2020ApJ...904....2G

Previous studies measuring the clustering of submillimeter galaxies (SMGs) have based their measurements on single-dish-detected sources, finding evidence for strong clustering. However, ALMA has revealed that, due to the coarse angular resolution of these instruments, single-dish sources can be composed of multiple sources. This implies that the clustering inferred from single-dish surveys may be overestimated. Here, we measure the clustering of SMGs based on the ALESS survey, an ALMA follow-up of sources previously identified in the LABOCA ECDFS Submillimeter Survey (LESS). We present a method to measure the clustering of ALMA sources that have been previously identified using single-dish telescopes, based on forward modeling both the single-dish and the ALMA observations. We constrain upper limits for the median mass of halos hosting SMGs at 1 < z < 3, finding M_halo≤ 2.4×10¹²M_☉ for SMGs with flux densities S₈₇₀≥ 4.0 mJy, which is at least 3.8_–2.6^+3.8 times lower than the mass inferred based on the clustering of the LESS sources alone. This suggests that the strength of SMG clustering based on single-dish observations was overestimated, and therefore SMGs might be hosted by dark matter halos less massive than has previously been estimated. By extrapolating our models down to flux densities of S₈₇₀≥ 1.2 mJy, we find that such SMGs inhabit halos with median mass M_halo≤ 3.2×10¹¹M_☉. We conclude that only the brightest (S₈₇₀≳5-6mJy) SMGs would trace massive structures at z ∼ 2 and only SMGs with S₈₇₀≳6 mJy may be connected to massive local elliptical galaxies, quasars at intermediate redshifts, and high-redshift star-forming galaxies, whereas fainter SMGs are unlikely linked to these populations.