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Table 1

Characteristic quantities of the small-scale dynamo for accretion-driven turbulence (left hand side) and for SN-driven turbulence (right hand side).

Accretion-driven dynamo SN-driven dynamo


Spherical galaxy Disk-shaped galaxy Spherical galaxy Disk-shaped galaxy

L 103 pc 2.4 × 102 pc 7.0 × 102 pc 2.4 × 102 pc
V 3.7 km s-1 9.7 km s-1 47 km s-1 61 km s-1
Re 1.3 × 1011 8.1 × 1010 1.2 × 1012 5.1 × 1011
Rm 3.0 × 1025 1.9 × 1025 2.7 × 1026 1.2 × 1026
ν 1.1 × 10-5 pc 3.8 × 10-6 pc 1.7 × 10-6 pc 1.0 × 10-6 pc
Γ 1.5 × 102 Myr-1 1.4 × 103 Myr-1 7.1 × 103 Myr-1 1.9 × 104 Myr-1
t ν 1.7 × 10-1 Myr 1.9 × 10-2 Myr 3.8 × 10-3 Myr 1.5 × 10-3 Myr
t L 2.7 × 102 Myr 24 Myr 15 Myr 3.8 Myr
B sat 1.1 × 10-9 G 3.3 × 10-9 G 7.5 × 10-9 G 1.2 × 10-8 G
B sat,L 1.6 × 10-6 G 4.3 × 10-6 G 2.1 × 10-5 G 2.7 × 10-5 G

Notes. For each case of turbulence forcing we present results for a spherical galaxy and a disk-shaped galaxy. We list the forcing scale of the turbulence L, the typical turbulent velocity on that scale V, the hydrodynamic and magnetic Reynolds numbers Re and Rm, the viscous scale ν, the kinematic growth rate of the dynamo Γ, the time until saturation on the viscous and the forcing scale occurs t and tL and the saturation field strengths on those scales Bsat and Bsat,L. All the given values in this table are for the fiducial model with a factor β = 0.05 of kinetic energy that goes into turbulent motions and a SN efficiency of α = 0.01.

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