부산대학교 도서관

Massive galaxy-scale outflows of gas are one of the most commonly-invokedmechanisms to regulate the growth and evolution of galaxies throughout theuniverse. While the gas in outflows spans a large range of temperatures anddensities, the cold molecular phase is of particular interest because molecularoutflows may be capable of suppressing star formation in galaxies by removingthe star-forming gas. We have conducted the first survey of molecular outflowsat z > 4, targeting 11 strongly-lensed dusty, star-forming galaxies (DSFGs)with high-resolution Atacama Large Millimeter Array (ALMA) observations of OH119um absorption as an outflow tracer. In this first paper, we give an overviewof the survey, focusing on the detection rate and structure of molecularoutflows. We find unambiguous evidence for outflows in 8/11 (73%) galaxies,more than tripling the number known at z > 4. This implies that molecular windsin z > 4 DSFGs must have both a near-unity occurrence rate and large openingangles to be detectable in absorption. Lensing reconstructions reveal that500pc-scale clumpy structures in the outflows are common. The individual clumpsare not directly resolved, but from optical depth arguments we expect thatfuture observations will require 50-200pc spatial resolution to do so. We donot detect high-velocity [CII] wings in any of the sources with clear OHoutflows, indicating that [CII] is not a reliable tracer of molecular outflows.Our results represent a first step toward characterizing molecular outflows atz > 4 at the population level, demonstrating that large-scale outflows areubiquitous among early massive, dusty galaxies.