ORIGAMI · The origin of the Galactic magnetic field
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2017-06-01 → 2019-11-29
- EU contribution
- €152,653
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
The origin of the Galactic magnetic field
Magnetic fields can affect the evolution of turbulence, the flux of cosmic rays, the formation of the cold molecular gas, and the evolution of feedback regions; in essence, magnetic fields can affect all the internal processes that redistribute mass, energy, and momentum in a galaxy. However, the value and the morphology of the interstellar magnetic field are largely unknown, because the observational methods available to measure it are inherently uncertain. Without a theoretical understanding of the history of the Galactic magnetic field and the complex interactions between the phases of the ISM, even the most accurate and complete observational studies remain inconclusive. It is the main objective of ORIGAMI to provide the theoretical foundations for a comprehensive understanding of galactic magnetic fields. The most widely accepted theory for the growth and the long-term evolution of the galactic magnetic field is the galactic dynamo. In this scenario, primordial, tiny, seed magnetic fields grow inside a proto-galaxy as they are twisted by turbulence and differential rotation at large scales, and then re-ordered by diffusive reconnection at small scales. The primary goal of this project is to investigate the growth of the magnetic field through a galactic dynamo process, in the context of the current Galactic evolution models. In the course of ORIGAMI, we developed numerical techniques that produced a groundbreaking result: the first direct, multi-physics simulations of galactic dynamos. ORIGAMI has had a great impact on the community, the career of the ER, and the expertise of the host. It offered to the community the first global models of Milky-Way-like galaxies with magnetization that directly demonstrate a dynamo. This was the first discovery of a mean-field dynamo in multi-physics numerical simulations of spiral galaxies. These models will have a tremendous impact on observational campaigns. They are realizations of the galactic magnetic field that take into account the dynamical evolution of the galaxy and include the effects of stellar feedback. Therefore, they can be used to simulate the results of magnetic field observations in our galaxy and towards extragalactic sources. The fact that they represent an entire spiral galaxy also allows observers to test the effects of cosmic variance by changing the position of the observer.
Data: CORDIS, © European Union
Project objective
Magnetic fields lie at the heart of essentially all the outstanding problems in galactic evolution. However, the measurement of interstellar magnetic fields is very challenging. We can either measure the strength or the direction of the magnetic field vector in different regions of the Milky Way. Clearly, in order to assess the impact of the magnetic field in the core processes of galactic evolution, such as star formation and stellar feedback, we need to complement the observations with simulations of the magnetic field evolution.The most successful simulations of the galactic magnetic field evolution show that tiny magnetic seeds of cosmic origin were amplified to their current values through a dynamo process. In a dynamo, large-scale galactic processes such as differential rotation and turbulence twist magnetic field lines, and small-scale processes like Ohmic diffusion reconnect them. However, simulations of this process so far lack the simultaneous modeling of the processes that generate turbulence and the realistic small-scale diffusion that drives the dynamo.This ambitious project will develop the first simulations that will include all the core processes of galactic evolution, such as a multi-phase interstellar medium, time-dependent star formation and stellar feedback, and the realistic non-ideal MHD terms necessary for modeling a dynamo. The simulations will be performed with the RAMSES code, a throughly tested tool for galaxy evolution simulations. The Adaptive Mesh Refinement technique employed in the code will allow capturing the self-consistent generation of turbulence by stellar feedback, and its zoom-in capabilities will allow re-simulating regions of interest with enough resolution to model the magnetic field diffusion.The outcome will be the first self-consistent model of the Galactic magnetic field, an essential input for cosmological, galaxy-evolution, and star-formation theories, and a reference tool for observational studies.
Original text from CORDIS.
Participants
- IDRYMA TECHNOLOGIAS KAI EREVNAS · IRAKLEIOCoordinatorGreece
Links
Data: CORDIS, © European Union