Environment of MAMBO galaxies in the COSMOS field

TL;DR

This study identifies significant galaxy overdensities around MAMBO-detected submillimeter galaxies in the COSMOS field, indicating that a substantial fraction of bright SMGs at z=1.4-2.5 form in dense environments during peak star formation epoch.

Contribution

It reports the discovery of galaxy overdensities associated with SMGs, providing evidence for their evolution into cluster spheroidal galaxies.

Findings

Compact galaxy overdensities are statistically significant.

Photometric redshifts of galaxies in overdensities match SMG redshifts.

Approximately 30% of bright SMGs at z=1.4-2.5 are in dense environments.

Abstract

Submillimeter galaxies (SMG) represent a dust-obscured high-redshift population undergoing massive star formation activity. Their properties and space density have suggested that they may evolve into spheroidal galaxies residing in galaxy clusters. In this paper, we report the discovery of compact (~10"-20") galaxy overdensities centered at the position of three SMGs detected with the Max-Planck Millimeter Bolometer camera (MAMBO) in the COSMOS field. These associations are statistically significant. The photometric redshifts of galaxies in these structures are consistent with their associated SMGs; all of them are between z=1.4-2.5, implying projected physical sizes of ~170 kpc for the overdensities. Our results suggest that about 30% of the radio-identified bright SMGs in that redshift range form in galaxy density peaks in the crucial epoch when most stars formed.