Feedback-regulated star formation in molecular clouds and galactic discs

By C. Faucher-Giguére, E. Quataert, P. Hopkins. 2013

159 citations recorded by the source corpus.

We present a two-zone theory for feedback-regulated star formation in galactic discs, consistently connecting the galaxy-averaged star formation law with star formation proceeding in giant molecular clouds (GMCs). Our focus is on galaxies with gas surface density Sigma_g>~100 Msun pc^-2. In our theory, the galactic disc consists of Toomre-mass GMCs embedded in a volume-filling ISM. Radiation pressure on dust disperses GMCs and most supernovae explode in the volume-filling medium. A galaxy-averaged star formation law is derived by balancing the momentum input from supernova feedback with the gravitational weight of the disc gas. This star formation law is in good agreement with observations for a CO conversion factor depending continuously on Sigma_g. We argue that the galaxy-averaged star formation efficiency per free fall time, epsilon_ff^gal, is only a weak function of the efficiency with which GMCs convert their gas into stars. This is possible because the rate limiting step for star formation is the rate at which GMCs form: for large efficiency of star formation in GMCs, the Toomre Q parameter obtains a value slightly above unity so that the GMC formation rate is consistent with the galaxy-averaged star formation law. We contrast our results with other theories of turbulence-regulated star formation and discuss predictions of our model. Using a compilation of data from the literature, we show that the galaxy-averaged star formation efficiency per free fall time is non-universal and increases with increasing gas fraction, as predicted by our model. We also predict that the fraction of the disc gas mass in bound GMCs decreases for increasing values of the GMC star formation efficiency. This is qualitatively consistent with the smooth molecular gas distribution inferred in local ultra-luminous infrared galaxies and the small mass fraction in giant clumps in high-redshift galaxies.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/283b1f6fbb3ddeaed533aac0117b3c77ad0ade29

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Citations in the corpus

RECONCILING THE STELLAR AND NEBULAR SPECTRA OF HIGH-REDSHIFT GALAXIES (2016, background): “…and supernova explosions are the principal sources of feedback that ultimately control the galaxy formation process (e.g., Murray et al. 2005; Faucher-Giguère et al. 2013; Hopkins et al. 2014; Muratov et al. 2015), and they dominate the bolometric luminosity of rapidly forming galaxies,…”
Dusty Star Forming Galaxies at High Redshift (2014, background): “On the other hand, in starburst-dominated regimes, where supernova-driven turbulence dominates the velocity dispersion and gas dominates the vertical pressure, Ostriker and Shetty (2011) and Faucher-Giguère et al. (2013) find an index of ∼2 should describe the KS relation.”
FIRE-2 simulations: physics versus numerics in galaxy formation (2017, background): “Recently, similar implementations to ours have also found consistent results on large scales (Semenov et al. 2016; Agertz & Kravtsov 2016), consistent with analytic expectations (Ostriker & Shetty 2011; Faucher-Giguère et al. 2013).”
The origin and evolution of the galaxy mass–metallicity relation (2015, background): “…is physically required to obtain the correct spatial star formation distribution in galaxies (Hopkins et al. 2013b; Padoan & Nordlund 2011), but the galaxy-averaged star formation efficiency is regulated by feedback at much lower values (∼ 1% per dynamical time, e.g. Faucher-Giguère et al. 2013).”
The cosmic baryon cycle and galaxy mass assembly in the FIRE simulations (2016, background): “…formation efficiency on larger scales is regulated by the rate of formation and disruption of giant molecular clouds by feedback processes (e.g. Faucher-Giguère et al. 2013), and it is fairly insensitive to the density threshold and other details of the small scale star formation law (Hopkins…”
A Redshift-independent Efficiency Model: Star Formation and Stellar Masses in Dark Matter Halos at z ≳ 4 (2018, background): “The SFR is determined by the production and disruption of dense, star-forming gas, which depends on gravity, gas compression, and regulating nature of feedback (Thompson et al. 2005; Ostriker & Shetty 2011; Faucher-Giguère et al. 2013).”
A unified model for galactic discs: star formation, turbulence driving, and mass transport (2017, methodology): “This equation is identical up to factors of order unity with equation 18 of Faucher-Giguère et al. (2013).”
How Stellar Feedback Simultaneously Regulates Star Formation and Drives Outflows (2015, methodology): “Various previous works have presented such models (e.g.Murray et al. 2005, 2011; Thompson et al. 2005; Ostriker et al. 2010; Ostriker & Shetty 2011; Shetty & Ostriker 2012; Faucher-Giguère et al. 2013).”
Galaxies on FIRE (Feedback In Realistic Environments): stellar feedback explains cosmologically inefficient star formation (2013, result): “We also note that, as many previous studies have pointed out (Murray et al. 2005; McKee & Ostriker 2007; Shetty & Ostriker 2008; Faucher-Giguère et al. 2013), it is ultimately the momentum injected by SNe, not just the thermal energy, which regulates star formation.”
Physical Models of Galaxy Formation in a Cosmological Framework (2014, methodology): “Models with significant ISM pressurization, either imposed (Genel et al. 2012) or selfconsistently generated (Faucher-Giguère et al. 2013), matched stellar fraction constraints and still produced massive clumps, but these were less prominent and quicker to disrupt.”
Physical Processes in the Interstellar Medium (2014, background): “However, this does not mean that gravitational instability is unimportant in these systems, as simulations show that star formation in disk galaxies tends to self-regulate so that Q∼ 1 (e.g. Krumholz & Burkert, 2010; Faucher-Giguère et al., 2013).”
Supernova feedback in an inhomogeneous interstellar medium (2014, methodology): “Faucher-Giguère et al. (2013) noted that this scaling is inconsistent with the weaker scaling Pfin ∝ n−1/7H indicated by other analytic models and numerical simulations of SNR evolution (e.g. Cioffi et al. 1988; Draine & Woods 1991; Blondin et al. 1998).”
Neutral hydrogen in galaxy haloes at the peak of the cosmic star formation history (2014, methodology): “Numerical simulations (Hopkins et al. 2011; Agertz et al. 2013) and analytic models (e.g., Faucher-Giguère et al. 2013) that are successful at reproducing the observed Kennicutt-Schmidt law (Kennicutt 1998; Genzel et al. 2010) indicate that the formation of GMCs is the rate-limiting step for star…”
The difficulty of getting high escape fractions of ionizing photons from high-redshift galaxies: A view from the FIRE cosmological simulations (2015, background): “This is because the galaxyaveraged star formation efficiency is regulated by stellar feedback (1–2% per dynamical time, e.g. Hopkins et al. 2011; Ostriker & Shetty 2011; Agertz et al. 2013; Faucher-Giguère et al. 2013), not the SF criteria (Hopkins et al. 2013).”