IMPLEMENTATION OF SINK PARTICLES IN THE
                    <i>ATHENA</i>
                    CODE

Gong, Hao; Ostriker, Eve C.

doi:10.1088/0067-0049/204/1/8

Cited by 64 publications

(67 citation statements)

References 37 publications

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“…Furthermore, sink particles cannot be created inside an exclusion radius of r excl = 12 ∆x around already created sink particles. These conditions for sink particle creation are similar to those implemented in previous works (Padoan et al 2012Bate et al 1995;Krumholz et al 2004;Federrath et al 2010;Gong & Ostriker 2013). A sink particle is first created without any mass, but is immediately allowed to accrete.…”

Section: Numerical Parameters and The Sink Particle Modelmentioning

confidence: 80%

Large-scale numerical simulations of star formation put to the test

Frimann

Jørgensen

Haugbølle

2016

A&A

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Context. Both observations and simulations of embedded protostars have progressed rapidly in recent years. Bringing them together is an important step in advancing our knowledge about the earliest phases of star formation. Aims. To compare synthetic continuum images and spectral energy distributions (SEDs), calculated from large-scale numerical simulations, to observational studies, thereby aiding in both the interpretation of the observations and in testing the fidelity of the simulations. Methods.The adaptive mesh refinement code, RAMSES, is used to simulate the evolution of a 5 pc × 5 pc × 5 pc molecular cloud. The simulation has a maximum resolution of 8 AU, resolving simultaneously the molecular cloud on parsec scales and individual protostellar systems on AU scales. The simulation is post-processed with the radiative transfer code RADMC-3D, which is used to create synthetic continuum images and SEDs of the protostellar systems. In this way, more than 13 000 unique radiative transfer models, of a variety of different protostellar systems, are produced. Results. Over the course of 0.76 Myr the simulation forms more than 500 protostars, primarily within two sub-clusters. The synthetic SEDs are used to calculate evolutionary tracers T bol and L smm /L bol . It is shown that, while the observed distributions of the tracers are well matched by the simulation, they generally do a poor job of tracking the protostellar ages. Disks form early in the simulation, with 40% of the Class 0 protostars being encircled by one. The flux emission from the simulated disks is found to be, on average, a factor ∼6 too low relative to real observations; an issue that can be traced back to numerical effects on the smallest scales in the simulation. The simulated distribution of protostellar luminosities spans more than three order of magnitudes, similar to the observed distribution. Cores and protostars are found to be closely associated with one another, with the distance distribution between them being in excellent agreement with observations. Conclusions. The analysis and statistical comparison of synthetic observations to real ones is established as a powerful tool in the interpretation of observational results. By using a large set of post-processed protostars, which make statistical comparisons to observational surveys possible, this approach goes beyond comparing single objects to isolated models of star-forming cores.

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Section: Numerical Parameters and The Sink Particle Modelmentioning

confidence: 80%

Large-scale numerical simulations of star formation put to the test

Frimann

Jørgensen

Haugbølle

2016

A&A

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“…Stars are represented within the code by point-mass sink particles (Gong & Ostriker 2013). Sink particles are formed dynamically when cells exceed a density threshold ρ th = 8.86 c 2 s /(πG∆x 2 ) motivated by the Larson (1969) and Penston (1969) solutions for self-gravitating isothermal collapse.…”

Section: Equations and Algorithmsmentioning

confidence: 99%

Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. I. Star Formation Rate and Efficiency

Raskutti

Ostriker

Skinner

2016

ApJ

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111

131

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Radiation feedback from stellar clusters is expected to play a key role in setting the rate and efficiency of star formation in giant molecular clouds (GMCs). To investigate how radiation forces influence realistic turbulent systems, we have conducted a series of numerical simulations employing the Hyperion radiation hydrodynamics solver, considering the regime that is optically thick to ultraviolet (UV) and optically thin to infrared (IR) radiation. Our model clouds cover initial surface densities between Σ cl,0 ∼ 10 − 300 M pc −2 , with varying initial turbulence. We follow them through turbulent, self-gravitating collapse, formation of star clusters, and cloud dispersal by stellar radiation. All our models display a lognormal distribution of gas surface density Σ; for an initial virial parameter α vir,0 = 2, the lognormal standard deviation is σ lnΣ = 1 − 1.5 and the star formation rate coefficient ε ff,ρ = 0.3 − 0.5, both of which are sensitive to turbulence but not radiation feedback. The net star formation efficiency ε final increases with Σ cl,0 and decreases with α vir,0 . We interpret these results via a simple conceptual framework, whereby steady star formation increases the radiation force, such that local gas patches at successively higher Σ become unbound. Based on this formalism (with fixed σ lnΣ ), we provide an analytic upper bound on ε final , which is in good agreement with our numerical results. The final star formation efficiency depends on the distribution of Eddington ratios in the cloud and is strongly increased by turbulent compression of gas.

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“…Various works have invoked sink particles in order to advance their goals (e.g., Bate et al 1995;Krumholz et al 2004;Federrath et al 2010;Wang et al 2010;Teyssier et al 2011;Gong & Ostriker 2013). We implement the sink particle method largely based on Wang et al (2010), who studied massive star formation using Enzo AMR simulations.…”

Section: Sink Particle Algorithmmentioning

confidence: 99%

“…The second option involves the sink particle method, successfully applied to star formation and other problems to focus on a specific range in radius, preventing the smaller scales from forcing an increasingly small timestep, and thus enabling one to follow the long-term evolution of the collapsing flow (e.g., Bate et al 1995;Krumholz et al 2004;Federrath et al 2010;Wang et al 2010;Teyssier et al 2011;Gong & Ostriker 2013). In this method, gas on small spatial scales is replaced by the sink particles, which can grow in mass as the surrounding gas evolves.…”

Section: Introductionmentioning

confidence: 99%

Supermassive black hole seed formation at high redshifts: long-term evolution of the direct collapse

Shlosman

Choi

Begelman

et al. 2015

Mon. Not. R. Astron. Soc.

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We use cosmological adaptive mesh refinement (AMR) code Enzo zoom-in simulations to study the long term evolution of the collapsing gas within dark matter halos at z. This direct collapse process is a leading candidate for rapid formation of supermassive black hole (SMBH) seeds. To circumvent the Courant condition at small radii, we apply the sink particle method, focusing on evolution on scales ∼ 0.01 − 10 pc. The collapse proceeds in two stages, with the secondary runaway happening within the central 10 pc. The sink particles form when the collapsing gas requires additional refinement of the grid size at the highest refinement level. Their growth is negligible with the sole exception of the central seed which grows dramatically to M seed ∼ 2 × 10 6 M ⊙ in ∼ 2 Myr, confirming the feasibility of this path to the SMBH. The variability of angular momentum in the accreted gas results in the formation of two misaligned disks. Both disks lie within the Roche limit of the central seed. While the inner disk is geometrically thin and weakly asymmetric, the outer disk flares due to turbulent motions as a result of the massive inflow along a pair of penetrating filaments. The filamentary inflow determines the dominant Fourier modes in this disk -these modes have a non-self-gravitational origin. We do not confirm that m = 1 is a dominant mode that drives the inflow in the presence of a central massive object. The overall configuration appears to be generic, and is expected to form when the central seed becomes sufficiently massive.

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IMPLEMENTATION OF SINK PARTICLES IN THE ATHENA CODE

Cited by 64 publications

References 37 publications

Large-scale numerical simulations of star formation put to the test

Large-scale numerical simulations of star formation put to the test

Numerical Simulations of Turbulent Molecular Clouds Regulated by Radiation Feedback Forces. I. Star Formation Rate and Efficiency

Supermassive black hole seed formation at high redshifts: long-term evolution of the direct collapse

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