Abstract

We report 18 dust continuum detections (>= 3.3 sigma) at similar to 88 and 158 mu m out of 49 ultraviolet (UV)-bright galaxies (M-UV < -21.3 mag) at z > 6.5, observed by the Cycle-7 Atacama Large Millimeter/submillimeter Array (ALMA) Large Program, Reionization-Era Bright Emission Line Survey (REBELS) and its pilot programs. This has more than tripled the number of dust continuum detections known at z > 6.5. Out of these 18 detections, 12 are reported for the first time as part of REBELS. In addition, 15 of the dust continuum detected galaxies also show a [C II](158 mu m) emission line, providing us with accurate redshifts. We anticipate more line emission detections from six targets (including three continuum detected targets) where observations are still ongoing. We estimate that all of the sources have an infrared (IR) luminosity (L IR) in a range of 3-8 x10(11) L-circle dot. except for one with L-IR = 1.5(-0.5)(+0.8) x10(12) L-circle dot. Their fraction of obscured star formation is significant at greater than or similar to 50 per cent, despite being UV-selected galaxies. Some of the dust continuum detected galaxies show spatial offsets (similar to 0.5-1.5 arcsec) between the rest-UV and far-IR emission peaks. These separations could imply spatially decoupled phases of obscured and unobscured star formation, but a higher spatial resolution observation is required to confirm this. REBELS offers the best available statistical constraints on obscured star formation in UV-luminous galaxies at z > 6.5.