Maximally Star-forming Galactic Disks. Ii. Vertically Resolved Hydrodynamic Simulations of Starburst Regulation
Year: 2012
Type: article
Abstract: We explore the self-regulation of star formation using a large suite of high-resolution hydrodynamic simulations, focusing on molecule-dominated regions (galactic centers and [U]LIRGS) where feedback from star formation drives highly supersonic turbulence. In equilibrium, the total midplane pressure, dominated by turbulence, must balance the vertical weight of the interstellar medium. Under self-regulation, the momentum flux injected by feedback evolves until it matches the vertical weight. We test this flux balance in simulations spanning a wide range of parameters, including surface density Σ, momentum injected per stellar mass formed ( p * / m * ), and angular velocity. The simulations are two-dimensional radial–vertical slices, and include both self-gravity and an external potential that helps to confine gas to the disk midplane. After the simulations reach a steady state in all relevant quantities, including the star formation rate Σ SFR , there is remarkably good agreement between the vertical weight, the turbulent pressure, and the momentum injection rate from supernovae. Gas velocity dispersions and disk thicknesses increase with p * / m * . The efficiency of star formation per free-fall time at the midplane density, ff ( n 0 ), is insensitive to the local conditions and to the star formation prescription in very dense gas. We measure ff ( n 0 ) ∼ 0.004–0.01, consistent with low and approximately constant efficiencies inferred from observations. For Σ ∈ (100–1000) M ☉ pc −2 , we find Σ SFR ∈ (0.1–4) M ☉ kpc −2 yr −1 , generally following a Σ SFR ∝ Σ 2 relationship. The measured relationships agree very well with vertical equilibrium and with turbulent energy replenishment by feedback within a vertical crossing time. These results, along with the observed Σ–Σ SFR relation in high-density environments, provide strong evidence for the self-regulation of star formation.
Source: The Astrophysical Journal
Authors: Rahul Shetty, Eve C. Ostriker
Institutions: Heidelberg University, University of Maryland, College Park
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2025199693