The EDGE-CALIFA survey: The local and global relations between $\Sigma_\ast$ , $\Sigma_{SFR}$ and $\Sigma_{mol}$ that regulate star-formation

TL;DR

This study reveals that the relationships between star-formation rate, stellar mass, and molecular gas surface densities are consistent across different spatial scales in galaxies, suggesting a unified underlying relation.

Contribution

It demonstrates that these relations are scale-invariant and can be described by a single three-dimensional relation, challenging the idea of scale-dependent star-formation laws.

Findings

Relations are consistent across scales with similar slopes and scatter.

The three properties follow a single three-dimensional relation.

Secondary residual relations are due to measurement uncertainties, not physical differences.

Abstract

We present a new characterization of the relations between star-formation rate, stellar mass and molecular gas mass surface densities at different spatial scales across galaxies (from galaxy wide to kpc-scales). To do so we make use of the largest sample combining spatially-resolved spectroscopic information with CO observations, provided by the EDGE-CALIFA survey, together with new single dish CO observations obtained by APEX. We show that those relations are the same at the different explored scales, sharing the same distributions for the explored data, with similar slope, intercept and scatter (when characterized by a simple power-law). From this analysis, we propose that these relations are the projection of a single relation between the three properties that follows a distribution well described by a line in the three-dimension parameter space. Finally, we show that observed secondary relations between the residuals and the considered parameters are fully explained by the correlation between the uncertainties, and therefore have no physical origin. We discuss these results in the context of the hypothesis of self-regulation of the star-formation process.