Astronomy and Astrophysics – Astrophysics
Scientific paper
2008-09-01
Astronomy and Astrophysics
Astrophysics
Accepted for publication in MNRAS Letters
Scientific paper
10.1111/j.1745-3933.2008.00570.x
Using a one-dimensional $\alpha\omega$-dynamo model appropriate to galaxies, we study the possibility of dynamo action driven by a stochastic alpha effect and shear. To determine the field evolution, one needs to examine a large number of different realizations of the stochastic component of $\alpha$. The net growth or decay of the field depends not only on the dynamo parameters but also on the particular realization, the correlation time of the stochastic $\alpha$ compared to turbulent diffusion timescale and the time over which the system is evolved. For dynamos where both a coherent and fluctuating $\alpha$ are present, the stochasticity of $\alpha$ can help alleviate catastrophic dynamo quenching, even in the absence of helicity fluxes. One can obtain final field strengths up to a fraction $\sim 0.01$ of the equipartition field $ B_{eq}$ for dynamo numbers $| D| \sim 40$, while fields comparable to $ B_{eq}$ require much larger degree of $\alpha$ fluctuations or shear. This type of dynamo may be particularly useful for amplifying fields in the central regions of disk galaxies.
Subramanian Kandaswamy
Sur Sharanya
No associations
LandOfFree
Galactic dynamo action in presence of stochastic alpha and shear does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Galactic dynamo action in presence of stochastic alpha and shear, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Galactic dynamo action in presence of stochastic alpha and shear will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-60424