ECOGAL I. Project design and the first catalogue

TL;DR

ECOGAL addresses the need to uniformly mine ALMA archival data in tandem with JWST and HST footprints to study the cold ISM and obscured star formation across cosmic time. By constructing a robust, multi-wand dataset that combines a prior-based and a blind ALMA catalogue with JWST/DJA and 3D-HST redshift information, the study delivers science-ready continuum maps and extensive redshift coverage up to $z\sim15$. Key contributions include a detailed data-processing pipeline (ALMA retrieval, imaging, and photometry), meticulous astrometric alignment, and a multi-tracer approach to star formation including Balmer decrement and [N II] corrections in high-redshift galaxies, along with an assessment of line-contamination impacts. The first release expands parameter space with the UDS field, enables exploration of cosmic gas/dust evolution, obscured star formation, and optically dark sources, and provides a community-ready resource for advancing galaxy evolution studies.

Abstract

We present ECOology for Galaxies using ALMA archive and Legacy surveys (ECOGAL), an ALMA data mining project. Using the footprints of the James Webb Space Telescope (JWST) and the Hubble Space Telescope (HST), we query and uniformly reprocess ALMA data to produce continuum images and two complementary source catalogues: (i) a prior-based catalogue anchored to optical/near-infrared detections, and (ii) a blind catalogue based on significant ALMA detections. Detection thresholds are established through peak SNR statistics and analysis of inverted maps. In this paper, we focus on the ALMA-accessible CANDELS fields (COSMOS, GOODS-S, and UDS), covering ~130,000 optical/NIR-selected galaxies spanning $0.0 < z < 15.0$. We identify 1288 detections (622 unique) with optical/NIR counterparts across the two methods, of which 832 detections (395 unique) appear in both. Among the 622 unique sources, 307 have spectroscopic redshifts from $0.12 < z < 6.85$. ECOGAL expands the parameter space previously explored by $A^3COSMOS$ and $A^3GOODS-S$ by incorporating the UDS field and integrating publicly available JWST datasets from the DAWN JWST Archive (DJA). We also highlight several science cases enabled by ECOGAL, including the evolution of cosmic gas and dust masses, obscured star formation and optically dark systems. ECOGAL provides science-ready data sets for the community and showcases the power of combining over a decade of accumulated public data with other legacy datasets. The data product is made publicly available and accompanies a post demonstrating the usage of the catalogue on the DJA webpage.

Figures (19)

• Figure 1: ALMA observations in the GOODS-S region used for the first data release (shown as grey polygons). Only single-pointing observations are included. Concentric circles indicate multiple band/depth observations for the same target. The blue rectangle outlines the 3D-HST F140W coverage, while the orange polygon marks the JWST F444W mosaic footprint from DJA. The dashed line shows the ALMA archive query region, chosen to encompass the full 3D-HST and JWST coverage.
• Figure 2: Flux comparison for detected sources using the three extraction and measurement methods, colour-coded by SNR. Overall, the three methods show good mutual agreement.
• Figure 3: Spurious fraction for the prior (left) and blind (right) source detections as a function of peak SNR. The cumulative spurious fraction indicates the fraction of spurious detections above a given $SNR_{\rm peak}$ threshold. We adopt detection thresholds of $SNR_{\rm peak}=5.1$ for the prior-based catalogue and $6.6$ for the blind catalogue, yielding a differential spurious fraction below $<$50%.
• Figure 4: Redshift distribution of ALMA-covered sources from the parent catalogue and of ALMA-detected sources. ALMA-detected galaxies are mainly located at $z\sim2.5$. The two ALMA detections with photometric redshifts $z>9$ are likely lower-redshift sources missing photometry at $>2\,\mu$m in the parent catalogue.
• Figure 5: Stacked histogram of the spectral lines that fall within the ALMA bandwidth for each redshift bin, shown for the spectroscopically confirmed sample.