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Unraveling the origin of magnetic fields in galaxies

Abstract:
Despite their ubiquity, there are many open questions regarding galactic and cosmic magnetic fields. Specifically, current observational constraints cannot rule out whether magnetic fields observed in galaxies were generated in the early Universe or are of astrophysical nature. Motivated by this, we use our magnetic tracer algorithm to investigate whether the signatures of primordial magnetic fields persist in galaxies throughout cosmic time. We simulate a Milky Way-like galaxy down to z ∼ 2–1 in four scenarios: magnetized solely by primordial magnetic fields, magnetized exclusively by supernova (SN)-injected magnetic fields, and two combined primordial + SN magnetization cases. We find that once primordial magnetic fields with a comoving strength B0 > 10−12 G are considered, they remain the primary source of galaxy magnetization. Our magnetic tracers show that, even combined with galactic sources of magnetization, when primordial magnetic fields are strong, they source the large-scale fields in the warm metal-poor phase of the simulated galaxy. In this case, the circumgalactic medium and intergalactic medium can be used to probe B0 without risk of pollution by magnetic fields originated in the galaxy. Furthermore, whether magnetic fields are primordial or astrophysically sourced can be inferred by studying local gas metallicity. As a result, we predict that future state-of-the-art observational facilities of magnetic fields in galaxies will have the potential to unravel astrophysical and primordial magnetic components of our Universe.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1093/mnras/stab968

Authors


More by this author
Institution:
University of Oxford
Department:
PHYSICS
Sub department:
Physics - Central
Oxford college:
Christ Church
Role:
Author
ORCID:
0000-0002-4059-9850
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Astrophysics
Role:
Author


Publisher:
Oxford University Press
Journal:
Monthly Notices of the Royal Astronomical Society More from this journal
Volume:
504
Issue:
2
Article number:
2517–2534
Publication date:
2021-04-09
Acceptance date:
2021-04-01
DOI:
EISSN:
1365-2966
ISSN:
035-8711


Language:
English
Keywords:
Pubs id:
1147865
Local pid:
pubs:1147865
Deposit date:
2021-02-22

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