Accuracy of core mass estimates in simulated observations of dust emission

Abstract

We study the reliability of mass estimates obtained for molecular cloud cores using sub-millimetre and infrared dust emission. 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 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. Wrong assumptions of dust opacity and its spectral index beta 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 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 observations recover the true mass spectra. 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 beta whenever there are temperature variations along the line of sight. A bias can also be observed when the true beta varies with wavelength. Internal heating sources produce an inverse correlation between colour temperature and beta that may be difficult to separate from any intrinsic beta(T) relation of the dust grains. This suggests caution when interpreting the observed mass spectra and the spectral indices.

Revised version, 17 pages, 17 figures, submitted to A&A

References in corpus (13)

• Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy
• From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt survey
• The global dust SED: Tracing the nature and evolution of dust with DustEM
• The Mass Distribution and Lifetime of Prestellar Cores in Perseus, Serpens, and Ophiuchus
• Far-infrared to millimeter astrophysical dust emission I: A model based on physical properties of amorphous solids
• The Perils of Clumpfind: The Mass Spectrum of Sub-structures in Molecular Clouds
• The Power Spectrum of Supersonic Turbulence in Perseus
• The structure of molecular clouds and the universality of the clump mass function
• The dust temperatures of the prestellar cores in the rho Oph main cloud and in other star forming regions: consequences for the core mass function
• Mass and Magnetic distributions in Self Gravitating Super Alfvenic Turbulence with AMR
• Millimetre Continuum Observations of Southern Massive Star Formation Regions II. SCUBA observations of cold cores and the dust grain emissivity index $\beta$
• Measuring the Clump Mass Function in the Age of SCUBA2, Herschel, and ALMA
• Modelling Herschel observations of infrared-dark clouds in the Hi-GAL survey

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