DeGaS-MC: Dense Gas Survey in the Magellanic Clouds

Galametz, M.; Schruba, Andreas; Breuck, C. De; Immer, K.; Chevance, Mélanie; Galliano, F.; Lebouteiller, V.; Lee, Min Young; Madden, S.; Polles, F. L.; Kempen, T. A. van

doi:10.1051/0004-6361/202038641

Cited by 14 publications

(19 citation statements)

References 112 publications

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“…Comparing with the HCN J = 2 → 1 and HCO + J = 2 → 1 data from star-forming clouds of the Magellanic Clouds (Galametz et al 2020), we find that the low-metallicity environment not only slightly deviates the data from the overall surface-density correlations, but also would bias the HCN J = 2 → 1/HCO + J = 2 → 1 line ratio to low ratios. This is consistent with previous findings in low-metallicity galaxies (e.g., Braine et al 2017).…”

Section: Discussionmentioning

confidence: 57%

“…Unfortunately, it is difficult to find systematic observations of the J = 2 → 1 transition towards our Milky Way, while such observations do exist towards the Magellanic Clouds. Therefore, we compare the galaxy survey with the Magellanic Clouds data from Galametz et al (2020), who presented HCN J = 2 → 1 and HCO + J = 2 → 1 observations towards ∼30 LMC and SMC molecular clouds using APEX.…”

Section: Connecting To Star-forming Clouds On Small Scalesmentioning

confidence: 99%

“…As shown in Figure 7, after including molecular clouds of the Magellanic Clouds into our galaxy sample, the correlations between L HCN J=2→1 -L IR and L HCO + J=2→1 -L IR still hold with semi-linear slopes of 1.021 and 1.088, respectively. The upper limits of non-detections seem off the correlation, possibly due to different detection criteria in Galametz et al (2020), who consider a 3-σ peak Gaussian fitting (instead of integrated flux) as the detection threshold. We also include data of Magellanic Clouds into the correlations of surface densities, by adopting the area from (e.g., Wong et al 2011;Muller et al 2010).…”

Section: Connecting To Star-forming Clouds On Small Scalesmentioning

confidence: 99%

“…The IR emission is in general extinction-free and often covered by multi-IR-wavelength space telescopes such as Herschel (Pilbratt et al 2010), Spitzer (Werner et al 2004), Infrared Astronomical Satellite (IRAS; Neugebauer et al 1984), etc. Therefore, the total IR luminosity is widely adopted as a star-formation rate tracer for gas-rich galaxies (e.g., Galametz et al 2016Galametz et al , 2020.…”

Section: Introductionmentioning

confidence: 99%

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Dense Gas and Star Formation in Nearby Infrared Bright Galaxies: APEX survey of HCN and HCO+ J=2-1

Zhou¹,

Zhang²,

Gao³

et al. 2022

Preprint

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Both Galactic and extragalactic studies on star formation suggest that stars form directly from dense molecular gas. To trace such high volume density gas, HCN and HCO + J = 1 → 0 have been widely used for their high dipole moments, relatively high abundances, and often being the strongest lines after CO. However, HCN and HCO + J = 1 → 0 emission could be arguably dominated by the gas components at low volume densities. HCN J = 2 → 1 and HCO + J = 2 → 1, with more suitable critical densities (1.6 × 10 6 and 2.8 × 10 5 cm −3 ) and excitation requirements, would trace typical dense gas closely related to star formation. Here we report new observations of HCN J = 2 → 1 and HCO + J = 2 → 1 towards 17 nearby infrared-bright galaxies with the APEX 12-m telescope. The correlation slopes between luminosities of HCN J = 2 → 1, and HCO + J = 2 → 1 and total infrared emission are 1.03±0.05 and 1.00±0.05, respectively. The correlations of their surface densities, normalised with the area of radio/sub-millimeter continuum, show even tighter relations (Slopes: 0.99 ± 0.03 and 1.02 ± 0.03). The eight AGN-dominated galaxies show no significant difference from the eleven star-formation dominated galaxies in above relations. The average HCN/HCO + ratios are 1.15±0.26 and 0.98±0.42 for AGN-dominated and star-formation dominated galaxies, respectively, without obvious dependencies on infrared luminosity, dust temperature, or infrared pumping. The Magellanic Clouds roughly follow the same correlations, expanding to eight orders of magnitude. On the other hand, ultra-luminous infrared galaxies with active galactic nucleus (AGN) systematically lay above the correlations, indicating potential biases introduced by AGNs.

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Section: Discussionmentioning

confidence: 57%

Section: Connecting To Star-forming Clouds On Small Scalesmentioning

confidence: 99%

Section: Connecting To Star-forming Clouds On Small Scalesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dense Gas and Star Formation in Nearby Infrared Bright Galaxies: APEX survey of HCN and HCO+ J=2-1

Zhou¹,

Zhang²,

Gao³

et al. 2022

Preprint

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“…Using the same telescope, Nishimura et al (2016) reported marginal detections of N 2 H + emission in N159W and N113 despite a significant deficit of N-bearing molecules in the LMC (Millar & Herbst 1990). Measurements at millimeter/submillimeter windows (Paron et al 2016;Galametz et al 2020) detected several high-density gas tracers, HCO + , HCN, CS, and (tentative) C 18 O, toward the N159W region. Ott et al (2010) performed an NH 3 survey on such CO prominent regions, including N159W and N113, using the Australia Telescope Compact Array (ATCA).…”

Section: Introductionmentioning

confidence: 99%

An ALMA Study of the Massive Molecular Clump N159W-North in the Large Magellanic Cloud: A Possible Gas Flow Penetrating One of the Most Massive Protocluster Systems in the Local Group

Tokuda

Minami²,

Fukui

et al. 2022

ApJ

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Massive dense clumps in the Large Magellanic Cloud can be an important laboratory to explore the formation of populous clusters. We report multiscale ALMA observations of the N159W-North clump, which is the most CO-intense region in the galaxy. High-resolution CO isotope and 1.3 mm continuum observations with an angular resolution of ∼0.″25 (∼0.07 pc) revealed more than five protostellar sources with CO outflows within the main ridge clump. One of the thermal continuum sources, MMS-2, shows an especially massive/dense nature whose total H2 mass and peak column density are ∼104 M ⊙ and ∼1024 cm−2, respectively, and harbors massive (∼100 M ⊙) starless core candidates identified as its internal substructures. The main ridge containing this source can be categorized as one of the most massive protocluster systems in the Local Group. The CO high-resolution observations found several distinct filamentary clouds extending southward from the star-forming spots. The CO (1–0) data set with a larger field of view reveals a conical, ∼30 pc long complex extending toward the northern direction. These features indicate that a large-scale gas compression event may have produced the massive star-forming complex. Based on the striking similarity between the N159W-North complex and the other two previously reported high-mass star-forming clouds in the nearby regions, we propose a “teardrops inflow model” that explains the synchronized, extreme star formation across >50 pc, including one of the most massive protocluster clumps in the Local Group.

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A search for 3-mm molecular absorption line transitions in the magellanic stream

Steffes,

Rybarczyk,

Stanimirović

et al. 2024

Publ. Astron. Soc. Aust.

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The Magellanic Stream (MS), a tail of diffuse gas formed from tidal and ram pressure interactions between the Small and Large Magellanic Clouds (SMC and LMC) and the Halo of the Milky Way, is primarily composed of neutral atomic hydrogen (HI). The deficiency of dust and the diffuse nature of the present gas make molecular formation rare and difficult, but if present, could lead to regions potentially suitable for star formation, thereby allowing us to probe conditions of star formation similar to those at high redshifts. We search for $\text{HCO}^{+}$ , HCN, HNC, and C $_2$ H using the highest sensitivity observations of molecular absorption data from the Atacama Large Millimeter Array (ALMA) to trace these regions, comparing with HI archival data from the Galactic Arecibo L-Band Feed Array (GALFA) HI Survey and the Galactic All Sky Survey (GASS) to compare these environments in the MS to the HI column density threshold for molecular formation in the Milky Way. We also compare the line of sight locations with confirmed locations of stars, molecular hydrogen, and OI detections, though at higher sensitivities than the observations presented here. We find no detections to a 3 $\sigma$ significance, despite four sightlines having column densities surpassing the threshold for molecular formation in the diffuse regions of the Milky Way. Here we present our calculations for the upper limits of the column densities of each of these molecular absorption lines, ranging from $3 \times 10^{10}$ to $1 \times 10^{13}$ cm $^{-2}$ . The non-detection of $\text{HCO}^{+}$ suggests that at least one of the following is true: (i) $X_{\text{HCO}^{+}{}, \mathrm{MS}}$ is significantly lower than the Milky Way value; (ii) that the widespread diffuse molecular gas observed by Rybarczyk (2022b, ApJ, 928, 79) in the Milky Way’s diffuse interstellar medium (ISM) does not have a direct analogue in the MS; (iii) the HI-to- $\text{H}_{2}$ transition occurs in the MS at a higher surface density in the MS than in the LMC or SMC; or (iv) molecular gas exists in the MS, but only in small, dense clumps.

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DeGaS-MC: Dense Gas Survey in the Magellanic Clouds

Cited by 14 publications

References 112 publications

Dense Gas and Star Formation in Nearby Infrared Bright Galaxies: APEX survey of HCN and HCO+ J=2-1

Dense Gas and Star Formation in Nearby Infrared Bright Galaxies: APEX survey of HCN and HCO+ J=2-1

An ALMA Study of the Massive Molecular Clump N159W-North in the Large Magellanic Cloud: A Possible Gas Flow Penetrating One of the Most Massive Protocluster Systems in the Local Group

A search for 3-mm molecular absorption line transitions in the magellanic stream

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