The SILCC (SImulating the LifeCycle of molecular Clouds) project – I. Chemical evolution of the supernova-driven ISM

By Stefanie Walch, P. Girichidis, T. Naab, A. Gatto, S. Glover, R. Wunsch, Ralf Klessen, P. C. Clark, Thomas Peters, Dominik Derigs and 1 more. 2014

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The SILCC (SImulating the Life-Cycle of molecular Clouds) project aims to self-consistently understand the small-scale structure of the interstellar medium (ISM) and its link to galaxy evolution. We simulate the evolution of the multiphase ISM in a (500 pc)2 × ±5 kpc region of a galactic disc, with a gas surface density of ΣGAS=10M⊙pc−2. The flash 4 simulations include an external potential, self-gravity, magnetic fields, heating and radiative cooling, time-dependent chemistry of H2 and CO considering (self-) shielding, and supernova (SN) feedback but omit shear due to galactic rotation. We explore SN explosions at different rates in high-density regions (peak), in random locations with a Gaussian distribution in the vertical direction (random), in a combination of both (mixed), or clustered in space and time (clus/clus2). Only models with self-gravity and a significant fraction of SNe that explode in low-density gas are in agreement with observations. Without self-gravity and in models with peak driving the formation of H2 is strongly suppressed. For decreasing SN rates, the H2 mass fraction increases significantly from <10 per cent for high SN rates, i.e. 0.5 dex above Kennicutt–Schmidt, to 70–85 per cent for low SN rates, i.e. 0.5 dex below KS. For an intermediate SN rate, clustered driving results in slightly more H2 than random driving due to the more coherent compression of the gas in larger bubbles. Magnetic fields have little impact on the final disc structure but affect the dense gas (n ≳ 10 cm−3) and delay H2 formation. Most of the volume is filled with hot gas (∼80 per cent within ±150 pc). For all but peak driving a vertically expanding warm component of atomic hydrogen indicates a fountain flow. We highlight that individual chemical species populate different ISM phases and cannot be accurately modelled with temperature-/density-based phase cut-offs.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5552a9a34c63503794c25f4389441ea16aab30f2

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Citations in the corpus

The SILCC (SImulating the LifeCycle of molecular Clouds) project - II. Dynamical evolution of the supernova-driven ISM and the launching of outflows (2015, methodology): “Within the SILCC project (SImulating the Life-Cycle of molecular Clouds1), starting with Walch et al. (2015), we aim to advance our understanding of the physical processes in the ISM by investigating the impact of differently placed SNe as individual explosions as well as clustered explosions.”
Molecular hydrogen abundances of galaxies in the EAGLE simulations (2015, methodology): “…of the ISM and in individual galaxy simulations in which H2 formation has been implemented (e.g. Pelupessy, Papadopoulos & van der Werf 2006; Robertson & Kravtsov 2008; Gnedin, Tassis & Kravtsov 2009; Pelupessy & Papadopoulos 2009; Christensen et al. 2012; Glover & Clark 2012; Walch et al. 2015).”
Theoretical Challenges in Galaxy Formation (2016, methodology): “By creating the hot, X-ray emitting, phase they impact the large-scale multi-phase structure of the ISM (Li et al. 2015, McKee & Ostriker 1977, Walch et al. 2015) and might be important for driving galactic outflows, fountain flows, and galactic winds through hot, low density, chimneys (Chevalier &…”
The SILCC project - III. Regulation of star formation and outflows by stellar winds and supernovae (2016, background): “…can create a hot ionized medium (Cox & Smith 1974; McKee & Ostriker 1977) with high volume-filling factors (Ferrière 2001; Kalberla & Dedes 2008; Walch et al. 2015), which may launch powerful outflows from galactic discs (e.g. Oppenheimer et al. 2010; Creasey, Theuns & Bower 2013; Hopkins et…”
Three-phase Interstellar Medium in Galaxies Resolving Evolution with Star Formation and Supernova Feedback (TIGRESS): Algorithms, Fiducial Model, and Convergence (2016, background): “…in driving turbulence and shaping the multiphase ISM in galactic disks have been extensively investigated (e.g., Korpi et al. 1999; de Avillez 2000; de Avillez & Breitschwerdt 2004; Joung & Mac Low 2006; Hill et al. 2012; Gent et al. 2013; Walch et al. 2015; Girichidis et al. 2016; Li et al. 2017).”