Stellar Feedback in Galaxies and the Origin of Galaxy-scale Winds

By P. Hopkins, E. Quataert, N. Murray. 2011

427 citations recorded by the source corpus.

Feedback from massive stars is believed to play a critical role in driving galactic superwinds that enrich the intergalactic medium and shape the galaxy mass function, massmetallicity relation, and other global galaxy properties. In previous papers, we have introduced new numerical methods for implementing stellar feedback on sub-GMC through galactic scales in numerical simulations of galaxies; the key physical processes include radiation pressure in the UV through IR, supernovae (Type-I & II), stellar winds (“fast” O star through “slow” AGB winds), and HII photoionization. Here, we show that these feedback mechanisms drive galactic winds with outflow rates as high as 10 20 times the galaxy star formation rate. The mass-loading efficiency (wind mass loss rate divided by the star formation rate) scales roughly as _ Mwind= _ M / V 1 c (where Vc is the galaxy circular velocity), consistent with simple momentum-conservation expectations. We use our suite of simulations to study the relative contribution of each feedback mechanism to the generation of galactic winds in a range of galaxy models, from SMC-like dwarfs and Milky-way analogues to z 2 clumpy disks. In massive, gas-rich systems (local starbursts and high-z galaxies), radiation pressure dominates the wind generation. By contrast, for MW-like spirals and dwarf galaxies the gas densities are much lower and sources of shock-heated gas such as supernovae and stellar winds dominate the production of large-scale outflows. In all of our models, however, the winds have a complex multi-phase structure that depends on the interaction between multiple feedback mechanisms operating on different spatial and time scales: any single feedback mechanism fails to reproduce the winds observed. We use our simulations to provide fitting functions to the wind mass-loading and velocities as a function of galaxy properties, for use in cosmological simulations and semi-analytic models. These differ from typically-adopted formulae with an explicit dependence on the gas surface density that can be very important in both low-density dwarf galaxies and high-density gas-rich galaxies.

Subfields: Astronomy and Astrophysics, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/f5f022e5c847b90c5cb1db0e04a811337bf42664

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Citations in the corpus

Galaxies on FIRE (Feedback In Realistic Environments): stellar feedback explains cosmologically inefficient star formation (2013, methodology): “…galaxy simulations, that these mechanisms produce a quasisteady ISM in which GMCs form and disperse rapidly, with phase structure, turbulence, and disk and GMC properties in good agreement with observations (for various comparisons, see Narayanan & Hopkins 2012; Hopkins et al. 2012b,a, 2013c).”
How Stellar Feedback Simultaneously Regulates Star Formation and Drives Outflows (2015, background): “…mass is converted into stars per orbital time and the KennicuttSchmidt relation (Schmidt 1959; Kennicutt 1998) can be reproduced (e.g.Stinson et al. 2006; Shetty & Ostriker 2008, 2012; Kim et al. 2011; Ostriker & Shetty 2011; Hopkins et al. 2012b, 2014; Kim et al. 2013; Agertz & Kravtsov 2015a).”
The difficulty of getting high escape fractions of ionizing photons from high-redshift galaxies: A view from the FIRE cosmological simulations (2015, methodology): “…factions implies that the ionizing 6 Previous studies also showed that GMC lifetimes and integrated star formation efficiencies were nearly independent of the instantaneous density threshold and star formation efficiency in dense gas, as long as the clouds were resolved (Hopkins et al. 2011, 2012).”
MOMENTUM INJECTION BY SUPERNOVAE IN THE INTERSTELLAR MEDIUM (2014, methodology): “…subject to global effects, since the superbubble that forms can expand beyond the scale height of the surrounding ISM and break out of the disk, venting into the galactic halo (e.g., Mac Low et al. 1989; Tenorio-Tagle et al. 1990; Hopkins et al. 2012a) and limiting further expansion within the ISM.”
Mapping stellar content to dark matter haloes using galaxy clustering and galaxy–galaxy lensing in the SDSS DR7 (2015, background): “…characterised by the central stellar-to-halo mass ratio Mcen∗ /Mh, rises sharply as a function of halo mass at the low mass scale, probably due to the increasing difficulty for the stellar feedback to drive cold gas out of the steepening gravitational potential wells of halos (Hopkins et al. 2012).”
EVIDENCE FOR WIDE-SPREAD ACTIVE GALACTIC NUCLEUS-DRIVEN OUTFLOWS IN THE MOST MASSIVE z ∼ 1–2 STAR-FORMING GALAXIES (2014, background): “…of Mg ii absorber occurrence and profiles as a function of inclination of the host galaxy (Bordoloi et al. 2011; Kacprzak et al. 2011, 2012; Bouché et al. 2012), as well as theoretical work on both energy and momentum driven outflows (Veilleux et al. 2005; Murray et al. 2005; Hopkins et al. 2012).”
Cool outflows in galaxies and their implications (2020, background): “It has been suggested that, in order to drive cool outflows efficiently in the context of galaxy evolution, several of these mechanisms need to operate simultaneously (Hopkins et al. 2012).”
The structure of the interstellar medium of star‐forming galaxies (2011, methodology): “In Hopkins et al. (2011) (hereafter Paper I) we developed a new numerical model for the effects of the momentum injection from massive stars on small scales in star-forming regions.”
Theoretical Challenges in Galaxy Formation (2016, background): “Alternative models link the accretion rates to gravitational instabilities and torques (Hopkins et al. 2012, Hopkins & Quataert 2011).”
Metallicity gradients in local field star-forming galaxies: insights on inflows, outflows, and the coevolution of gas, stars and metals (2015, background): “The later is favoured by recent smoothedparticle hydrodynamics + N-body simulations on both galactic and cosmological scales (e.g.,Davé et al. 2011a,b; Hopkins et al. 2012), but the two mechanisms dominating in galaxies of different masses has also been suggested (Dutton & van den Bosch 2009).”
Physical Models of Galaxy Formation in a Cosmological Framework (2014, background): “Hopkins et al. (2012a) also found that in simulations of isolated disks (not cosmological) with a suite of physically motivated stellar feedback physics, even large clumps mostly blow themselves apart while in the disk, thereby only modestly contributing to spheroid growth.”
A general class of Lagrangian smoothed particle hydrodynamics methods and implications for fluid mixing problems (2012, methodology): “We also compare the massloading of galactic winds in each simulation, defined as in Hopkins et al. (2012a) as the ratio of total “wind mass” (material with positive Bernoulli parameter, i.e. which will be unbound in the absence of external pressure forces) to new stellar mass formed since the…”
A new class of accurate, mesh-free hydrodynamic simulation methods (2014, background): “In these models, rather than attempt to resolve the ISM structure or feedback explicitly, the ISM is parameterized by an “effective equation of state (EOS)” at high densities (n & 0.1cm−3), with an adjustable law which turns gas into stars at a fixed efficiency of∼ 1% per gas dynamical time (tuned t”
THE SINS/zC-SINF SURVEY of z ∼ 2 GALAXY KINEMATICS: OUTFLOW PROPERTIES (2012, background): “Hopkins et al. (2012) have recently carried out high-resolution SPH simulations of isolated galaxies with different types of input feedback, including that from supernovae, stellar winds, expanding HII regions and radiation pressure and find an overall scaling of η ∝ v−1d Σ −1/2 gas and η ∼ 1 for…”