The EDGE-CALIFA Survey: An integral field unit-based integrated molecular gas database for galaxy evolution studies in the Local Universe

TL;DR

This paper introduces the iEDGE database, combining optical and molecular gas data for 643 local galaxies, enabling comprehensive studies of galaxy evolution and star formation processes.

Contribution

The paper presents a homogenized, integrated database of galaxy properties from multiple telescopes, facilitating new insights into galaxy evolution and star formation.

Findings

Bi-modal star formation relationships across galaxy types

Homogeneous decrease of molecular gas fraction in different galaxy types

Inner regions of passive galaxies show significantly lower star formation efficiency

Abstract

Studying galaxy evolution requires knowledge not only of the stellar properties, but also of the interstellar medium (in particular the molecular phase) out of which stars form, using a statistically significant and unbiased sample of galaxies. To this end, we introduce here the integrated Extragalactic Database for Galaxy Evolution (iEDGE), a collection of integrated stellar and nebular emission lines, and molecular gas properties from 643 galaxies in the local Universe. These galaxies are drawn from the CALIFA datasets, and are followed up in CO lines by the APEX, CARMA, and ACA telescopes. As this database is assembled from data coming from a heterogeneous set of telescopes (including IFU optical data and single-dish and interferometric CO data), we adopted a series of techniques (tapering, spatial and spectral smoothing, and aperture correction) to homogenise the data. Due to the application of these techniques, the database contains measurements from the inner regions of the galaxies and for the full galaxy extent. We used the database to study the fundamental star formation relationships between star formation rate (SFR), stellar mass ($M_*$), and molecular gas mass ($M_{\rm mol}$) across galaxies with different morphologies. We observed that the diagrams defined by these quantities are bi-modal, with early-type passive objects well separated from spiral star-forming galaxies. Additionally, while the molecular gas fraction ($f_{\rm mol}=M_{\rm mol}/M_*$) decreases homogeneously across these two types of galaxies, the star formation efficiency (SFE=SFR/$M_{\rm mol}$) in the inner regions of passive galaxies is almost two orders of magnitude lower compared to the global values. This indicates that inside-out quenching requires not only low $f_{\rm mol}$, but also strongly reduced SFE in the galactic centres.