MEASURING THE CLUMP MASS FUNCTION IN THE AGE OF SCUBA2,<i>HERSCHEL</i>, AND ALMA

Reid, Michael A.; Wadsley, James; Petitclerc, Nicolas; Sills, Alison

doi:10.1088/0004-637x/719/1/561

Cited by 39 publications

(54 citation statements)

References 33 publications

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“…Stutzki & Güsten 1990;Heithausen et al 1998;Kramer et al 1998;Reid et al 2010;Veltchev, Donkov & Klessen 2013 Fig. 7, right; shaded area denotes its uncertainty due to uncertainty of α vir (cf.…”

Section: Clump Mass Functionsmentioning

confidence: 99%

Spatially associated clump populations in Rosette from CO and dust maps

Veltchev

Ossenkopf-Okada

Stanchev

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Spatial association of clumps from different tracers turns out to be a valuable tool to determine the physical properties of molecular clouds. It provides a reliable estimate for the X-factors, serves to trace the density of clumps seen in column densities only and allows to measure the velocity dispersion of clumps identified in dust emission. We study the spatial association between clump populations, extracted by use of the Gaussclumps technique from 12 CO (1 − 0), 13 CO (1 − 0) line maps and Herschel dust-emission maps of the star-forming region Rosette, and analyse their physical properties. All CO clumps that overlap with another CO or dust counterpart are found to be gravitationally bound and located in the massive star-forming filaments of the molecular cloud. They obey a single mass-size relation M cl ∝ R γ cl with γ ≃ 3 (implying constant mean density) and display virtually no velocity-size relation. We interpret their population as low-density structures formed through compression by converging flows and still not evolved under the influence of self-gravity. The high-mass parts of their clump mass functions are fitted by a power law dN cl /d log M cl ∝ M Γ cl and display a nearly Salpeter slope Γ ∼ −1.3. On the other hand, clumps extracted from the dust-emission map exhibit a shallower mass-size relation with γ = 2.5 and mass functions with very steep slopes Γ ∼ −2.3 even if associated with CO clumps. They trace density peaks of the associated CO clumps at scales of a few tenths of pc where no single density scaling law should be expected.

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Section: Clump Mass Functionsmentioning

confidence: 99%

Spatially associated clump populations in Rosette from CO and dust maps

Veltchev

Ossenkopf-Okada

Stanchev

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Contours in steps of the noise level are less biased and would generate more substructure, hence clumps. However, noise would, more likely, generate artificial clumps as studied by Reid et al (2010). The chosen peak flux threshold of 0.5 Jy/beam corresponds to 1 × 10 23 cm −2 .…”

Section: Atlasgal and Clump Finding Limitationsmentioning

confidence: 99%

Search for starless clumps in the ATLASGAL survey

Tackenberg

Beuther

Henning

et al. 2012

A&A

100

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Context. Understanding massive star formation requires comprehensive knowledge about the initial conditions of this process. The cradles of massive stars are believed to be located in dense and massive molecular clumps. Aims. In this study, we present an unbiased sample of the earliest stages of massive star formation across 20 deg 2 of the sky. Methods. Within the region 10 • < l < 20 • and |b| < 1 • , we search the ATLASGAL survey at 870 μm for dense gas condensations. These clumps are carefully examined for indications of ongoing star formation using YSOs from the GLIMPSE source catalog as well as sources in the 24 μm MIPSGAL images, to search for starless clumps. We calculate the column densities as well as the kinematic distances and masses for sources where the v lsr is known from spectroscopic observations. Results. Within the given region, we identify 210 starless clumps with peak column densities >1 × 10 23 cm −2 . In particular, we identify potential starless clumps on the other side of the Galaxy. The sizes of the clumps range between 0.1 pc and 3 pc with masses between a few tens of M up to several ten thousands of M . Most of them may form massive stars, but in the 20 deg 2 area we only find 14 regions massive enough to form stars more massive than 20 M and 3 regions with the potential to form stars more massive than 40 M . The slope of the high-mass tail of the clump mass function for clumps on the near side of the Galaxy is α = 2.2 and, therefore, Salpeter-like. We estimate the lifetime of the most massive starless clumps to be (6 ± 5) × 10 4 yr. Conclusions. The sample offers a uniform selection of starless clumps. In the large area surveyed, we only find a few potential precursors of stars in the excess of 40 M . It appears that the lifetime of these clumps is somewhat shorter than their free-fall times, although both values agree within the errors. In addition, these are ideal objects for detailed studies and follow-up observations.

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“…Also the used algorithms and their parameter values, or image acquisition techniques, can affect the derived CMF (e.g. Smith et al 2008;Pineda et al 2009;Reid et al 2010). …”

Section: Introductionmentioning

confidence: 99%

Accuracy of core mass estimates in simulated observations of dust emission

Malinen

Juvela

Collins

et al. 2011

A&A

152

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Aims. We study the reliability of the mass estimates obtained for molecular cloud cores using sub-millimetre and infrared dust emission. Methods. We use magnetohydrodynamic simulations and radiative transfer to produce synthetic observations with spatial resolution and noise levels typical of Herschel surveys. We estimate dust colour temperatures using different pairs of intensities, calculate column densities with opacity at one wavelength, and compare the estimated masses with the true values. We compare these results to the case when all five Herschel wavelengths are available. We investigate the effects of spatial variations of dust properties and the influence of embedded heating sources. Results. Wrong assumptions of dust opacity and its spectral index β can cause significant systematic errors in mass estimates. These are mainly multiplicative and leave the slope of the mass spectrum intact, unless cores with very high optical depth are included. Temperature variations bias the colour temperature estimates and, in quiescent cores with optical depths higher than for normal stable cores, masses can be underestimated by up to one order of magnitude. When heated by internal radiation sources, the dust in the core centre becomes visible and the observations recover the true mass spectra. Conclusions. The shape, although not the position, of the mass spectrum is reliable against observational errors and biases introduced in the analysis. This changes only if the cores have optical depths much higher than expected for basic hydrostatic equilibrium conditions. Observations underestimate the value of β whenever there are temperature variations along the line of sight. A bias can also be observed when the true β varies with wavelength. Internal heating sources produce an inverse correlation between colour temperature and β that may be difficult to separate from any intrinsic β(T ) relation of the dust grains. This suggests caution when interpreting the observed mass spectra and the spectral indices.

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MEASURING THE CLUMP MASS FUNCTION IN THE AGE OF SCUBA2,HERSCHEL, AND ALMA

Cited by 39 publications

References 33 publications

Spatially associated clump populations in Rosette from CO and dust maps

Spatially associated clump populations in Rosette from CO and dust maps

Search for starless clumps in the ATLASGAL survey

Accuracy of core mass estimates in simulated observations of dust emission

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