ARRAKIHS simulation of the low surface brightness features in the halo of a spiral galaxy like the Milky Way. Credit: Alex Camazón (IEEC) / AMC
The European Space Agency (ESA) has officially adopted ARRAKIHS as a scientific mission, confirming the target launch date of 2030. Matthieu Schaller is part of the science team: “I look forward to learning more about the dark part of our cosmos.”
ESA’s adoption follows the successful completion of key conceptual and preliminary design milestones, including the Preliminary Design Review (PDR) of the instrument and the delivery of the “Red Book,” the definition study report describing the scientific, technical and programmatic implementation of ARRAKIHS.
Revealing the faint universe
Selected by ESA in 2022, ARRAKIHS (Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys) was conceived to provide new insights into one of the major open questions in modern astrophysics: how galaxies form and evolve within the Standard Model of Cosmology.
The low-surface-brightness diffuse stellar halos around galaxies like the Milky Way preserve crucial information about how galaxies formed and evolved, revealing the combined effects of dark matter, galaxy mergers and other processes that shape galaxies over cosmic time. “Many of these structures are extremely faint and difficult to study systematically with existing observations,” explains Rebekka Coles-Bieri (UZH), the mission’s science coordinator.
ARRAKIHS will thus open a new observational window onto the largely unexplored low-surface-brightness universe, enabling the study of previously hidden stellar components of the galaxy halos.
Members of the ARRAKIHS instrument team working on the scientific payload. Credit: Satlantis/ IDR/ UPM
An international collaboration
ARRAKIHS is being developed through a collaboration between ESA and the ARRAKIHS Mission Consortium (AMC), led by Prof. Rafael Guzmán from the Instituto de Física de Cantabria (IFCA, CSIC-UC).
The consortium includes more than 250 scientists and engineers from seven ESA member states led by Spain, including Austria, Belgium, Norway, Portugal, Sweden and Switzerland, together with additional contributions from institutions and companies in the United Kingdom, France, Denmark, the Netherlands, the United States, Taiwan and Thailand.
Testing models of dark matter with observations
Researchers from Leiden University are involved in the science team. According to Matthieu Schaller, the ARRAKIHS mission is shaping up to be a key test bed for our understanding of the cosmological model, especially the nature of dark matter.
“I am very excited about this new ESA mission. Mapping the halo of nearby galaxies in detail will reveal crucial information about the nature of the mysterious dark matter particle,” he says. “Different models of dark matter predict different shapes of the gravitational potential well. The Leiden team is involved in making these predictions via supercomputer simulations using state-of-the-art models for galaxy formation and dark matter. These predictions will be tested via the observations of ARRAKIHS.”
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From concept to adopted mission
Over the past few years, the international ARRAKIHS consortium has transformed a highly ambitious scientific concept into a fully established space mission within ESA’s Science Programme. This progress has been supported by major scientific and technological achievements, including developing new, high-resolution cosmological simulations and galaxy models; the design of key subsystems of the flight instrument; the initial development of the ground-based infrastructure for scientific data and data analysis systems; and the operation of a ground demonstrator camera installed at the Javalambre Astrophysical Observatory, as well as the acquisition of increasingly deep observations that further strengthen the mission’s scientific case.
With its official adoption by ESA, ARRAKIHS is now entering the construction phase in preparation for its launch in 2030.
Key concepts
CosmologyGalaxy dark matter halos
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ESA officially adopts ARRAKIHS mission: EU leads the exploration of the low surface brightness universe (2026, June 11)
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