Galactic outflows of molecular gas are a common occurrence in galaxies and may represent a mechanism by which galaxies self-regulate their growth, redistributing gas that could otherwise have formed stars. We previously presented the first survey of molecular outflows at z > 4 towards a sample of massive, dusty galaxies. Here we characterize the physical properties of the molecular outflows discovered in our survey. Using low-redshift outflows as a training set, we find agreement at the factor-of-two level between several outflow rate estimates. We find molecular outflow rates 150-800Msun/yr and infer mass loading factors just below unity. Among the high-redshift sources, the molecular mass loading factor shows no strong correlations with any other measured quantity. The outflow energetics are consistent with expectations for momentum-driven winds with star formation as the driving source, with no need for energy-conserving phases. There is no evidence for AGN activity in our sample, and while we cannot rule out deeply-buried AGN, their presence is not required to explain the outflow energetics, in contrast to nearby obscured galaxies with fast outflows. The fraction of the outflowing gas that will escape into the circumgalactic medium (CGM), though highly uncertain, may be as high as 50%. This nevertheless constitutes only a small fraction of the total cool CGM mass based on a comparison to z~2-3 quasar absorption line studies, but could represent >~10% of the CGM metal mass. Our survey offers the first statistical characterization of molecular outflow properties in the very early universe.

We present CO J=4-3 line and 3 mm dust continuum observations of a 100 kpc-scale filamentary Ly{\alpha} nebula (SSA22 LAB18) at z=3.1 using the Atacama Large Millimeter/submillimeter Array (ALMA). We detected the CO J=4-3 line at a systemic z(CO)=3.093 {\pm} 0.001 at 11 {\sigma} from one of the ALMA continuum sources associated with the Ly{\alpha} filament. We estimated the CO J=4-3 luminosity of L'CO(4-3)=(2.3\pm0.2)x10^9 K km s^{-1} pc^2 for this CO source, which is one order of magnitude smaller than those of typical z>1 dusty star-forming galaxies (DSFGs) of similar far-infrared luminosity L(IR)~10^{12} Lsun. We derived a molecular gas mass of Mgas=(4.4^{+0.9}_{-0.6})x10^9 Msun and a star-formation rate of SFR=270\pm160 Msun yr^{-1}. We also estimated a gas depletion time of {\tau}(dep)=17\pm10 Myr, being shorter than those of typical DSFGs. It is suggested that this source is in a transition phase from DSFG to a gas-poor, early-type galaxy. From ALMA to Herschel multi-band dust continuum observations, we measured a dust emissivity index {\beta}=2.3\pm0.2, which is similar to those of local gas-poor, early-type galaxies. Such a high {\beta} can be reproduced by specific chemical compositions for interstellar dust at the submillimeter wavelengths from recent laboratory experiments. ALMA CO and multi-band dust continuum observations can constrain the evolutionary stage of high-redshift galaxies through {\tau}(dep) and {\beta}, and thus we can investigate dust chemical compositions even in the early Universe.

Massive galaxy-scale outflows of gas are one of the most commonly-invoked mechanisms to regulate the growth and evolution of galaxies throughout the universe. While the gas in outflows spans a large range of temperatures and densities, the cold molecular phase is of particular interest because molecular outflows may be capable of suppressing star formation in galaxies by removing the star-forming gas. We have conducted the first survey of molecular outflows at z > 4, targeting 11 strongly-lensed dusty, star-forming galaxies (DSFGs) with high-resolution Atacama Large Millimeter Array (ALMA) observations of OH 119um absorption as an outflow tracer. In this first paper, we give an overview of the survey, focusing on the detection rate and structure of molecular outflows. We find unambiguous evidence for outflows in 8/11 (73%) galaxies, more than tripling the number known at z > 4. This implies that molecular winds in z > 4 DSFGs must have both a near-unity occurrence rate and large opening angles to be detectable in absorption. Lensing reconstructions reveal that 500pc-scale clumpy structures in the outflows are common. The individual clumps are not directly resolved, but from optical depth arguments we expect that future observations will require 50-200pc spatial resolution to do so. We do not detect high-velocity [CII] wings in any of the sources with clear OH outflows, indicating that [CII] is not a reliable tracer of molecular outflows. Our results represent a first step toward characterizing molecular outflows at z > 4 at the population level, demonstrating that large-scale outflows are ubiquitous among early massive, dusty galaxies.