GLADEnet is a progressive web app for multi-messenger cosmology and electromagnetic follow-ups of gravitational-wave sources. It is a software tool designed to assist astronomers in the identification and prioritization of host galaxies for transient astrophysical events, particularly in the context of gravitational-wave (GW) follow-up. It extends the capabilities of the GLADE (Galaxy List for the Advanced Detector Era) catalog by providing queryable access, filtering tools, and integration with sky-localization maps, allowing users to efficiently match transient event skymaps with likely host galaxies. Knowing which galaxies are most likely to host such events helps observatories optimize their follow-up campaigns. GLADEnet bridges the gap between wide-area GW localizations and the targeted, narrow field of view of most EM telescopes.
Key Features
Interactive real-time completeness assessment. Enables the identification of catalogued galaxies and dynamically evaluates the completeness level of the GLADE+ catalogue within the gravitational-wave localization region.
Filtering: with interactive sliders to filter galaxies based on absolute magnitude or probability density (dp/dV) within the 90% credible volume.
Completeness estimation based on Schechter luminosity function. Computes the completeness by comparing the observed total luminosity in the localization volume to the expected luminosity derived from a Schechter function fit to the catalogue data. This feature is applicable even in low-latency GW event follow-ups in real time.
Use Cases:
Empowering Galaxy Catalogs for Multimessenger Applications. GLADEnet enhances the use of galaxy catalogues in the follow-up of gravitational-wave (GW) sources by providing an interactive, real-time visualization of the most probable candidate host galaxies consistent with the event localization. Users can apply dynamic filters based on relevant astrophysical parameters (e.g., absolute magnitude, redshift) within the event’s credible volume. This approach enables an informed and rapid selection of the most promising EM counterparts, thereby maximizing observational efficiency and the likelihood of correctly identifying the host galaxy.
Standard Siren Cosmology. By associating gravitational-wave (GW) events with galaxies of known redshift, GLADEnet enables cosmological measurements—such as the determination of the Hubble constant (H₀)—through the standard siren approach. This capability extends also to binary black hole mergers, where no electromagnetic (EM) counterpart is expected, by supporting the dark standard siren method, which relies on statistical associations with galaxy catalogues rather than direct host identification.
GLADEnet is a critical tool for targeted electromagnetic (EM) follow-up of gravitational-wave (GW) events. It efficiently associates localization maps (3d skymaps) with potential host galaxies and prioritizes observations based on the probability of association, thereby enhancing the speed and accuracy of multi-messenger discovery campaigns—especially within the short time window following a GW detection.
An additional strength of GLADEnet lies in its ability to support the choice of observational strategy, which is optimized according to galaxy catalogue completeness and the observable magnitude threshold. The optimal strategy depends on both the sky localization area and the catalogue’s level of completeness. In cases of low completeness, it is necessary to cover the entire localization region using wide-field telescopes, due to the lack of catalogued galaxies. Conversely, when completeness is high, it is preferable to use telescopes with narrower fields of view to target the most promising galaxies directly. In this framework, GLADEnet can be used to: 1) promote targeted (punctual) surveys, 2) maximize the efficiency of follow-up campaigns, 3) identify sky regions that are currently under-observed or catalogued incompletely, thereby contributing to the overall improvement of catalogue completeness.
Once observational campaigns have been completed, newly collected data can be directly uploaded to the VizieR data server through the dedicated upload service, which facilitates the preparation and integration of new catalogues.