Towards ALMA2040: An update from the European community and invitation to contribute

Abstract

Over the last 15 years, the Atacama Large Millimeter/submillimeter Array (ALMA) has revolutionized astrophysics by providing unprecedented resolution and sensitivity in observing the cold universe, including the formation of stars, planets, and galaxies. With groundbreaking discoveries ranging from the first detailed images of protoplanetary disks to the kinematics of galaxies in the Epoch of Reionization, ALMA has showcased the vast discovery potential of the (sub-)mm wavelength regime. However, in another 15 years from now--in the 2040s--the science landscape will have changed dramatically as new major observational facilities will have started their operations or have come towards advanced maturity in their scientific outcome (e.g., JWST, Rubin Observatory, ELT, Euclid, Gaia, Plato, Ariel, Roman Space Telescope, SPHEREx, LiteBIRD, LISA, SKA and others). At the same time, ALMA's current Wideband Sensitivity Upgrade will have been in place for ~10 years, and ALMA itself will have been operational for 30 years. To fully exploit this era, the community needs a next-generation facility operating at (sub-)mm wavelengths with capabilities far beyond those possible within ALMA's current infrastructure. To this end, ALMA2040 is a community-driven initiative to define the key scientific questions of the 2040s and translate them into a technical vision for a next-generation transformational (sub-)millimeter facility. Our goal with this document is to summarize the current status of the effort, synthesize outcomes from the 2025 workshops, outline next steps toward a reference design concept, and invite broad participation from the global mm/sub-mm community to help shape this future facility. In the following we provide details on the process and scope. We invite everyone who wishes to join the effort and/or contribute to the dedicated White Papers planned for 2026.