Do Submillimeter Galaxies Trace Megaparsec Large-scale Structures? -- An Overdensity Analysis of 449 Submillimeter Galaxies in COSMOS

@misc{deng2026submillimeter,
  title = {{Do Submillimeter Galaxies Trace Megaparsec Large-scale Structures? -- An Overdensity Analysis of 449 Submillimeter Galaxies in COSMOS}},
  author = {Canze Deng and Daizhong Liu and Helmut Dannerbauer and Gianluca Castignani and Rosa Calvi and Lauro Moscardini and Benjamin Magnelli and Sylvia Adscheid and Eva Schinnerer and Hui Li and Rafael Arango-Toro and Caitlin Casey and Jacky S. W. Chan and Andreas Faisst and Maximilien Franco and Zohreh Ghaffari and Santosh Harish and Jeyhan Kartaltepe and Greta Toni and Jorge Zavala and Xin Zeng and Xianzhong Zheng},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.01136},
  eprint = {2610.01136},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.01136},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Do Submillimeter Galaxies Trace Megaparsec Large-scale Structures? -- An Overdensity Analysis of 449 Submillimeter Galaxies in COSMOS
AU  - Canze Deng
AU  - Daizhong Liu
AU  - Helmut Dannerbauer
AU  - Gianluca Castignani
AU  - Rosa Calvi
AU  - Lauro Moscardini
AU  - Benjamin Magnelli
AU  - Sylvia Adscheid
AU  - Eva Schinnerer
AU  - Hui Li
AU  - Rafael Arango-Toro
AU  - Caitlin Casey
AU  - Jacky S. W. Chan
AU  - Andreas Faisst
AU  - Maximilien Franco
AU  - Zohreh Ghaffari
AU  - Santosh Harish
AU  - Jeyhan Kartaltepe
AU  - Greta Toni
AU  - Jorge Zavala
AU  - Xin Zeng
AU  - Xianzhong Zheng
PY  - 2026
DA  - 2026/10/01
PB  - arXiv
DO  - 10.48550/arxiv.2610.01136
UR  - https://arxiv.org/abs/2610.01136
AB  - We present an environmental analysis and overdensity catalog for a large sample of submillimeter galaxies (SMGs) in the COSMOS field in order to understand whether SMGs are signposts of megaparsec-scale overdensity structures. We apply the Poisson Probability Method (PPM) protocluster finder to characterize the significance (σ) and overdensity value (δ) of any overdense structures surrounding specific 'beacon' galaxies. These beacons include 449 SMGs from A3COSMOS (including 168 with spectroscopic redshifts, 52 of which have CO or [CII] 158μm line detections), as well as a control sample of over 5000 main-sequence star-forming galaxies (SFGs) selected from the 40-band photometric-redshift catalog in COSMOS2025. We successfully reproduce 15 known protoclusters and clusters in COSMOS (including Hyperion large-scale structure, CL J1001+0220 at z~2.5, and AzTEC-3 protocluster at z~5.3), and report 26 new PPM-based high-overdensity (δ ≥ 5), high-significance (σ ≥ 5), robust candidates. We measure an overdensity fraction of 11.5-71.2% (1.3-61.0%) in the CO/[CII] 52 SMG (full 449 SMG) sample with different criterion categories, confirming that SMGs are signposts of overdensities compared to the control SFG sample. We also notice that the fraction is lower than 100%, indicating that not all SMGs are associated with overdensities. We thus inspect the JWST morphology and argue that the triggering of starburst in SMGs must have non-environmental mechanisms, for instance, merger and violent disk instability. Finally, we further conduct a spatial distribution analysis, finding that the location of SMGs in overdensities has a redshift evolution, with SMGs being more concentrated in the inner regions of overdensities at higher redshift.
ER  -