Deviations from the Schmidt-Kennicutt relations during early galaxy evolution

TL;DR

This study uses advanced galaxy evolution models to show that early galaxies often deviate from the standard Schmidt-Kennicutt relations, highlighting limitations of these relations in simulating early universe star formation.

Contribution

The paper introduces detailed, time-varying models including CO-bright H_2 and realistic star formation feedback, providing more accurate tracking of early galaxy evolution and deviations from S-K relations.

Findings

Galaxies show significant deviations from S-K relations during early evolution.

Deviations are more pronounced in gas-rich and metal-poor systems.

These deviations suggest limitations of S-K relations in early universe simulations.

Abstract

We utilize detailed time-varying models of the coupled evolution of stars and the HI, H_2, and CO-bright H_2 gas phases in galaxy-sized numerical simulations to explore the evolution of gas-rich and/or metal-poor systems, expected to be numerous in the Early Universe. The inclusion of the CO-bright H_2 gas phase, and the realistic rendering of star formation as an H_2-regulated process (and the new feedback processes that this entails) allows the most realistic tracking of strongly evolving galaxies, and much better comparison with observations. We find that while galaxies eventually settle into states conforming to Schmidt-Kennicutt (S-K) relations, significant and systematic deviations of their star formation rates (SFRs) from the latter occur, especially pronounced and prolonged for ... ...This indicates potentially serious limitations of (S-K)-type relations as reliable sub-grid elements of star formation physics in simulations of structure formation in the Early Universe. We anticipate that galaxies with marked deviations from the S-K relations will be found at high redshifts as unbiased inventories of total gas mass become possible with ALMA and the EVLA.