Efficient highly-subsonic turbulent dynamo and growth of primordial magnetic fields. (arXiv:2101.08256v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Chirakkara_R/0/1/0/all/0/1">Radhika Achikanath Chirakkara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Federrath_C/0/1/0/all/0/1">Christoph Federrath</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Trivedi_P/0/1/0/all/0/1">Pranjal Trivedi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Banerjee_R/0/1/0/all/0/1">Robi Banerjee</a>

We present the first study on the amplification of magnetic fields by the
turbulent dynamo in the highly subsonic regime, with Mach numbers ranging from
$10^{-3}$ to $0.4$. We find that for the lower Mach numbers the saturation
efficiency of the dynamo, $(E_{mathrm{mag}}/E_{mathrm{kin}})_{mathrm{sat}}$,
increases as the Mach number decreases. Even in the case when injection of
energy is purely through longitudinal forcing modes,
$(E_{mathrm{mag}}/E_{mathrm{kin}})_{mathrm{sat}}$ $gtrsim 10^{-2}$ at a
Mach number of $10^{-3}$. We apply our results to magnetic field amplification
in the early Universe and predict that a turbulent dynamo can amplify
primordial magnetic fields to $gtrsim$ $10^{-16}$ Gauss on scales up to 0.1 pc
and $gtrsim$ $10^{-13}$ Gauss on scales up to 100 pc. This produces fields
compatible with lower limits of the intergalactic magnetic field inferred from
blazar $gamma$-ray observations.

We present the first study on the amplification of magnetic fields by the
turbulent dynamo in the highly subsonic regime, with Mach numbers ranging from
$10^{-3}$ to $0.4$. We find that for the lower Mach numbers the saturation
efficiency of the dynamo, $(E_{mathrm{mag}}/E_{mathrm{kin}})_{mathrm{sat}}$,
increases as the Mach number decreases. Even in the case when injection of
energy is purely through longitudinal forcing modes,
$(E_{mathrm{mag}}/E_{mathrm{kin}})_{mathrm{sat}}$ $gtrsim 10^{-2}$ at a
Mach number of $10^{-3}$. We apply our results to magnetic field amplification
in the early Universe and predict that a turbulent dynamo can amplify
primordial magnetic fields to $gtrsim$ $10^{-16}$ Gauss on scales up to 0.1 pc
and $gtrsim$ $10^{-13}$ Gauss on scales up to 100 pc. This produces fields
compatible with lower limits of the intergalactic magnetic field inferred from
blazar $gamma$-ray observations.

http://arxiv.org/icons/sfx.gif