A catalog to unite them all: REGALADE, a revised galaxy compilation for the advanced detector era

TL;DR

REGALADE tackles the need for a complete, high-purity all-sky galaxy catalog to enable time-domain and multi-messenger astrophysics by unifying diverse surveys and distance indicators. It employs Gaia-based star removal, cross-catalog ellipse homogenization, multi-stage photometry retrieval, and a visual validation step to produce nearly 80 million galaxies with robust distances and a large fraction having stellar masses and ellipse fits. The catalog demonstrates superior completeness and host-identification performance for supernovae, GW events, and ULX/HLX hosts compared with prior resources, and includes extensive publicly available data, classifications, and code. This work provides a practical, scalable foundation for rapid follow-up, population studies, and cosmological inferences in the era of LSST, Euclid, and next-generation GW detectors.

Abstract

Many applications in transient science, gravitational wave follow-up, and galaxy population studies require all-sky galaxy catalogs with reliable distances, extents, and stellar masses. However, existing catalogs often lack completeness beyond $\sim 100$ Mpc, suffer from stellar contamination, or do not provide homogeneous stellar mass estimates and size information. Our goal is to build a high-purity, high-completeness, all-sky galaxy catalog out to 2,000 Mpc, specifically designed to support time-domain and multi-messenger astrophysics. We combined major galaxy catalogs and deep imaging surveys -- including the Legacy Surveys, Pan-STARRS, DELVE, and SDSS -- and added spectroscopic, photometric, and redshift-independent distances. We cleaned the sample using the Gaia catalog to remove stars and visually inspected all ambiguous cases below 100 Mpc through a classification platform that gathered 27,000 expert votes. Stellar masses were estimated using optical and mid-infrared profile-fit photometry, and we improved the accuracy of photometric distances by combining multiple independent estimates. The resulting catalog, REGALADE, includes nearly 80 million galaxies with distances under 2,000 Mpc. It provides stellar masses for 88% of the sample and ellipse fits for 80%. REGALADE is more than 90% complete for galaxies contributing 50% of the total $r$-band luminosity out to 360 Mpc. In science tests, it recovers 60% more known supernova hosts, doubles the number of low-luminosity transient hosts, and identifies more reliable hosts for ultraluminous and hyper-luminous X-ray sources. REGALADE is one of the most complete and reliable all-sky galaxy catalog to date for the nearby Universe, built for real-world applications in transient and multi-messenger astrophysics. The full dataset, visual classifications, and code will be released to support broad community use.

Figures (18)

• Figure 1: Parameter space used to identify stellar contaminants, for GLADE+ (top left) and DELVE (top right, bottom) objects. Galaxies (blue dots) shown in these plots are objects that appear in at least four input catalogs. Stars (yellow dots) are identified as objects in at most two catalogs that have a Gaia counterpart located within a separation of $s < 2$ arc seconds and exhibit a proper motion greater than 5 mas/yr. The yellow-shaded region highlights the parameter space selected to isolate Gaia stars, which for the top panels is defined by the condition $G - BP - 1 < \log\left(s/\text{arcsec}\right) < \min\left(\log(s_\text{max}),~ -0.5(G - BP)\right),$ where $s_\text{max} = 2.5$ for GLADE+ and 1.5 for the other catalogs. For the bottom panel, the selection follows the condition $\log\left(R_1/\text{arcsec}\right) < (24 - r_K)/10$.
• Figure 2: Comparison of galaxies in input catalogs (left) and in the final REGALADE compilation (right), for a 2.6' field centered at RA = 180.19$^\circ$, Dec = $-$0.03$^\circ$. The background is a ($g,r,i,z$) composite from Legacy Surveys DR10.
• Figure 3: Comparison between our stellar mass estimates and the Wen2024ApJS..272...39W reference values, for galaxies with distance estimates agreeing within 15% in both catalogs. The legend reports the mean difference and normalized median absolute deviation (NMAD), in dex.
• Figure 4: Screenshot of the galaxy classification platform, for a galaxy candidate at RA = 327.726$^\circ$, Dec = $-$40.995$^\circ$. The background is a ($g,r,i,z$) composite from Legacy Surveys DR10.
• Figure 5: (Top) Spatial distribution of REGALADE galaxies at $D<100$ Mpc, in equatorial frame. The black line marks the Galactic plane. (Bottom) Differences in spatial density between REGALADE and GLADE1 galaxies at $D<100$ Mpc (REGALADE excess in red, GLADE1 excess in blue).