THE ROLE OF STELLAR FEEDBACK IN THE FORMATION OF GALAXIES

By D. Ceverino, Anatoly Klypin. 2007

224 citations recorded by the source corpus.

Although supernova (SN) explosions and stellar winds happen at very small scales, they affect the interstellar medium (ISM) at galactic scales and regulate the formation of a whole galaxy. Previous attempts of mimicking these effects in simulations of galaxy formation use very simplified assumptions. We develop a much more realistic prescription for modeling the feedback, which minimizes any ad hoc subgrid physics. We start with developing high-resolution models of the ISM and formulate the conditions required for its realistic functionality: formation of multiphase medium with hot chimneys, superbubbles, cold molecular phase, and very slow consumption of gas. We find that this can be achieved only by doing what the real universe does: formation of dense (>10 H atoms cm−3), cold (T ≈ 100 K) molecular phase, where the star formation happens, and which young stars disrup. Another important ingredient is the effect of runaway stars: massive binary stars ejected from molecular clouds when one of the companions becomes an SN. Those stars can move to 10–100 pc away from molecular clouds before exploding themselves as SNe. This greatly facilitates the feedback. Once those effects are implemented into cosmological simulations, galaxy formation proceeds more realistically. For example, we do not have the overcooling problem. The angular momentum problem (resulting in a too massive bulge) is also reduced substantially: the rotation curves are nearly flat. The galaxy formation also becomes more violent. Just as often observed in quasar absorption lines, there are substantial outflows from forming and active galaxies. At high redshifts we routinely find gas with few hundred km s−1 and occasionally 1000–2000 km s−1. The gas has high metallicity, which may exceed the solar metallicity. The temperature of the gas in the outflows and in chimneys can be very high: T = 107–108 K. The density profile of dark matter is still consistent with a cuspy profile. The simulations reproduce this picture only if the resolution is very high: better than 50 pc, which is 10 times better than the typical resolution in previous cosmological simulations. Our simulations of galaxy formation reach the resolution of 35 pc.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/ca4e7a589451f41ed52ed87e40b1574b295bc7ac

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In Astronomy and Astrophysics

1. P. Hopkins
2. Volker Springel
3. L. Hernquist
4. R. Dav'e
5. T. Naab
6. Simon D. M. White
7. E. Quataert
8. A. Dekel

Citations in the corpus

• THE ARECIBO LEGACY FAST ALFA SURVEY. X. THE H i MASS FUNCTION AND FROM THE 40% ALFALFA SURVEY (2010, background): “…the missing satellite problem (Simon & Geha 2007), but it remains difficult to fully simulate baryons in forming and evolving galaxies (Governato et al. 2007; Mayer et al. 2008; Ceverino & Klypin 2009; Gnedin et al. 2009), and it is therefore important to develop other observational constraints.”
• Small scale problems of the $\Lambda$CDM model: a short review (2016, background): “6 Consistent with [58] assumptions; the threshold >10/cm3 [297] marks the limit for bulk gas flows.”
• Cuspy No More: How Outflows Affect the Central Dark Matter and Baryon Distribution in Lambda CDM Galaxies (2012, background): “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).”
• FORMATION OF MASSIVE GALAXIES AT HIGH REDSHIFT: COLD STREAMS, CLUMPY DISKS, AND COMPACT SPHEROIDS (2009, methodology): “The code incorporates the relevant physical processes, including atomic and molecular gas cooling and photoionization heating, star formation, metal enrichment, and feedback from stars and supernovae, as described in Ceverino & Klypin (2009).”
• High-resolution panchromatic spectral models of galaxies including photoionization and dust (2009, methodology): “One of the current issues in the model is the lack of treatment for the cold phase ISM.”
• The confinement of star-forming galaxies into a main sequence through episodes of gas compaction, depletion and replenishment (2015, methodology): “The VELA simulations utilize the Adaptive Refinement Tree (ART) code (Kravtsov et al. 1997; Kravtsov 2003; Ceverino & Klypin 2009), which accurately follows the evolution of a gravitating N -body system and the Eulerian gas dynamics.”
• TOWARD A COMPLETE ACCOUNTING OF ENERGY AND MOMENTUM FROM STELLAR FEEDBACK IN GALAXY FORMATION SIMULATIONS (2012, background): “Ceverino & Klypin (2009) argued that a very large fraction of a cell’s mass must be converted into stars for feedback heating to overcome the radiative cooling for gas at T = 104 K, where the cooling function peaks.”
• Theoretical Challenges in Galaxy Formation (2016, background): “…galaxy formation simulations allow for metal enrichment and metal dependent radiation equilibrium cooling (for specific implementations see e.g. Ceverino & Klypin 2009; Kravtsov 2003; Oppenheimer & Davé 2006; Scannapieco et al. 2005; Tornatore et al. 2007; Vogelsberger et al. 2013; Wiersma,…”
• Compaction and quenching of high-z galaxies in cosmological simulations: blue and red nuggets (2014, methodology): “Supernovae and stellar winds are implemented by local injection of thermal energy as in Ceverino & Klypin (2009); Ceverino, Dekel & Bournaud (2010); Ceverino et al. (2012).”
• X-shooter reveals powerful outflows in z ∼ 1.5 X-ray selected obscured quasi-stellar objects (2014, background): “…galaxies (e.g. without an AGN at the center), for which generally velocities larger than 500-600 km/s are not expected (e.g. Murray et al. 2005; Ceverino & Klypin 2009; Lagos et al. 2013; but see Diamond-Stanic et al. 2012 for a different conclusion, which, however, applies only to galaxies…”
• The Core-Cusp Problem (2009, result): “Note though that in a recent analysis, Ceverino and Klypin [123] perform similar calculations, but find that halos remain cuspy, and suggest that differences in the simulation approach might be responsible for this.”
• Numerical simulations of the dark universe: State of the art and the next decade (2012, background): “Feedback appears to be a crucial ingredient in explaining the macroscopic properties of individual galaxies [337, 352–355] as well as galaxy population statis-”
• Damped Lyman α systems in galaxy formation simulations (2008, background): “Promising progress in placing such winds on a more physical footing was recently described by Ceverino & Klypin (2007), whose simulations reproduce such bulk motions starting from an explicit model for the ISM.”