ARRAKIHS Mission
Contents
The ARRAKIHS mission
Mission scope
ARRAKIHS consortium
The ARRAKIHS mission
On November 2, 2022, the European Space Agency (ESA) announced the new F-class space mission for its scientific program: ARRAKIHS (Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys). ARRAKIHS bring light to the enigma of the nature of dark matter, that in our Universe is five times more abundant than ordinary matter, according to the current cosmological models.
To achieve this, ARRAKIHS will observe the local Universe at very low levels of surface brightness in visible and infrared wavelengths, using a set of high-precision cameras aboard a satellite that will orbit around Earth at an altitude of around 800 km. Currently, ARRAKIHS mission is in its initial stages (phaseA/B), having passed with success the payload phase B on march 2024. The ARRAKIHS community is working tirelessly to pass all evaluations and secure formal adoption as ESA’s F2 mission by mid-2026, with a planned launch in 2029-2030.
The ARRAKIHS mission will assess the significance of reported tensions between predictions of the Cold Dark Matter (CDM) cosmological model at galaxy halo scales, the current implementation of baryon physics (BP) in galaxy formation models and the observed properties from ground-based observatories of the haloes of the Milky Way (MW) and Andromeda Galaxies.
Through deep simultaneous, visible and infrared imaging of a statistically representative sample of nearby haloes of MW-type galaxies in the local Universe, down to unprecedented low surface brightness. ARRAKIHS will provide key tests with statistical significance to probe wether the reported tensions are the result of selection effects and/or small number statistics. However, if the tensions are confirmed with these new observations, ARRAKIHS will demonstrate de inconsistency in the theoretical models of MW-type galaxy formation based on current implementation of CDM+BP, and thus such models must be changed or replaced.
The ARRAKIHS mission has three main observational goals: to provide robust statistics of the numbers and shapes of wide and thin tidal stellar structures, to characterise the shape and extent of the ultra-faint intra-halo light and to determine the abundance and locations of satellite galaxies, for a complete sample of MW-like galaxies beyond the Local Group.
Mission Scope
The mission’s scope involves imaging a vast expanse of the sky during three years, covering approximately 50 square degrees each year across two visible bands and two infrared bands at an unprecedented ultra-low surface brightness. These high-resolution images will be crucial to address unresolved questions within the ΛCDM cosmological framework.
To carry out this mission, two innovative binocular cameras iSIM-170 developed by the company Satlantis will be used. Each of these cameras consists of two telescopes with f/10 and 150 mm diameter housing four filters covering the full range from 400 nm to 1700 nm. The iSIM camera design has been successfully validated in space both on the International Space Station (ISS) and aboard micro-satellites, demonstrating the best available image quality for satellites weighing below 500 kg. In the initial phase of ARRAKIHS, a version of iSIM-170 will be used for observations from the Javalambre Observatory to demonstrate its image quality and refine both the observational strategy and image processing.
The survey will culminate in the creation of a unique catalogue of ultra-low surface brightness extragalactic images, focusing on a volume-limited and mass-limited sample of galaxies akin to our own Milky Way. ARRAKIHS will achieve an unparalleled surface brightness sensitivity, capturing details down to 30 mag/arcsecond² with a resolution of 1.5 arcseconds (FWHM) in visible wavelengths and 29 mag/arcsecond² with 2.5 arcseconds (FWHM) in near-infrared wavelengths.
The ARRAKIHS Consortium
The ARRAKIHS Mission Consortium (AMC) is a collective of creative, passionate, innovative, and ambitious individuals collaborating to achieve the common goal of launching a fast space mission with the scientific objective of understanding the nature of dark matter. Comprising scientists, engineers, PhD students, technical and management professionals, the Consortium continuously expands in both size and expertise, working together in the best collaborative way.
The AMC is the group of people from different research institutes and companies representing seven European countries (Spain, Austria, Belgium, Sweden and Switzerland). Other European countries are currently in the process of joining the AMC (Portugal, UK and Norway). These countries are collectively referred to as the “Member States” and they are responsible for the Science, Instrument and Science Data Center funding, design and operation. The ARRAKIHS Mission Consortium also includes research institutes from three non-European countries: United States, Thailand and Taiwan and also includes European aerospace companies in Spain, Switzerland, Belgium, and the United Kingdom .