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TRICEPS. I. Tracing cold gas, dust, and stars at sub-kpc scales in massive star-forming galaxies at z = 4-5

Year: 2026
Type: preprint
Abstract: We introduce the TRICEPS (Tracing Resolved Ionized Carbon Emission in Primeval Systems) survey. TRICEPS focuses on a sample of 16 massive galaxies at z = 4 - 5 with top-quality data: (i) ALMA band-7 observations of the [CII]-158 micron line, tracing the cold gas distribution and kinematics at spatial resolutions of about 0.1" (~0.8 kpc), (ii) ALMA maps of the rest-frame 160 micron continuum emission, tracing the dust distribution at similar spatial resolutions, (iii) multi-band JWST images from NIRCam and MIRI, tracing the stellar mass distribution and star formation activity at spatial resolutions of 0.1"-0.2", and (iv) multi-line CO observations from ALMA and the VLA, including the CO(1-0) line, tracing the molecular gas content. In this first paper, we describe the TRICEPS scientific goals, the basic properties of the galaxy sample, and the ALMA band-7 observations. TRICEPS galaxies were selected based only on bright [CII] fluxes (>2 Jy km/s). They lie on the top-end of the star-forming main sequence at z = 4-5, having stellar masses between about 10^10.5-10^12 Msun and star-formation rates between about 100 - 3000 Msun/yr. To date, TRICEPS is the largest sample of galaxies at z = 4-5 for which the gas distribution and kinematics are exceptionally well resolved: on average, 46 resolution elements per galaxy with signal-to-noise ratio higher than 3. By survey design, half of the TRICEPS targets are in galaxy pairs; clear signs of tidal interactions are present in three of the four pairs. In all galaxies, the [CII] velocity fields display regular rotation, albeit the interacting galaxies tend to be somewhat more disturbed. The TRICEPS observations suggest that regular rotation is ubiquitous among massive star-forming galaxies when the Universe was less than ~1.5 Gyr old.
DOI: 10.48550/arxiv.2609.30375
Authors: Lelli, Federico, Lin, Lingrui, Zhang, Zhi-Yu, Bacchini, Cecilia, Bevacqua, Davide, Bhangal, Joe, Castellano, Marco, De Breuck, Carlos, Gandolfi, Giovanni, Man, Allison W. S., Marasco, Antonino, Paris, Diego, Pérez-Díaz, Borja, Santini, Paola
Institutions: University of Cagliari, Arcetri Astrophysical Observatory, National Institute for Astrophysics, Nanjing University, University of Copenhagen, Osservatorio Astronomico di Padova, Astronomical Observatory of Rome, University of British Columbia, European Southern Observatory
Language: English
Open Access status: green
Funders: National Science Foundation, National Radio Astronomy Observatory, Carlsbergfondet, Korea Astronomy and Space Science Institute, National Astronomical Observatory of Japan, Canadian Space Agency, Natural Sciences and Engineering Research Council of Canada, National Institutes of Natural Sciences
OpenAlex ID: W7214603129
Cites: 4
Cited by: 1
Related to: 10