Towards the complete census of molecular hydrogen in a simulated disc galaxy

Nickerson, Sarah; Teyssier, Romain; Rosdahl, Joakim

doi:10.1093/mnras/stz048

Cited by 18 publications

(13 citation statements)

References 131 publications

(247 reference statements)

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“…22). Other numerical studies of GMCs in a galactic environment come to similar conclusions (see, for instance, Nickerson, Teyssier & Rosdahl 2019, in particular their fig. 14).…”

Section: Scaling Relationssupporting

confidence: 64%

Simulations of the star-forming molecular gas in an interacting M51-like galaxy: cloud population statistics

Treß

Sormani

Smith

et al. 2021

Monthly Notices of the Royal Astronomical Society

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To investigate how molecular clouds react to different environmental conditions at a galactic scale, we present a catalogue of giant molecular clouds resolved down to masses of ∼10 M⊙ from a simulation of the entire disc of an interacting M51-like galaxy and a comparable isolated galaxy. Our model includes time-dependent gas chemistry, sink particles for star formation and supernova feedback, meaning we are not reliant on star formation recipes based on threshold densities and can follow the physics of the cold molecular phase. We extract giant molecular clouds from the simulations and analyse their properties. In the disc of our simulated galaxies, spiral arms seem to act merely as snowplows, gathering gas and clouds without dramatically affecting their properties. In the centre of the galaxy, on the other hand, environmental conditions lead to larger, more massive clouds. While the galaxy interaction has little effect on cloud masses and sizes, it does promote the formation of counter-rotating clouds. We find that the identified clouds seem to be largely gravitationally unbound at first glance, but a closer analysis of the hierarchical structure of the molecular interstellar medium shows that there is a large range of virial parameters with a smooth transition from unbound to mostly bound for the densest structures. The common observation that clouds appear to be virialised entities may therefore be due to CO bright emission highlighting a specific level in this hierarchical binding sequence. The small fraction of gravitationally bound structures found suggests that low galactic star formation efficiencies may be set by the process of cloud formation and initial collapse.

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“…22). Other numerical studies of GMCs in a galactic environment come to similar conclusions (see, for instance, Nickerson, Teyssier & Rosdahl 2019, in particular their fig. 14).…”

Section: Scaling Relationssupporting

confidence: 64%

Simulations of the star-forming molecular gas in an interacting M51-like galaxy: cloud population statistics

Treß

Sormani

Smith

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…Such recipes have been used in computations in which star formation is assumed to require the presence of H 2 (Fu et al 2010;Christensen et al 2012;Kuhlen et al 2012;Popping et al 2014Popping et al , 2015Thompson et al 2014;Davé et al 2016;Xie et al 2017), or simply for partitioning the cold gas between Hi and H 2 (Obreschkow et al 2009;Lagos et al 2011Lagos et al , 2015Bekki 2013;Marinacci et al 2017;Diemer et al 2018). Simulations have also been carried out in which the (nonequilibrium) H 2formation/destruction chemistry is computed on the fly using subgrid prescriptions for the photodissociating radiation fields and cold gas densities (Robertson & Kravtsov 2008;Tomassetti et al 2015;Hu et al 2016;Lupi et al 2018;Nickerson et al 2018Nickerson et al , 2019.…”

Section: What Drives the Ratio Of H 2 To Hi?mentioning

confidence: 99%

The Evolution of the Star-Forming Interstellar Medium Across Cosmic Time

Tacconi

Genzel

Sternberg

2020

Annu. Rev. Astron. Astrophys.

362

327

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Over the past decade, increasingly robust estimates of the dense molecular gas content in galaxy populations between redshift z = 0 and the peak of cosmic galaxy/star formation ( z ∼ 1–3) have become available. This rapid progress has been possible due to the advent of powerful ground- and space-based telescopes for the combined study of several millimeter to far-IR, line or continuum tracers of the molecular gas and dust components. The main conclusions of this review are as follows: ▪ Star-forming galaxies contained much more molecular gas at earlier cosmic epochs than at the present time. ▪ The galaxy-integrated depletion timescale for converting the gas into stars depends primarily on z or Hubble time and, at a given z, on the vertical location of a galaxy along the star-formation rate versus stellar mass main sequence (MS) correlation. ▪ Global rates of galaxy gas accretion primarily control the evolution of the cold molecular gas content and star-formation rates of the dominant MS galaxy population, which in turn vary with cosmological expansion. Another key driver may be global disk fragmentation in high- z, gas-rich galaxies, which ties local free-fall timescales to galactic orbital times and leads to rapid radial matter transport and bulge growth. The low star-formation efficiency inside molecular clouds is plausibly set by supersonic streaming motions and internal turbulence, which in turn may be driven by conversion of gravitational energy at high z and/or by local feedback from massive stars at low z. ▪ A simple gas regulator model is remarkably successful in predicting the combined evolution of molecular gas fractions, star-formation rates, galactic winds, and gas-phase metallicities. Expected final online publication date for the Annual Review of Astronomy, Volume 58 is August 18, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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“…We decompose the baryonic content of galaxies by measuring the amount of stars and gas within twice the effective radius of galaxies; these values are also obtained within R eff or 0.1R vir and show similar behaviour. The gas content is further decomposed into a cold and dense gas component (identified by a subscript 'cd' in gas quantities) by considering only the star formation gas with density n ≥ 0.1, 10 cm −3 and temperature T < 2 × 10 4 K. In the following, we distinguish between the neutral HI+H 2 gas component with the density cut-off at 0.1 cm −3 , and the H 2 molecular dense component at 10 cm −3 (e.g., Lupi et al 2018;Nickerson et al 2019). An exact match of the ionisation and molecular states of the gas however would require a detailed treatment of radiative transfer and molecular chemistry.…”

Section: Baryonic Contentmentioning

confidence: 99%

Introducing the NEWHORIZON simulation: Galaxy properties with resolved internal dynamics across cosmic time

Dubois

Beckmann

Bournaud

et al. 2021

A&A

151

100

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Hydrodynamical cosmological simulations are increasing their level of realism by considering more physical processes and having greater resolution or larger statistics. However, usually either the statistical power of such simulations or the resolution reached within galaxies are sacrificed. Here, we introduce the NEWHORIZON project in which we simulate at high resolution a zoom-in region of ∼(16 Mpc)3 that is larger than a standard zoom-in region around a single halo and is embedded in a larger box. A resolution of up to 34 pc, which is typical of individual zoom-in, up-to-date resimulated halos, is reached within galaxies; this allows the simulation to capture the multi-phase nature of the interstellar medium and the clumpy nature of the star formation process in galaxies. In this introductory paper, we present several key fundamental properties of galaxies and their black holes, including the galaxy mass function, cosmic star formation rate, galactic metallicities, the Kennicutt–Schmidt relation, the stellar-to-halo mass relation, galaxy sizes, stellar kinematics and morphology, gas content within galaxies and its kinematics, and the black hole mass and spin properties over time. The various scaling relations are broadly reproduced by NEWHORIZON with some differences with the standard observables. Owing to its exquisite spatial resolution, NEWHORIZON captures the inefficient process of star formation in galaxies, which evolve over time from being more turbulent, gas rich, and star bursting at high redshift. These high-redshift galaxies are also more compact, and they are more elliptical and clumpier until the level of internal gas turbulence decays enough to allow for the formation of discs. The NEWHORIZON simulation gives access to a broad range of galaxy formation and evolution physics at low-to-intermediate stellar masses, which is a regime that will become accessible in the near future through surveys such as the LSST.

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Towards the complete census of molecular hydrogen in a simulated disc galaxy

Cited by 18 publications

References 131 publications

Simulations of the star-forming molecular gas in an interacting M51-like galaxy: cloud population statistics

Simulations of the star-forming molecular gas in an interacting M51-like galaxy: cloud population statistics

The Evolution of the Star-Forming Interstellar Medium Across Cosmic Time

Introducing the NEWHORIZON simulation: Galaxy properties with resolved internal dynamics across cosmic time

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