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Dust in the Wind with Resonant Drag Instabilities: I. The Dynamics of Dust-Driven Outflows in GMCs and HII Regions

Hopkins, Philip F. and Rosen, Anna L. and Squire, Jonathan and Panopoulou, Georgia V. and Soliman, Nadine H. and Seligman, Darryl and Steinwandel, Ulrich P. (2021) Dust in the Wind with Resonant Drag Instabilities: I. The Dynamics of Dust-Driven Outflows in GMCs and HII Regions. . (Unpublished)

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Radiation-dust driven outflows, where radiation pressure on dust grains accelerates gas, occur in many astrophysical environments. Almost all previous numerical studies of these systems have assumed that the dust was perfectly-coupled to the gas. However, it has recently been shown that the dust in these systems is unstable to a large class of 'resonant drag instabilities' (RDIs) which de-couple the dust and gas dynamics and could qualitatively change the nonlinear outcome of these outflows. We present the first simulations of radiation-dust driven outflows in stratified, inhomogeneous media, including explicit grain dynamics and a realistic spectrum of grain sizes and charge, magnetic fields and Lorentz forces on grains (which dramatically enhance the RDIs), Coulomb and Epstein drag forces, and explicit radiation transport allowing for different grain absorption and scattering properties. In this paper we consider conditions resembling giant molecular clouds (GMCs), HII regions, and distributed starbursts, where optical depths are modest (≲1), single-scattering effects dominate radiation-dust coupling, Lorentz forces dominate over drag on grains, and the fastest-growing RDIs are similar, such as magnetosonic and fast-gyro RDIs. These RDIs generically produce strong size-dependent dust clustering, growing nonlinear on timescales that are much shorter than the characteristic times of the outflow. The instabilities produce filamentary and plume-like or 'horsehead' nebular morphologies that are remarkably similar to observed dust structures in GMCs and HII regions. Additionally, in some cases they strongly alter the magnetic field structure and topology relative to filaments. Despite driving strong micro-scale dust clumping which leaves some gas 'behind,' an order-unity fraction of the gas is always efficiently entrained by dust.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper ItemGIZMO code
Hopkins, Philip F.0000-0003-3729-1684
Rosen, Anna L.0000-0003-4423-0660
Squire, Jonathan0000-0001-8479-962X
Panopoulou, Georgia V.0000-0001-7482-5759
Seligman, Darryl0000-0002-0726-6480
Steinwandel, Ulrich P.0000-0001-8867-5026
Additional Information:Support for PFH was provided by NSF Research Grants 1911233 & 20009234, NSF CAREER grant 1455342, NASA grants 80NSSC18K0562, HST-AR-15800.001-A. Numerical calculations were run on the Caltech compute cluster “Wheeler,” allocations FTA-Hopkins supported by the NSF and TACC, and NASA HEC SMD-16-7592. Support for ALR was provided by the Institute for Theory & Computation at Harvard University. ALR would also like to thank her “coworker” Nova Rosen, for “insightful conversations” and unwavering support at home while this paper was being written during the Coronavirus pandemic of 2020/2021. Her contribution was not sufficient to warrant co-authorship due to excessive napping. DATA AVAILABILITY STATEMENT. The data supporting the plots within this article are available on reasonable request to the corresponding author. A public version of the GIZMO code is available at
Group:Astronomy Department, TAPIR
Funding AgencyGrant Number
Harvard UniversityUNSPECIFIED
Subject Keywords:instabilities — turbulence — ISM: kinematics and dynamics — star formation: general — galaxies: formation — dust, extinction
Record Number:CaltechAUTHORS:20220228-183241907
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113642
Deposited By: George Porter
Deposited On:01 Mar 2022 18:33
Last Modified:01 Mar 2022 18:33

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