MODELING COLLAPSE AND ACCRETION IN TURBULENT GAS CLOUDS: IMPLEMENTATION AND COMPARISON OF SINK PARTICLES IN AMR AND SPH

By Christoph Federrath, Robi Banerjee, P. C. Clark, Ralf Klessen. 2010

304 citations recorded by the source corpus.

Star formation is such a complex process that accurate numerical tools are needed to quantitatively examine the mass distribution and accretion of fragments in collapsing, turbulent, magnetized gas clouds. To enable a numerical treatment of this regime, we implemented sink particles in the adaptive mesh refinement (AMR) hydrodynamics code FLASH. Sink particles are created in regions of local gravitational collapse, and their trajectories and accretion can be followed over many dynamical times. We perform a series of tests including the time integration of circular and elliptical orbits, the collapse of a Bonnor–Ebert sphere, and a rotating, fragmenting cloud core. We compare the collapse of a highly unstable singular isothermal sphere to the theory by Shu and show that the sink particle accretion rate is in excellent agreement with the theoretical prediction. To model eccentric orbits and close encounters of sink particles accurately, we show that a very small time step is often required, for which we implemented subcycling of the N-body system. We emphasize that a sole density threshold for sink particle creation is insufficient in supersonic flows, if the density threshold is below the opacity limit. In that case, the density can exceed the threshold in strong shocks that do not necessarily lead to local collapse. Additional checks for bound state, gravitational potential minimum, Jeans instability, and converging flows are absolutely necessary for meaningful creation of sink particles. We apply our new sink particle module for FLASH to the formation of a stellar cluster, and compare to a smoothed particle hydrodynamics (SPH) code with sink particles. Our comparison shows encouraging agreement of gas properties, indicated by column density distributions and radial profiles, and of sink particle formation times and positions. We find excellent agreement in the number of sink particles formed, and in their accretion and mass distributions.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/1b97b223003ab83eb089f1cab999202e11c4c344

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Citations in the corpus

THE STAR FORMATION RATE OF TURBULENT MAGNETIZED CLOUDS: COMPARING THEORY, SIMULATIONS, AND OBSERVATIONS (2012, methodology): “…1994), intermittency introduces skewness and kurtosis in the distributions (Klessen 2000; Kritsuk et al. 2007; Burkhart et al. 2009), which becomes stronger for more compressive forcing (Schmidt et al. 2009; Federrath et al. 2010b) and for higher Mach numbers (Konstandin et al. 2012b).”
LIMITING ACCRETION ONTO MASSIVE STARS BY FRAGMENTATION-INDUCED STARVATION (2010, methodology): “…version of the hybridcharacteristics raytracing method (Rijkhorst et al. 2006; Peters et al. 2010a) to propagate the radiation on the grid and couple sink particles (Federrath et al. 2010), which we use as models of protostars, to the radiation module via a prestellar model (Peters et al. 2010a).”
Inefficient star formation through turbulence, magnetic fields and feedback (2015, methodology): “This avoids spurious formation of sink particles and guarantees that only bound and collapsing gas forms stars (Federrath et al. 2010a), which is important for accurately measuring the SFR.”
RADIATION MAGNETOHYDRODYNAMIC SIMULATIONS OF PROTOSTELLAR COLLAPSE: PROTOSTELLAR CORE FORMATION (2012, methodology): “…long-term simulations, we have to modify our code, for example, by introducing the sink particle technique (Bate et al. 1995; Krumholz et al. 2004; Federrath et al. 2010) to replace the protostellar core with a subgrid stellar evolution model (e.g., Baraffe et al. 2002; Yorke & Bodenheimer 2008;…”
THE FORMATION OF LOW-MASS BINARY STAR SYSTEMS VIA TURBULENT FRAGMENTATION (2010, methodology): “Although our sink particle method excludes formation in high-velocity gas, for the NRT run it is likely that some cold fragmentation could be reduced by additional sink criteria for the gravitational potential and gravitational boundedness of clumps (Federrath et al. 2010).”
Collapse, outflows and fragmentation of massive, turbulent and magnetized prestellar barotropic cores (2011, methodology): “This problem could partially be solved if sink particles were used (Bate & Burkert 1997, Krumholz et al. 2004, Federrath et al. 2010).”
Formation and evolution of primordial protostellar systems (2012, background): “Recent studies have circumvented this limitation by employing ‘sink particles’ that represent growing protostars (e.g. Bate, Bonnell & Price 1995; Krumholz, McKee & Klein 2004; Jappsen et al. 2005; Federrath et al. 2010).”
THE INTERPLAY OF MAGNETIC FIELDS, FRAGMENTATION, AND IONIZATION FEEDBACK IN HIGH-MASS STAR FORMATION (2010, methodology): “We use sink particles (Federrath et al. 2010) to model young stars.”
SIMULATIONS ON A MOVING MESH: THE CLUSTERED FORMATION OF POPULATION III PROTOSTARS (2011, methodology): “Both techniques have been used in (radiation) hydrodynamic simulations of star cluster formation in the presentday universe (Klessen & Burkert 2000; Bate et al. 2003; Krumholz et al. 2009; Federrath et al. 2010; Peters et al. 2010).”
Phantom: A Smoothed Particle Hydrodynamics and Magnetohydrodynamics Code for Astrophysics (2017, methodology): “The checks above are the same as those in Bate et al. (1995), with the addition of the additional check from Federrath et al. (2010b) to ensure that sink particles are only created in a local minimum of the gravitational potential.”
ON THE STAR FORMATION EFFICIENCY OF TURBULENT MAGNETIZED CLOUDS (2012, methodology): “If all these criteria are fulfilled, the excess mass above the density threshold defined by Equation (1) is removed from the MHD system and added to the sink particle, such that mass, momentum and angular momentum are conserved by construction (see Federrath et al. 2010a, 2011a, for details).”
The SILCC project - III. Regulation of star formation and outflows by stellar winds and supernovae (2016, methodology): “The according forces are computed from particle–particle as well as gas–particle interaction (for more details see Federrath et al. 2010).”
Importance of the Initial Conditions for Star Formation - I. Cloud Evolution and Morphology (2010, methodology): “Since dense cores are typically embedded in large scale, turbulent molecular clouds, an effective driving of the internal turbulence from outside the core is expected (e.g. Klessen, Heitsch & Mac Low 2000b; Federrath et al. 2010b).”
On the universality of interstellar filaments: theory meets simulations and observations (2015, methodology): “Columns 2–5: whether gravity and star formation are included, the type of turbulence driving (Federrath et al. 2010b; Federrath 2013), the magnetic field strength, and whether jet/outflow feedback is included.”
FIRE-2 simulations: physics versus numerics in galaxy formation (2017, background): “Hopkins et al. (2013d) and many other studies (Li et al. 2005; Federrath et al. 2010; Padoan & Nordlund 2011; Padoan et al. 2012) have shown c© 0000 RAS, MNRAS 000, 000–000 this is more useful than a density criterion (as well as more accurate in converging to the results of higher-resolution…”