Environment of MAMBO galaxies in the COSMOS field

Submillimeter galaxies (SMGs) 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 Letter, 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 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 = 1.4and2.5, 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. Based on observations obtained, within the COSMOS Legacy Survey, with the IRAM 30 m, NRAO-VLA, Hubble Space Telescope (HST), Canada-France-Hawaii Telescope (CFHT), Subaru, KPNO, Cerro Tololo Inter-American Observatory (CTIO), and ESO Observatories. The National Radio Astronomy Observatory is a facility of the National Science Foundation (NSF), operated under cooperative agreement by Associated Universities Inc