Study Suggests Galactic Center Filaments May Form from Turbulence Rather Than Known Cosmic Ray Sources
A new preprint study using magnetohydrodynamics simulations finds little observable difference between two leading theories for the origin of nonthermal filaments at the Galactic Center, prompting the authors to propose a third mechanism involving intermittent turbulence structures. These filaments — elongated, synchrotron-emitting structures tens of parsecs long — have long puzzled astronomers, with competing theories attributing them to pulsar wind nebulae jets or interstellar shock acceleration. The findings suggest current models may be insufficient to explain the filaments and that Galactic Center turbulence deserves serious consideration as a formation pathway.
Researchers have submitted a study to The Astrophysical Journal presenting magnetohydrodynamics (MHD) simulations of cosmic ray propagation in the Galactic Center, aimed at distinguishing between two proposed origins for nonthermal filaments (NTFs): a lepton-dominated mechanism driven by pulsar wind nebulae jets, and a proton-dominated mechanism driven by interstellar shock acceleration. Using the Athena++ MHD code — modified to incorporate radiative and collisional losses — the team varied magnetic field strength, plasma density, and cosmic ray diffusion coefficients to assess how Galactic Center conditions affect cosmic ray propagation, plasma heating, and synchrotron emission. Across these parameter variations, the simulations revealed few observable differences between the lepton- and proton-dominated scenarios, making it difficult to discriminate between the two mechanisms on the basis of current observational data. Comparing the simulation outputs against observed filament properties, the authors argue that neither existing mechanism fully accounts for the NTFs, motivating a third hypothesis: that the filaments arise from intermittent turbulent structures within the Galactic Center environment. The paper is 17 pages with 11 figures and is currently a preprint, pending peer review.
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The study is a preprint and has not yet undergone peer review.
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- arXiv astro-phCenter
Rhea-RT: Dynamical impact of Central Molecular Zone conditions on the properties of the interstellar medium and stellar feedback coupling
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