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

Abstract

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 (λ~1.3 mm). In conjunction with data obtained from the ALMA-ATOMS survey at Band 3 (λ~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 (~0.3 arcsec) 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, H30α, 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.

The ALMA-QUARKS Survey. II. The ACA 1.3 mm Continuum Source Catalog and the Assembly of Dense Gas in Massive Star-Forming Clumps

“…The targeted lines included, but were not limited to: (1) outflow tracers (e.g., CO, 13 CO, SiO, SO, H 2 CO); (2) cold gas tracer (N 2 D + ); (3) dense core and filament tracers (e.g., C 18 O, HC 3 N); (4) hot core tracers (e.g., CH 3 OH, C 2 H 5 CN, NH 2 CHO, CH 3 CN); (5) ionized-gas/HII-region tracer (H 30 α). The basics of the main targeted lines are summarized in Table 2 of Liu et al (2023b).…”

“…Line emission channels were flagged to obtain the continuum and spectral lines simultaneously. Liu et al (2023b) identified all the transitions of strong lines within the four SPWs by matching the reduced data cubes of the ALMA pipeline and the laboratory databases for the spectral lines (CDMS; Müller et al 2001). The QUARKS team generated a model spectrum as a mask for line emission channels.…”

“…The QUARKS survey updates the clump distances using the H 13 CO + lines of the ATOMS survey and the latest model for the rotation curve of the Milky Way (Reid et al 2019), as listed in Table A. of Liu et al (2023b). At the bottom right of Figure 1, both the angular and physical scale bars are shown, with updated clump distance.…”

“…We collect the QUARKS clump mass M clump and radius R clump from Liu et al (2023b) and plot them (orange stars) with ACA fragments (blue pentagons) in Figure 4. The source extraction algorithm of the clumps is the same as we do for ACA fragments, so there is no systematic bias due to the methodology in the following discussion.…”

“…Therefore, we performed a 1.3 mm ALMA survey called "Querying Underlying mechanisms of massive star formation with ALMA-Resolved gas Kinematics and Structures" (QUARKS; PIs: Lei Zhu, Guido Garay and Tie Liu; Project ID: 2021.1.00095.S). The details of the survey description and the showcase of data combinations can be found in Liu et al (2023b).…”