# Submillimeter Galaxies do trace Galaxy Protoclusters

**Authors:** R. Calvi, G. Castignani, H. Dannerbauer  
**arXiv:** [2302.10323](https://arxiv.org/abs/2302.10323)  
**Date:** 2023-02-20  
**Summary page:** https://www.summarizepaper.com/en/paper/2302.10323v1/

## Key points

- Controversy surrounding whether dusty starbursts selected at submillimeter wavelengths can accurately trace galaxy overdensities
- Systematic search for protoclusters around 12 spectroscopically confirmed submillimeter galaxies (SMGs) in the GOODS-N field
- Poisson Probability Method (PPM) and three photometric redshift catalogs used to identify Mpc-scale overdensities around SMGs
- Galaxy overdensities detected for 11 out of 12 SMGs, distributed across eight protoclusters
- Three previously discovered protoclusters confirmed and five new ones identified
- SMGs reside in protocluster cores with diverse morphologies such as compact, filamentary, or clumpy structures
- Protoclusters at lower redshifts tend to be populated by dusty galaxies, while those at higher redshifts are characterized by Lyman-alpha emitters or Lyman break galaxies
- Correlation established between molecular gas mass of SMGs and significance of associated overdensities
- Submillimeter galaxies are excellent tracers of distant protoclusters and potential targets for future observations with James Webb Space Telescope, Euclid, and LSST.

## Summary

The controversy surrounding whether dusty starbursts selected at submillimeter wavelengths can accurately trace galaxy overdensities is addressed in this study. The authors conducted a systematic search for protoclusters around a sample of 12 spectroscopically confirmed submillimeter galaxies (SMGs) in the GOODS-N field, with redshifts ranging from approximately 1.2 to 5.3. Using the Poisson Probability Method (PPM) and three photometric redshift catalogs, the researchers identified Mpc-scale overdensities around these SMGs. They successfully detected galaxy overdensities for 11 out of the 12 SMGs, distributed across eight protoclusters. Additionally, they confirmed three previously discovered protoclusters and identified five new ones associated with specific SMGs. A wavelet-based analysis revealed that the SMGs reside in protocluster cores exhibiting diverse morphologies such as compact, filamentary, or clumpy structures. On average, these cores have sizes of approximately 0.4-1 Mpc. By comparing the PPM results obtained using different redshift catalogs independently, the authors observed a potential transitioning phase for galaxy populations at redshifts greater than or equal to 4. Interestingly, they found that protoclusters at lower redshifts (less than approximately 4) tend to be populated by dusty galaxies while those at higher redshifts (around 5) are characterized by overdensities of Lyman-alpha emitters or Lyman break galaxies. Furthermore, a correlation was established between the molecular gas mass of the SMGs and the significance of their associated overdensities; suggesting that interactions between galaxies in dense environments likely triggered both the starburst activity and gas-rich phase observed in these SMGs. Overall, this study supports the notion that submillimeter galaxies are excellent tracers of distant protoclusters and provides evidence for their potential as targets for future observations with facilities like James Webb Space Telescope and upcoming surveys conducted by Euclid and LSST which can be optimized to detect even larger samples of distant protoclusters.