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Verfasst von:Ossenkopf-Okada, Volker [VerfasserIn]   i
 Csengeri, T. [VerfasserIn]   i
 Schneider, N. [VerfasserIn]   i
 Federrath, C. [VerfasserIn]   i
 Klessen, Ralf S. [VerfasserIn]   i
Titel:The reliability of observational measurements of column density probability distribution functions
Verf.angabe:V. Ossenkopf-Okada, T. Csengeri, N. Schneider, C. Federrath, R.S. Klessen
E-Jahr:2016
Jahr:24 May 2016
Umfang:17 S.
Fussnoten:Gesehen am 13.10.2020
Titel Quelle:Enthalten in: Astronomy and astrophysics
Ort Quelle:Les Ulis : EDP Sciences, 1969
Jahr Quelle:2016
Band/Heft Quelle:590(2016) Artikel-Nummer A104, 17 Seiten
ISSN Quelle:1432-0746
Abstract:<i>Context. <i/>Probability distribution functions (PDFs) of column densities are an established tool to characterize the evolutionary state of interstellar clouds.<i>Aims. <i/>Using simulations, we show to what degree their determination is affected by noise, line-of-sight contamination, field selection, and the incomplete sampling in interferometric measurements.<i>Methods. <i/>We solve the integrals that describe the convolution of a cloud PDF with contaminating sources such as noise and line-of-sight emission, and study the impact of missing information on the measured column density PDF. In this way we can quantify the effect of the different processes and propose ways to correct for their impact to recover the intrinsic PDF of the observed cloud.<i>Results. <i/>The effect of observational noise can be easily estimated and corrected for if the root mean square (rms) of the noise is known. For <i>σ<i/><sub>noise<sub/> values below 40% of the typical cloud column density, <i>N<i/><sub>peak<sub/>, this involves almost no degradation in the accuracy of the PDF parameters. For higher noise levels and narrow cloud PDFs the width of the PDF becomes increasingly uncertain. A contamination by turbulent foreground or background clouds can be removed as a constant shield if the peak of the contamination PDF falls at a lower column or is narrower than that of the observed cloud. Uncertainties in cloud boundary definition mainly affect the low-column density part of the PDF and the mean density. As long as more than 50% of a cloud is covered, the impact on the PDF parameters is negligible. In contrast, the incomplete sampling of the <i>uv<i/>-plane in interferometric observations leads to uncorrectable PDF distortions in the maps produced. An extension of the capabilities of the Atacama Large Millimeter Array (ALMA) would allow us to recover the high-column density tail of the PDF, but we found no way to measure the intermediate- and low-column density part of the underlying cloud PDF in interferometric observations.
DOI:doi:10.1051/0004-6361/201628095
URL:Bitte beachten Sie: Dies ist ein Bibliographieeintrag. Ein Volltextzugriff für Mitglieder der Universität besteht hier nur, falls für die entsprechende Zeitschrift/den entsprechenden Sammelband ein Abonnement besteht oder es sich um einen OpenAccess-Titel handelt.

Volltext ; Verlag: https://doi.org/10.1051/0004-6361/201628095
 Volltext: https://www.aanda.org/articles/aa/abs/2016/06/aa28095-16/aa28095-16.html
 DOI: https://doi.org/10.1051/0004-6361/201628095
Datenträger:Online-Ressource
Sprache:eng
K10plus-PPN:1735466395
Verknüpfungen:→ Zeitschrift

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