CHAMPS: The COSMOS High-Redshift ALMA-MIRI Population Survey - A New Census of the Dusty Early Universe

Understanding how dust forms and evolves across cosmic time is a key open problem in extragalactic astrophysics. Early-universe galaxies were once thought to be mostly dust-poor, but recent discoveries of heavily dust-obscured galaxies near the Epoch of Reionization challenge models of early dust production and raise questions about the true cosmic star formation rate density. The COSMOS High-Redshift ALMA-MIRI Population Survey (CHAMPS) targets this dusty early universe at z>4.

CHAMPS is a new 144-hour ALMA 1.2 mm (band 6) large program mapping the combined JWST/NIRCam+MIRI footprint in the COSMOS field. It covers 0.2 deg² with a synthesized beam size of 1.1 arcsec and a sensitivity of 0.14 mJy/beam, and is complemented, alongside JWST, by ancillary X-ray, UV, optical, submillimeter, and radio data. The survey was optimized as a blind survey.

Above 5σ, CHAMPS detects approximately 385 individual dusty high-redshift submillimeter sources, 68 dusty AGN, and a dozen dusty galaxies at z>6. The galaxies are largely not detected in JWST/F150W, making them prototypical near-infrared dark galaxies. The paper showcases three of the highest-redshift, most dusty, and most massive candidate galaxies detected in CHAMPS, with redshifts up to z=7.5.

CHAMPS also enables stacks of thousands of galaxies grouped in bins of various physical parameters. Its submillimeter coverage of dust-attenuated JWST-identified galaxies provides robust constraints on dust masses and obscured star formation rates for studying early dust formation and evolution. In addition, it enables a blind search for luminous CO line emitters at z=0.4–2.7 and [CII] 158 μm emitters at z=6.7.