Toward First-Principle Simulations of Galaxy Formation: I. How Should We Choose Star-Formation Criteria in High-Resolution Simulations of Disk Galaxies?

By Takayuki R.Saitoh, Hiroshi Daisaka, Eiichiro Kokubo, J. Makino, T. Okamoto, Kohji Tomisaka, K. Wada, Naoki Yoshida. 2008

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We performed three-dimensional N -body/SPH simulations to study how mass resolution and other model param- eters, such as the star-formation efficiency parameter, Cand the threshold density for star formation, nth affect structures of the galactic gaseous/stellar disk. We employed 10 6 -10 7 particles to resolve a cold ( T 100 cm � 3 ) phase as well as diffuse, hot phases. We found that structures of the interstellar medium (ISM) and the distribution of young stars were sensitive to the assumed values of nth. High-nth models with nth = 100 cm � 3 yielded clumpy multi-phase features in the ISM. Young stars were distributed in a thin disk, of which the half-mass scale height was 10-30 pc. In low-nth models with nth = 0.1 cm � 3 , which is usually employed in cosmological galaxy-formation simulations, the gas disk appears to be smoother and the stellar disk is found to be several-times thicker than the high-nth models. A high-resolution simulation with high-nth is necessary to reproduce the complex structure of the gas disk. The global star-formation properties of galaxies, such as the star-formation history, in low-nth models are similar to those in high-nth models when we tune the value of Cso that they repro- duce the observed relation between the surface gas density and the surface star-formation rate density. We however emphasize that high-nth models automatically reproduce the relation, regardless of the values of C� .T he ISM structure, phase distribution and distributions of young star-forming regions are quite similar in runs with different values of C� . We found that the timescale of the flow from the reservoir (nH � 1c m � 3 ) to the star-forming regions (nH & 100cm � 3 ) is about five-times as long as the local dynamical time, and this evolution timescale is independent

Subfields: Astronomy and Astrophysics

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Citations in the corpus

The meaning and consequences of star formation criteria in galaxy models with resolved stellar feedback (2013, background): “Without a sufficiently strict minimum SF criterion, the ability of the gas to form realistic phase structure (Saitoh et al. 2008), or blow winds that regulate its baryon content (Governato et al. 2010) and form realistic disks (Pontzen & Governato 2012; Governato et al. 2004) can be fundamentally…”
Dark matter cores all the way down (2015, background): “This illustrates that order of magnitude changes in simulation parameters have no significant effect on our conclusions (see also e.g. Saitoh et al. 2008; Hopkins et al. 2011).”
Star formation in galaxy mergers with realistic models of stellar feedback and the interstellar medium (2012, background): “Numerical simulations of isolated galaxies and galaxy mergers can now achieve the dynamic range required to resolve the formation of GMC and ISM structure, ∼1–10 pc (see e.g. Saitoh et al. 2008; Tasker & Tan 2009; Bournaud et al. 2010; Dobbs, Burkert & Pringle 2011).”
Understanding the shape and diversity of dwarf galaxy rotation curves in ΛCDM (2016, background): “…capture the momentum injection into the interstellar medium (ISM) generated by expanding bubbles of shock heated gas (e.g. Kimm et al. 2015); and (ii) star formation becomes self-regulated by stellar feedback (e.g. Kravtsov 2003; Saitoh et al. 2008; Hopkins et al. 2011, 2013; Agertz et al. 2013).”
BARYONS MATTER: WHY LUMINOUS SATELLITE GALAXIES HAVE REDUCED CENTRAL MASSES (2012, background): “…scenarios is the ability to resolve the high density clumps where star formation takes place, i.e., overdensities comparable to giant molecular clouds (Robertson & Kravtsov 2008; Saitoh et al. 2008; Tasker & Bryan 2008; Ceverino & Klypin 2009; Christensen et al. 2010; Coĺın et al. 2010).”
Hierarchical formation of bulgeless galaxies: why outflows have low angular momentum (2010, background): “Star formation occurs when cold gas reaches a given threshold density (Stinson et al. 2006), which is dependent on the volume of the star forming regions that can be resolved (Saitoh et al. 2008; Robertson & Kravtsov 2008; Tasker & Bryan 2008).”
Cuspy No More: How Outflows Affect the Central Dark Matter and Baryon Distribution in Lambda CDM Galaxies (2012, methodology): “The necessity of simulations to resolve dense gas regions calls for simulations of very high mass and spatial resolution (Mashchenko et al. 2008; Saitoh et al. 2008; Ceverino & Klypin 2009).”
FIRE-2 simulations: physics versus numerics in galaxy formation (2017, methodology): “…and simulations using very different feedback mechanisms (removing SNe, stellar mass-loss, or HII photo-heating); and in different codes (see e.g. Saitoh et al. 2008; Shetty & Ostriker 2008; Hopkins et al. 2012b, 2013c, 2011, 2013a,d,e, 2016; Federrath & Klessen 2012; Agertz et al. 2013; Kim…”
The properties of satellite galaxies in simulations of galaxy formation (2009, unknown): “In order to prevent this from happening, several authors have adopted a similar strategy to us by imposing a minimum pressure for high-density gas (Robertson & Kravtsov 2008; Saitoh et al. 2008; Ceverino et al. 2009; Crain et al. 2009; Schaye et al. 2010).”
ENVIRONMENTAL DEPENDENCE OF THE KENNICUTT–SCHMIDT RELATION IN GALAXIES (2010, background): “For the same reason, the global rate of star formation may be controlled by the rate with which dense gas is formed by the ISM, rather then by the assumed local efficiency of the gas (Saitoh et al. 2008).”
How supernova feedback turns dark matter cusps into cores (2011, unknown): “Saitoh et al. 2008).”
Self-regulated star formation in galaxies via momentum input from massive stars (2011, background): “…by C alifornia Institute of Technology user on 21 M ay 2020 can now reach the resolution required to resolve the formation of GMCs, ∼1–100 pc (see e.g. Saitoh et al. 2008; Tasker & Tan 2009; Bournaud et al. 2010; Dobbs, Burkert & Pringle 2011) (note that GMCs in massive gas-rich galaxies are ∼…”
The Dynamical and Chemical Evolution of Dwarf Spheroidal Galaxies with GEAR (2009, methodology): “Saitoh et al. (2008) concluded that only models using a high threshold density (ρsfr = 100 mH/cm3) are able to reproduce the complex, inhomogeneous, and multiphase structure of the ISM.”