LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud

Bot, Caroline; Rubio, M.; Boulanger, F.; Albrecht, M.; Leroy, Adam K.; Bolatto, Alberto D.; Bertoldi, F.; Gordon, K. D.; Engelbracht, C. W.; Block, M.; Misselt, K. A.

doi:10.1051/0004-6361/200913372

Cited by 33 publications

(45 citation statements)

References 42 publications

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“…Both Sk13 and Sk18 are located in the N19 complex of H II regions, supernova remnants, and molecular gas in the southwest part of the main SMC "bar," near DEM31 and DEM32, respectively (Rubio et al 1993a;Rosado et al 1994;Dickel et al 2001;Bot et al 2010). The sight line to Sk13 exhibits "typical" SMC extinction, with no 2175Å bump and a very steep far-UV rise (Gordon et al 2003).…”

Section: Sight Linesmentioning

confidence: 99%

Thermal Pressures in the Interstellar Medium of the Magellanic Clouds*

Welty

Lauroesch

Wong

et al. 2016

ApJ

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We discuss the thermal pressures (n H T) in predominantly cold, neutral interstellar gas in the Magellanic Clouds, derived from analyses of the fine-structure excitation of neutral carbon, as seen in high-resolution Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra of seven diverse sight lines in the LMC and SMC. Detailed fits to the line profiles of the absorption from C I, C I * , and C I ** yield consistent column densities for the three to six C I multiplets detected in each sight line. In the LMC and SMC, N(C I tot ) is consistent with Galactic trends versus N(Na I) and N(CH), but is slightly lower versus N(K I) and N(H 2 ). As for N(Na I) and N(K I), N(C I tot ) is generally significantly lower, for a given N(H tot ), in the LMC and (especially) in the SMC, compared to the local Galactic relationship. For the LMC and SMC components with well-determined column densities for C I, C I * , and C I ** , the derived thermal pressures are typically factors of a few higher than the values found for most cold, neutral clouds in the Galactic ISM. Such differences are consistent with the predictions of models for clouds in systems (like the LMC and SMC) that are characterized by lower metallicities, lower dust-to-gas ratios, and enhanced radiation fields-where higher pressures are required for stable cold, neutral clouds. The pressures may be further enhanced by energetic activity (e.g., due to stellar winds, star formation, and/or supernova remnants) in several of the regions probed by these sight lines. Comparisons are made with the C I observed in some quasar absorption-line systems.

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Section: Sight Linesmentioning

confidence: 99%

Thermal Pressures in the Interstellar Medium of the Magellanic Clouds*

Welty

Lauroesch

Wong

et al. 2016

ApJ

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“…Submillimeter observations have become an important tool for investigating these dense cloud structures. LABOCA has already been used for surveys of A&A 550, A29 (2013) distant molecular clouds and clumps (Schuller et al 2009;Bot et al 2010).…”

Section: Introductionmentioning

confidence: 99%

The clump mass function of the dense clouds in the Carina nebula complex

Pekruhl

Preibisch

Schüller

et al. 2013

A&A

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Context. The question how the initial conditions in a star-forming region affect the resulting mass function of the forming stars is one of the most fundamental open topics in star formation theory. Aims. We want to characterize the properties of the cold dust clumps in the Carina nebula complex, which is one of the most massive star forming regions in our Galaxy and shows a very high level of massive star feedback. We derive the clump mass function (ClMF), explore the reliability of different clump extraction algorithms, and investigate the influence of the temperatures within the clouds on the resulting shape of the ClMF. Methods. We analyze a 1.25 • × 1.25 • wide-field submillimeter map obtained with LABOCA at the APEX telescope, which provides the first spatially complete survey of the clouds in the Carina nebula complex. We use the three clump-finding algorithms CLUMPFIND, GAUSSCLUMPS and SExtractor to identify individual clumps and determine their total fluxes. In addition to assuming a common "typical" temperature for all clouds, we also employ an empirical relation between cloud column densities and temperature to determine an estimate of the individual clump temperatures, and use this to determine individual clump masses. Results. We find that the ClMFs resulting from the different extraction methods show considerable differences in their shape. While the ClMF based on the CLUMPFIND extraction is very well described by a power-law (for clump masses well above the completeness limit), the ClMFs based on the extractions with GAUSSCLUMPS and SExtractor are better represented by a log-normal distribution. We also find that the use of individual clump temperatures leads to a shallower ClMF slope than the (often used) assumption of a common temperature (e.g. 20 K) of all clumps. Conclusions. The power-law of dN/dM ∝ M −1.95 we find for the CLUMPFIND sample is in good agreement with ClMF slopes found in previous studies of the ClMFs of other regions. The dependence of the ClMF shape (power-law versus log-normal distribution) on the employed extraction method suggests that observational determinations of the ClMF shape yields only very limited information about the true structure of the cloud. Interpretations of log-normal ClMF shape as a signature of turbulent pre-stellar clouds versus power-law ClMFs as a signature of star-forming clouds may be taken with caution for a single extraction algorithm without additional information.

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“…The presence of a hidden gas mass in low metallicity galaxies is also suggested by dust observations of the Magellanic Clouds (e.g. Bernard et al 2008;Dobashi et al 2008;Leroy et al 2007;Roman-Duval et al 2010;Bot et al 2010a). …”

Section: Introductionmentioning

confidence: 64%

Planckearly results. XVII. Origin of the submillimetre excess dust emission in the Magellanic Clouds

Ade¹,

Aghanim²,

Arnaud³

et al. 2011

A&A

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125

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The integrated spectral energy distributions (SED) of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) appear significantly flatter than expected from dust models based on their far-infrared and radio emission. The still unexplained origin of this millimetre excess is investigated here using the Planck data. The integrated SED of the two galaxies before subtraction of the foreground (Milky Way) and background (CMB fluctuations) emission are in good agreement with previous determinations, confirming the presence of the millimetre excess. In the context of this preliminary analysis we do not propose a full multi-component fitting of the data, but instead subtract contributions unrelated to the galaxies and to dust emission. The background CMB contribution is subtracted using an internal linear combination (ILC) method performed locally around the galaxies. The foreground emission from the Milky Way is subtracted as a Galactic H i template, and the dust emissivity is derived in a region surrounding the two galaxies and dominated by Milky Way emission. After subtraction, the remaining emission of both galaxies correlates closely with the atomic and molecular gas emission of the LMC and SMC. The millimetre excess in the LMC can be explained by CMB fluctuations, but a significant excess is still present in the SMC SED. The Planck and IRAS-IRIS data at 100 μm are combined to produce thermal dust temperature and optical depth maps of the two galaxies.Corresponding author: J.-P. Bernard, e-mail: jean-philippe.bernard@cesr.frArticle published by EDP Sciences A17, page 1 of 17 A&A 536, A17 (2011) The LMC temperature map shows the presence of a warm inner arm already found with the Spitzer data, but which also shows the existence of a previously unidentified cold outer arm. Several cold regions are found along this arm, some of which are associated with known molecular clouds. The dust optical depth maps are used to constrain the thermal dust emissivity power-law index (β). The average spectral index is found to be consistent with β =1.5 and β =1.2 below 500 μm for the LMC and SMC respectively, significantly flatter than the values observed in the Milky Way. Also, there is evidence in the SMC of a further flattening of the SED in the sub-mm, unlike for the LMC where the SED remains consistent with β =1.5. The spatial distribution of the millimetre dust excess in the SMC follows the gas and thermal dust distribution. Different models are explored in order to fit the dust emission in the SMC. It is concluded that the millimetre excess is unlikely to be caused by very cold dust emission and that it could be due to a combination of spinning dust emission and thermal dust emission by more amorphous dust grains than those present in our Galaxy.

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LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud

Cited by 33 publications

References 42 publications

Thermal Pressures in the Interstellar Medium of the Magellanic Clouds*

Thermal Pressures in the Interstellar Medium of the Magellanic Clouds*

The clump mass function of the dense clouds in the Carina nebula complex

Planckearly results. XVII. Origin of the submillimetre excess dust emission in the Magellanic Clouds

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