Kiloparsec-scale Simulations of Star Formation in Disk Galaxies. IV. Regulation of Galactic Star Formation Rates by Stellar Feedback

Abstract

Star formation from the interstellar medium of galactic disks is a basic process controlling the evolution of galaxies. Understanding the star formation rate (SFR) in a local patch of a disk with a given gas mass is thus an important challenge for theoretical models. Here we simulate a kiloparsec region of a disk, following the evolution of self-gravitating molecular clouds down to subparsec scales, as they form stars that then inject feedback energy by dissociating and ionizing UV photons and supernova explosions. We assess the relative importance of each feedback mechanism. We find that H 2 -dissociating feedback results in the largest absolute reduction in star formation compared to the run with no feedback. Subsequently adding photoionization feedback produces a more modest reduction. Our fiducial models that combine all three feedback mechanisms yield, without fine-tuning, SFRs that are in excellent agreement with observations, with H 2 -dissociating photons playing a crucial role. Models that only include supernova feedback-a common method in galaxy evolution simulations-settle to similar SFRs, but with very different temperatures and chemical states of the gas, and with very different spatial distributions of young stars.

The Physical Origin of Long Gas Depletion Times in Galaxies

“…The mass fraction of star-forming gas and its distribution is also a nontrivial function of the feedback strength and the specific mix of processes that define it (e.g., Hopkins et al 2013b;Butler et al 2017). Stronger feedback shortens the time that gas spends in the star-forming state, t sf , and, therefore, decreases the mass fraction of star-forming gas: f sf ≡ M sf /M g ∼ t sf /(t nsf + t sf ).…”

Herschel-HOBYS study of the earliest phases of high-mass star formation in NGC 6357

“…Persi & Tapia 2008) the gas removal timescale would then be longer. In addition, NGC 6357 follows qualitatively the evolutionnary picture of the star formation (at kpc scale) with EUV and SN feedback as simulated by Butler et al (2017). They show that feedback tends to disperse the clustering of the star-formation and to reduce the star formation rate (especially when the mechanical feedback from radiation and supernovae is combined).…”

Numerical Methods for Simulating Star Formation

“…Currently, numerous studies and projects are based on a similar setup, with increasing physics put on over several years (SNe, radiative feedback, cosmic-rays, shear, etc. ): the series of papers by Hennebelle and Iffrig (2014), Iffrig and Hennebelle (2017), and Colling et al (2018) as well as the work of Martizzi et al (2016) and Butler et al (2015Butler et al ( , 2017 using RAMSES, by Kim et al (2011), Kim et al (2013), Kim and Ostriker (2015), Kim and Ostriker (2017), and Kim and Ostriker (2018) using ATHENA, the SILCC project papers using FLASH (Walch et al, 2015;Girichidis et al, 2016Girichidis et al, , 2018Gatto et al, 2017;Peters et al, 2017).…”