FOSSIL: A future mission for CMB spectral distortion measurements
astro-ph.CO, astro-ph.IM, hep-ph
Submitted: 2026-09-14
Updated: 2026-09-14
Comments: 36 pages, 11 figures
License: http://creativecommons.org/licenses/by/4.0/
The gist: We present FOSSIL, a proposed space mission which is designed to deliver unprecedented absolute spectroscopic measurements of the sky intensity over a broad frequency range (50GHz to 2THz) to
Terminology
Abstract
We present FOSSIL, a proposed space mission which is designed to deliver unprecedented absolute spectroscopic measurements of the sky intensity over a broad frequency range (50GHz to 2THz) to accurately measure chemical-potential mu-type, Compton y-type, and Compton relativistic y-type CMB spectral distortions. FOSSIL will reach monopole sensitivities representing a gain of roughly three orders of magnitude over COBE/FIRAS. These capabilities will allow us to constrain primordial density fluctuations on scales k (10 to 10 4)Mpc-1, test inflationary models, probe dark matter annihilation/decay/interactions, constrain primordial black hole seed scenarios, and pin down feedback models in galaxy evolution and structure formation by measuring the cosmic thermal energy content. Furthermore, its 130 spectral channels will enable legacy astrophysics, including precise characterisation of the Cosmic Infrared Background, line intensity mapping during cosmic noon, and detailed Galactic dust mapping.
Sources
- Line-Intensity Mapping
- Thermalization of large energy release in the early Universe
- Improved frequency hierarchy treatment for anisotropic spectral distortions
- CMB Spectral Distortion Anisotropies from Acoustic Damping with primordial non-Gaussianity
- A new constraint on the $y$-distortion with FIRAS: implications for feedback models in galaxy formation and cosmic shear measurements
- Line-Intensity Mapping: 2017 Status Report
- First detection of the WIM dust emission. Implication for the Cosmic Far-Infrared Background
- Evidence for dust emission in the Warm Ionised Medium using WHAM data
- The COSmic Monopole Observer (COSMO)
- PRISM (Polarized Radiation Imaging and Spectroscopy Mission): A White Paper on the Ultimate Polarimetric Spectro-Imaging of the Microwave and Far-Infrared Sky
- A new constraint on the $y$-distortion with FIRAS: robustness of component separation methods
- Performance characterization of a new Structural and Thermal Architecture for a future spaceborne Closed-Cycle Dilution Refrigerator
- Hydrodynamic methods and sub-resolution models for cosmological simulations
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