GLOBAL SIMULATIONS OF THE MAGNETIC FIELD EVOLUTION IN BARRED GALAXIES UNDER THE INFLUENCE OF THE COSMIC-RAY-DRIVEN DYNAMO
- Astronomical Observatory, Jagiellonian University, ul Orla 171, 30-244 Krakow (Poland)
- Torun Centre for Astronomy, Nicolaus Copernicus University, 87-148 Torun/Piwnice (Poland)
We present three-dimensional global numerical simulations of the cosmic-ray (CR) driven dynamo in barred galaxies. We study the evolution of the interstellar medium of the barred galaxy in the presence of non-axisymmetric component of the potential, i.e., the bar. The magnetohydrodynamical dynamo is driven by CRs, which are continuously supplied to the disk by supernova (SN) remnants. No magnetic field is present at the beginning of simulations but one-tenth of SN explosions is a source of a small-scale randomly oriented dipolar magnetic field. In all models we assume that 10% of 10{sup 51} erg SN kinetic energy output is converted into CR energy. To compare our results directly with the observed properties of galaxies, we construct realistic maps of polarized radio emission. The main result is that the CR-driven dynamo can amplify weak magnetic fields up to a few {mu}G within a few Gyr in barred galaxies. The obtained e-folding time is equal to 300 Myr and the magnetic field reaches equipartition at time t {approx} 4.0 Gyr. Initially, the completely random magnetic field evolves into large-scale structures. An even (quadrupole-type) configuration of the magnetic field with respect to the galactic plane can be observed. Additionally, the modeled magnetic field configuration resembles maps of the polarized intensity observed in barred galaxies. Polarization vectors are distributed along the bar and between spiral arms. Moreover, the drift of magnetic arms with respect to the spiral pattern in the gas density distribution is observed during the entire simulation time.
- OSTI ID:
- 21562661
- Journal Information:
- Astrophysical Journal Letters, Vol. 733, Issue 2; Other Information: DOI: 10.1088/2041-8205/733/2/L18; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
Similar Records
DAMPING OF THE MILKY WAY BAR BY MANIFOLD-DRIVEN SPIRALS
Ab Initio Simulations of a Supernova-driven Galactic Dynamo in an Isolated Disk Galaxy