Numerical simulations of a shock-filament interaction

Pittard, J. M.; Goldsmith, Kathryn

doi:10.1093/mnras/stw378

Cited by 10 publications

(17 citation statements)

References 96 publications

(124 reference statements)

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“…It can be seen that, in general, the relative error decreases with increasing resolution, and thus manifests convergence. This is in line with the results from Pittard & Parkin (2015) and Pittard & Goldsmith (2016). Fig.…”

Section: Convergence Studiessupporting

confidence: 92%

“…The current study extends the purely hydrodynamic work conducted by Pittard & Goldsmith (2016). By nature, it represents an idealized scenario before more realistic simulations of filaments are conducted.…”

mentioning

confidence: 74%

“…Pittard & Goldsmith (2016) compared all three time-scales and found that the one defined by Xu & Stone (1995) for prolate clouds gave a slightly better reduction in variance between the simulations. Therefore, this time-scale, t cs , has been adopted for this paper, with the assumption that the smooth edges to the filament can be approximated as reasonably sharp edges (Pittard et al 2009).…”

Section: Initial Conditionsmentioning

confidence: 99%

“…One of the few 3D MHD resolution tests in the literature was performed by Shin et al (2008) for a spherical cloud using a non-AMR code at resolutions of R 120 and R 60 and concluded that most aspects of the MHD shock-cloud interaction were well converged at both resolutions. To our knowledge, the only resolution tests for a 3D purely hydrodynamic shock-filament interaction were performed by Pittard & Goldsmith (2016), who demonstrated that convergence was possible at a resolution of R 32 .…”

Section: Convergence Studiesmentioning

confidence: 99%

“…The most recent study, Pittard & Goldsmith (2016), investigated shock-filament interactions and studied the formation of turbulent vortices behind the filaments as a result of the shock-filament interaction. They found that varying the filament length and angle of orientation to the shock front significantly changed the nature of the interaction.…”

mentioning

confidence: 99%

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The interaction of a magnetohydrodynamical shock with a filament

Goldsmith

Pittard

2016

Mon. Not. R. Astron. Soc.

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We present 3D magnetohydrodynamic numerical simulations of the adiabatic interaction of a shock with a dense, filamentary cloud. We investigate the effects of various filament lengths and orientations on the interaction using different orientations of the magnetic field, and vary the Mach number of the shock, the density contrast of the filament χ , and the plasma beta, in order to determine their effect on the evolution and lifetime of the filament. We find that in a parallel magnetic field filaments have longer lifetimes if they are orientated more 'broadside' to the shock front, and that an increase in χ hastens the destruction of the cloud, in terms of the modified cloud-crushing time-scale, t cs . The combination of a mild shock and a perpendicular or oblique field provides the best condition for extending the life of the filament, with some filaments able to survive almost indefinitely since they are cocooned by the magnetic field. A high value for χ does not initiate large turbulent instabilities in either the perpendicular or oblique field cases but rather draws the filament out into long tendrils which may eventually fragment. In addition, flux ropes are only formed in parallel magnetic fields. The length of the filament is, however, not as important for the evolution and destruction of a filament.

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Section: Convergence Studiessupporting

confidence: 92%

mentioning

confidence: 74%

Section: Initial Conditionsmentioning

confidence: 99%

Section: Convergence Studiesmentioning

confidence: 99%

mentioning

confidence: 99%

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The interaction of a magnetohydrodynamical shock with a filament

Goldsmith

Pittard

2016

Mon. Not. R. Astron. Soc.

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Interactions of a shock with a molecular cloud at various stages of its evolution due to thermal instability and gravity

Kupilas

Wareing

Pittard

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Using the adaptive mesh refinement code mg, we perform hydrodynamic simulations of the interaction of a shock with a molecular cloud evolving due to thermal instability (TI) and gravity. To explore the relative importance of these processes, three case studies are presented. The first follows the formation of a molecular cloud out of an initially quiescent atomic medium due to the effects of TI and gravity. The second case introduces a shock whilst the cloud is still in the warm atomic phase, and the third scenario introduces a shock once the molecular cloud has formed. The shocks accelerate the global collapse of the clouds with both experiencing local gravitational collapse prior to this. When the cloud is still atomic, the evolution is shock dominated and structures form due to dynamical instabilities within a radiatively cooled shell. While the transmitted shock can potentially trigger the TI, this is prevented as material is shocked multiple times on the order of a cloud-crushing time-scale. When the cloud is molecular, the post-shock flow is directed via the pre-existing structure through low-density regions in the inter-clump medium. The clumps are accelerated and deformed as the flow induces clump–clump collisions and mergers that collapse under gravity. For a limited period, both shocked cases show a mixture of Kolmogorov and Burgers turbulence-like velocity and logarithmic density power spectra, and strongly varying density spectra. The clouds presented in this work provide realistic conditions that will be used in future feedback studies.

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Shock–multicloud interactions in galactic outflows – II. Radiative fractal clouds and cold gas thermodynamics

Banda-Barragán

Brüggen

Heesen

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Galactic winds are crucial to the cosmic cycle of matter, transporting material out of the dense regions of galaxies. Observations show the coexistence of different temperature phases in such winds, which is not easy to explain. We present a set of 3D shock-multicloud simulations that account for radiative heating and cooling at temperatures between $10^2\, \rm K$ and $10^7\, \rm K$. The interplay between shock heating, dynamical instabilities, turbulence, and radiative heating and cooling creates a complex multi-phase flow with a rain-like morphology. Cloud gas fragments and is continuously eroded, becoming efficiently mixed and mass loaded. The resulting warm mixed gas then cools down and precipitates into new dense cloudlets, which repeat the process. Thus, radiative cooling is able to sustain fast-moving dense gas by aiding condensation of gas from warm clouds and the hot wind. In the ensuing outflow, hot gas with temperatures $\gtrsim 10^6\, \rm K$ outruns the warm and cold phases, which reach thermal equilibrium near $\approx 10^4\, \rm K$ and $\approx 10^2\, \rm K$, respectively. Although the volume filling factor of hot gas is higher in the outflow, most of the mass is concentrated in dense gas cloudlets and filaments with these temperatures. More porous multicloud layers result in more vertically extended outflows, and dense gas is more efficiently produced in more compact layers. The cold phase is not accelerated by ram-pressure, but, instead, precipitates from warm and mixed gas out of thermal equilibrium. This cycle can explain the presence of high-velocity H i gas with $N_{\rm H\, {\scriptstyle I}}=10^{19-21}\, \rm cm^{-2}$ and $\Delta v_{{\rm FWHM}}\lesssim 37\, \rm km\, s^{-1}$ in the Galactic centre outflow.

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Numerical simulations of a shock-filament interaction

Cited by 10 publications

References 96 publications

The interaction of a magnetohydrodynamical shock with a filament

The interaction of a magnetohydrodynamical shock with a filament

Interactions of a shock with a molecular cloud at various stages of its evolution due to thermal instability and gravity

Shock–multicloud interactions in galactic outflows – II. Radiative fractal clouds and cold gas thermodynamics

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