The ALMA-QUARKS Survey. I. Survey Description and Data Reduction

This paper presents an overview of the QUARKS survey, which stands for 'Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures'. The QUARKS survey is observing 139 massive gas clumps covered by 156 pointings at ALMA Band 6 (lambda similar to 1.3 mm). In conjunction with data obtained from the ALMA-ATOMS survey at Band 3 (lambda similar to 3 mm), QUARKS aims to carry out an unbiased statistical investigation of massive star formation process within protoclusters down to a scale of 1000 au. This overview paper describes the observations and data reduction of the QUARKS survey, and gives a first look at an exemplar source, the mini-starburst Sgr B2(M). The wide-bandwidth (7.5 GHz) and high-resolution (similar to 0.'' 3) observations of the QUARKS survey allow to resolve much more compact cores than could be done by the ATOMS survey, and to detect fainter filamentary structures that were not revealed earlier. The spectral windows cover transitions of species including CO, SO, N2D+, SiO, H30 alpha, H2CO, CH3CN and many other complex organic molecules, tracing gas components with different temperatures and spatial extents. QUARKS aims to deepen our understanding of several scientific topics of massive star formation, such as mass transport within protoclusters by (hub-)filamentary structures, the existence of massive starless cores, the physical and chemical properties of dense cores within protoclusters, and the feedback from already formed high-mass young protostars.