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dc.contributor.authorForgan, D. H.
dc.contributor.authorBonnell, I. A.
dc.identifier.citationForgan , D H & Bonnell , I A 2018 , ' Clumpy shocks as the driver of velocity dispersion in molecular clouds : the effects of self-gravity and magnetic fields ' , Monthly Notices of the Royal Astronomical Society , vol. 481 , no. 4 , pp. 4532-4541 .
dc.descriptionDHF and IAB gratefully acknowledge support from the ECOGAL project, grant agreement 291227, funded by the European Research Council under ERC-2011-ADG.en
dc.description.abstractWe revisit an alternate explanation for the turbulent nature of molecular clouds - namely, that velocity dispersions matching classical predictions of driven turbulence can be generated by the passage of clumpy material through a shock. While previous work suggested this mechanism can reproduce the observed Larson relation between velocity dispersion and size scale (σ ∝ LΓ with Γ ≈ 0.5), the effects of self-gravity and magnetic fields were not considered. We run a series of smoothed particle magnetohydrodynamics experiments, passing clumpy gas through a shock in the presence of a combination of self-gravity and magnetic fields.We find power-law relations between σ and L throughout, with indices ranging from Γ = 0.3-1.2. These results are relatively insensitive to the strength and geometry of magnetic fields, provided that the shock is relatively strong. Γ is strongly sensitive to the angle between the gas' bulk velocity, and the shock front and the shock strength (compared to the gravitational boundness of the pre-shock gas). If the origin of the σ-L relation is in clumpy shocks, deviations from the standard Larson relation constrain the strength and behaviour of shocks in spiral galaxies.
dc.relation.ispartofMonthly Notices of the Royal Astronomical Societyen
dc.subjectISM: cloudsen
dc.subjectISM: kinematics and dynamicen
dc.subjectISM: structureen
dc.subjectMethods: numericalen
dc.subjectQB Astronomyen
dc.subjectAstronomy and Astrophysicsen
dc.subjectSpace and Planetary Scienceen
dc.titleClumpy shocks as the driver of velocity dispersion in molecular clouds : the effects of self-gravity and magnetic fieldsen
dc.typeJournal articleen
dc.contributor.sponsorEuropean Research Councilen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.contributor.institutionUniversity of St Andrews. St Andrews Centre for Exoplanet Scienceen
dc.description.statusPeer revieweden

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