TY - JOUR
T1 - Gravito-turbulence and dynamo in poorly ionized protostellar discs-I. Zero-net-flux case
AU - Riols, A.
AU - Xu, W.
AU - Lesur, G.
AU - Kunz, M. W.
AU - Latter, H.
N1 - Publisher Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2021/9/1
Y1 - 2021/9/1
N2 - In their early stages, protoplanetary discs are sufficiently massive to undergo gravitational instability (GI). This instability is thought to be involved in mass accretion, planet formation via gas fragmentation, the generation of spiral density waves, and outbursts. A key and very recent area of research is the interaction between the GI and magnetic fields in young protoplanetary discs, in particular whether this instability is able to sustain a magnetic field via a dynamo. We conduct 3D, stratified shearing-box simulations using two independent codes, PLUTO and Athena++, to characterize the GI dynamo in poorly ionized protostellar discs subject to ambipolar diffusion. We find that the dynamo operates across a large range of ambipolar Elssaser number Am (which characterizes the strength of ambipolar diffusion) and is particularly strong in the regime Am = 10-100, with typical magnetic to thermal energy ratios of order unity. The dynamo is only weakly dependent on resolution (at least for Am ≲ 100), box size, and cooling law. The magnetic field is produced by the combination of differential rotation and large-scale vertical roll motions associated with spiral density waves. Our results have direct implications for the dynamo process in young protoplanetary discs and possibly some regions of active galactic nucleus discs.
AB - In their early stages, protoplanetary discs are sufficiently massive to undergo gravitational instability (GI). This instability is thought to be involved in mass accretion, planet formation via gas fragmentation, the generation of spiral density waves, and outbursts. A key and very recent area of research is the interaction between the GI and magnetic fields in young protoplanetary discs, in particular whether this instability is able to sustain a magnetic field via a dynamo. We conduct 3D, stratified shearing-box simulations using two independent codes, PLUTO and Athena++, to characterize the GI dynamo in poorly ionized protostellar discs subject to ambipolar diffusion. We find that the dynamo operates across a large range of ambipolar Elssaser number Am (which characterizes the strength of ambipolar diffusion) and is particularly strong in the regime Am = 10-100, with typical magnetic to thermal energy ratios of order unity. The dynamo is only weakly dependent on resolution (at least for Am ≲ 100), box size, and cooling law. The magnetic field is produced by the combination of differential rotation and large-scale vertical roll motions associated with spiral density waves. Our results have direct implications for the dynamo process in young protoplanetary discs and possibly some regions of active galactic nucleus discs.
KW - dynamo
KW - instabilities
KW - protoplanetary discs
KW - turbulence
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U2 - 10.1093/mnras/stab1637
DO - 10.1093/mnras/stab1637
M3 - Article
AN - SCOPUS:85127737073
SN - 0035-8711
VL - 506
SP - 1407
EP - 1426
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -