ATOMS: ALMA three-millimeter observations of massive star-forming regions – II. Compact objects in ACA observations and star formation scaling relations

Abstract

<jats:title>ABSTRACT</jats:title> <jats:p>We report studies of the relationships between the total bolometric luminosity (Lbol or LTIR) and the molecular line luminosities of J = 1 − 0 transitions of H13CN, H13CO+, HCN, and HCO+ with data obtained from ACA observations in the ‘ATOMS’ survey of 146 active Galactic star-forming regions. The correlations between Lbol and molecular line luminosities $L^{\prime }_{\rm mol}$ of the four transitions all appear to be approximately linear. Line emission of isotopologues shows as large scatters in Lbol–$L^{\prime }_{\rm mol}$ relations as their main line emission. The log(Lbol/$L^{\prime }_{\rm mol}$) for different molecular line tracers have similar distributions. The Lbol-to-$L^{\prime }_{\rm mol}$ ratios do not change with galactocentric distances (RGC) and clump masses (Mclump). The molecular line luminosity ratios (HCN-to-HCO+, H13CN-to-H13CO+, HCN-to-H13CN, and HCO+-to-H13CO+) all appear constant against Lbol, dust temperature (Td), Mclump, and RGC. Our studies suggest that both the main lines and isotopologue lines are good tracers of the total masses of dense gas in Galactic molecular clumps. The large optical depths of main lines do not affect the interpretation of the slopes in star formation relations. We find that the mean star formation efficiency (SFE) of massive Galactic clumps in the ‘ATOMS’ survey is reasonably consistent with other measures of the SFE for dense gas, even those using very different tracers or examining very different spatial scales.</jats:p>

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions – V. Hierarchical fragmentation and gas dynamics in IRDC G034.43+00.24

“…In this paper, we present our new ALMA 3 mm observations to-wards IRDC G34, which is part of the ATOMS survey 2 (Project ID: 2019.1.00685.S, Liu et al 2020bLiu et al ,c, 2021 Paper I, Paper II, and Paper III, respectively, see Sect. 2).…”

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- XI. From inflow to infall in hub-filament systems

“…We use ALMA data from the ATOMS survey (Project ID: 2019.1.00685.S; PI: Tie Liu). The details of the 12m array and 7m array ALMA observations were summarised in Liu et al (2020aLiu et al ( , 2021. Calibration and imaging were carried out using the CASA software package version 5.6 (McMullin et al 2007).…”

“…To this end, here we conduct a statistical study of a large hubfilament sample across various evolutionary phases for investigating the relation between hub-filaments and high-mass star formation using the H 13 CO+ J=1-0 molecular line data from ALMA Threemillimeter Observations of Massive Star-forming regions (ATOMS) survey (Liu et al 2020a). We describe the detailed observations and data used in this paper in section 2.…”

ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions-IX. A pilot study towards IRDC G034.43+00.24 on multi-scale structures and gas kinematics

“…The MM1 and MM2 clumps of G34 are covered in the observations of the target source I18507+0121 from the ATOMS survey. The de-tailed descriptions about the scientific goals of the survey, observing setups and data reduction can be found in Liu et al (2020bLiu et al ( ,c, 2021 and Paper II. In this paper, we only make use of the 12m+ACA combined data of H 13 CO + (1-0).…”

“…In this paper, the third in the series of studies on IRDC G34 (Liu et al 2020a, 2022, hereafter Paper I, andPaper II, respectively) and also a pilot study of multi-scale structures and kinematics using interferometric data from the ATOMS survey 1 (Project ID: 2019.1.00685.S, Liu et al 2020b,c, 2022, we aim to investigate the kinematics of density structures at different scales through the exemplary G34 cloud. In Paper I, we analysed in great detail the chemical components of nine protostellar clumps (i.e., MM1-MM9, see Fig.…”