Journal Article

PUBDB-2022-02582

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Effective Shielding of ≲ 10 GeV Cosmic Rays from DenseMolecular Clumps

Yang, R.-z. (Corresponding author) ; Li, G.-X. ; Cui, Y.-D. ; de Ona Wilhelmi, E. M.Extern*DESY* ; Liu, B. ; Aharonian, F.

2023
Nature Publishing Group London

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Please use a persistent id in citations: doi:10.1038/s41550-022-01868-9  doi:10.3204/PUBDB-2022-02582

Report No.: arXiv:2301.06716

Abstract: The density of cosmic rays inside molecular clouds determines the ionization rate in the dense cores where stars form. It is also one of the drivers of astrochemistry leading to the creation of complex molecules. Through Fermi Large Area Telescope observations of nearby giant molecular clouds, we observed deficits (holes) in the gamma-ray residual map when modelling with the expected gamma-ray diffuse emission from uniform cosmic rays interacting with the molecular content. We propose that the deficit is due to the lack of penetration of the low-energy (sub-GeV to GeV) cosmic rays into denser regions or clumps. This differs from the prevailing view of fast cosmic ray transport in giant molecular clouds where the magnetic turbulence is suppressed by neutral-ion damping, as our results require a slow diffusion inside dense molecular clumps. Through modelling we find that while the shielding is negligible on the cloud scale, it becomes important in the denser, parsec-sized regions where the gravitational collapse is already at play, changing the initial condition of star formation and astrochemistry.

Note: Nat Astron (2023). Published in Nature Astronomy

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Contributing Institute(s):

1. Gammaastronomie (Z_GA)

Research Program(s):

1. 613 - Matter and Radiation from the Universe (POF4-613) (POF4-613)

Experiment(s):

1. The Fermi Large Area Telescope

Appears in the scientific report 2023

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Database coverage:
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