Issue |
A&A
Volume 695, March 2025
|
|
---|---|---|
Article Number | A148 | |
Number of page(s) | 17 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361/202452943 | |
Published online | 18 March 2025 |
An analytical model for the magnetic field in the thick shell of Galactic bubbles with uniform initial conditions
1
Université Libre de Bruxelles,
Science Faculty CP230,
1050
Brussels, Belgium
2
Institut für Astroteilchenphysik, Karlsruher Institut für Technologie,
Karlsruhe
76344, Germany
3
Institutt for fysikk, Norwegian University of Science and Technology (NTNU),
Trondheim, Norway
★ Corresponding author; vincent.pelgrims@ulb.be
Received:
9
November
2024
Accepted:
19
February
2025
Bubbles and super-bubbles are ubiquitous in the interstellar medium and influence their local magnetic field. Starting from the assumption that bubbles result from violent explosions that sweep matter away in a thick shell, we derived the analytical equations for the divergence-free, regular magnetic field in the shell. The explosion velocity field is assumed to be radial but not necessarily spherical, making it possible to model various-shaped bubbles. Assuming an explosion center, the magnetic field at the present time is fully determined by the initial uniform magnetic field, the present-time geometry of the bubble shell, and a radial vector field that encodes the explosion-induced displacement of matter, from its original location to its present-time location. We presented the main characteristics of our magnetic-field model using a simple linear model for the radial displacements. Next, we used our analytical prescription, informed by a three-dimensional dust density map, to estimate the expected contribution of the shell of the Local Bubble, the super-bubbles in which the Sun resides, to the integrated Faraday rotation measures and synchrotron emission and to compare these to full-sky observational data. We found that, while the contribution to the former is minimal, the contribution to the latter is very significant at Galactic latitudes |b| > 45°. Our results underline the need to take the Local Bubble into account in large-scale Galactic magnetic field studies.
Key words: polarization / ISM: bubbles / dust, extinction / ISM: magnetic fields / ISM: supernova remnants / solar neighborhood
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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