# An ALMA survey of the brightest sub-millimetre sources in the SCUBA-2 COSMOS field

**Authors:** J. M. Simpson, Ian Smail, U. Dudzeviciute, Y. Matsuda, B. -C. Hsieh, W. -H. Wang, A. M. Swinbank, S. M. Stach, Fang Xia An, J. E. Birkin, Y. Ao, A. J. Bunker, S. C. Chapman, Chian-Chou Chen, K. E. K. Coppin, S. Ikarashi, R. J. Ivison, I. Mitsuhashi, T. Saito, H. Umehata  
**arXiv:** [2003.05484](https://arxiv.org/abs/2003.05484)  
**Date:** 2020-03-11  
**Summary page:** https://www.summarizepaper.com/en/paper/2003.05484v1/

## Key points

- ALMA survey focused on brightest sub-millimeter sources in COSMOS field from S2COSMOS survey
- Pilot study for larger AS2COSMOS survey aiming to investigate approximately 1,000 sources
- Multiple SMG counterparts detected in significant percentage of sub-millimeter sources, higher association rate for brighter secondary SMGs
- Bright [CII] 157.74um line emission discovered in two SMGs at redshift z=4.63
- Interferometric 870um number counts constructed and multiwavelength spectral energy distribution analyzed for each AS2COSMOS SMG
- MAGPHYS used to model emission, estimate photometric redshifts, and show evidence for evolution in bright-end of 870um luminosity function across sample

## Summary

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In this study, we present an ALMA survey focusing on the brightest sub-millimeter sources in the COSMOS field from the S2COSMOS survey. This pilot study serves as a precursor to the larger AS2COSMOS survey, which aims to investigate approximately 1,000 sources in this region. Our observations reveal that more than one SMG counterpart was detected in a significant percentage of sub-millimeter sources, with a higher association rate for brighter secondary SMGs. Additionally, we discovered bright [CII] 157.74um line emission in two SMGs at redshift z=4.63, associated with the highest significance single-dish source. We also constructed interferometric 870um number counts and utilized archival data to analyze the multiwavelength spectral energy distribution of each AS2COSMOS SMG. By modeling this emission using MAGPHYS, we estimated photometric redshifts and found strong evidence for evolution in the bright-end of the 870um luminosity function across our sample. Overall, this comprehensive study sheds light on the properties and evolution of sub-millimeter galaxies in the COSMOS field and sets the stage for further investigations through the upcoming AS2COSMOS survey.