectra. Using the GALPROP code we explore how variations in the local gas and source distributions affect spectral features at low energies. Comparing with recent Voyager 1 data taken in the local ISM, we show that for a realistic interstellar gas distribution, the nearest source of the low energy CR particles observed nearby the Solar system is constrained to be within the range ~150-200 pc distant. We find that the modelling supports the conclusion of Cummings et al. (2025) that there is a significant fraction of primary Boron in its observed spectrum at low energies. Our study shows that detailed modelling of the immediate Galactic environment is required to robustly infer Galactic CR propagation parameters from local measurements, and that accounting for nearby ISM structure can alleviate tensions between direct CR data and global propagation models.
Voyager 1 Data Reveals Signatures of the Local Gas and Cosmic-Ray Source Distributions
Categories
Abstract
We investigate the effects of the nearby interstellar medium (ISM) on the locally measured cosmic-ray (CR) spectra. Using the GALPROP code we explore how variations in the local gas and source distributions affect spectral features at low energies. Comparing with recent Voyager 1 data taken in the local ISM, we show that for a realistic interstellar gas distribution, the nearest source of the low energy CR particles observed nearby the Solar system is constrained to be within the range ~150-200 pc distant. We find that the modelling supports the conclusion of Cummings et al. (2025) that there is a significant fraction of primary Boron in its observed spectrum at low energies. Our study shows that detailed modelling of the immediate Galactic environment is required to robustly infer Galactic CR propagation parameters from local measurements, and that accounting for nearby ISM structure can alleviate tensions between direct CR data and global propagation models.
Authors
Troy A. Porter, Igor V. Moskalenko, Alan C. Cummings et al. (+1 more)
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