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  • Images of galaxies of the local universe obtained with small aperture telescopes showing the detection of EMFs of different morphologies. Credits: D. Martínez-Delgado.
  • Simulation of the halo of one of the galaxies that will be observed in the ARRAKIHS mission. Credits: Alex Camazón (ARRAKIHS Consortium).

Understanding the nature of dark matter

The "Analysis of Resolved Remnants of Accreted galaxies as a Key Instrument for Halo Surveys" (ARRAKIHS) mission will image the nearby Universe down to an unprecedented ultra-low surface brightness simultaneously in two visible and two infrared bands. Selected in November 2022 as a Fast-class mission of ESA's Science Programme, ARRAKIHS is a small satellite with an innovative telescope system that is expected to be launched in 2030 in Low Earth Orbit.

An ESA mission to explore the low surface brightness Universe

ARRAKIHS will allow us to address major outstanding issues in the Λ-Cold Dark Matter (ΛCDM) cosmological model. In particular, if Dark Matter in our Universe deviates from the cold and collisionless model as for the standard ΛCDM.

The ARRAKIHS mission will test predictions of ΛCDM by observing a volume-limited and flux-limited sample of nearby MW-galaxy haloes down to ultra-low surface brightness at visible and infrared wavelengths.  ARRAKIHS will specifically: (i) characterise the abundance and locations of satellite galaxies, down to MV < -6 for a complete sample of MW-like galaxies beyond the Local Group (ii) provide robust statistics of the numbers and shapes of wide and thin stellar streams, and (iii) characterise the shape and extent of the ultra-faint IHL. The background, observational/technical requirements, and anticipated results for each of these study areas is outlined below.

The research team responsible for ARRAKIHS will be led by Rafael Guzmán, CSIC researcher, member of the IFCA Observational Cosmology and Instrumentation Group and professor at the University of Florida, the Complutense University of Madrid (UCM), the Institute of Astrophysics of Andalusia ( IAA-CSIC), the Institute of Space Sciences (ICE-CSIC), the Institute for Space Studies of Catalonia (IEEC), the Center for Astrobiology (CAB, INTA-CSIC) and the Center for Physics of the Cosmos of Aragon (CEFCA), in collaboration with the company Satlantis.

Satlantis' iSIM binocular camera will allow imaging of the universe at ultra-low surface brightness in four visible and infrared bands. Credits: Satlantis.

ICE-CSIC's participation

The ICE-CSIC provides major contributions in Instrumentation and Science for the ARRAKIHS mission. ICE-CSIC currently coordinates the main instrument of the payload, with contributions from an international ARRAKIHS consortium. Additionally, contributions to the Fine Guidance System and characterization of the visible and infrared detectors are expected to be supported by ICE-CSIC and its facilities. On the Science side, the Cosmology group is contributing with unique Cosmological Simulations, as well as participating in the ESA Science Study Team.

Senior institute members involved

Meet the senior researchers who lead our participation in the ARRAKIHS mission.

  • Santiago Serrano

    Santiago Serrano

  • Pablo Fosalba

    Pablo Fosalba

  • Francisco J. Castander

    Francisco J. Castander

  • Enrique Gaztañaga

    Enrique Gaztañaga

  • Ricard Casas

    Ricard Casas