3D evolution of barred galaxies based on the cosmic-ray driven dynamo
Abstract
Our MHD numerical calculations provide results for a three-dimensional model of barred galaxies involving a cosmic-ray driven dynamo process that depends on star formation rates. We applied global 3D numerical calculations of a cosmic-ray driven dynamo in barred galaxies with different physical input parameters such as the supernova (SN) rate.Furthermore, we argue that the cosmic-ray driven dynamo can account for a number of magnetic features in barred galaxies, such as magnetic arms observed along the gaseous arms, magnetic arms in the inter-arm regions, polarized emission that is at the strongest in the central part of the galaxy, where the bar is situated, polarized emission that forms ridges coinciding with the dust lanes along the leading edges of the bar, as well as their very strong total radio intensity. Our results give the modelled magnetic field topology similar to the observational maps of polarized intensity in barred galaxies. Moreover, they cast a new light on a number of polarization properties observed in barred or even spiral galaxies, like fast exponential growth of the total magnetic energy to the present values, stochastic nature of magnetic field reversals (for instance: in the Milky Way).We concluded that a cosmic-ray driven dynamo process in barred galaxies could boost magnetic fields efficiently. The fastest rate of magnetic field increase is 195 yr for SN frequency 1/50 yr-1.The obtained intensity of magnetic field corresponds to the observational values (few μG in spiral arms). We also found the effect of shifting magnetic arms.
- Publication:
-
IAU General Assembly
- Pub Date:
- August 2015
- Bibcode:
- 2015IAUGA..2252638N