English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The Velocity Gradients Technique (VGT) and the Probability Density Functions(PDFs) of mass density are tools to study turbulence, magnetic fields, andself-gravity in molecular clouds. However, self-absorption can significantlymake the observed intensity different from the column density structures. Inthis work, we study the effects of self-absorption on the VGT and the intensityPDFs utilizing three synthetic emission lines of CO isotopologs $^{12}$CO(1-0), $^{13}$CO (1-0), and C$^{18}$O (1-0). We confirm that the performance ofVGT is insensitive to the radiative transfer effect. We numerically show thepossibility of constructing 3D magnetic fields tomography through VGT. We findthat the intensity PDFs change their shape from the pure log-normal to adistribution that exhibits a power-law tail depending on the optical depth forsupersonic turbulence. We conclude the change of CO isotopologs' intensity PDFscan be independent of self-gravity, which makes the intensity PDFs lessreliable in identifying gravitational collapsing regions. We compute theintensity PDFs for a star-forming region NGC 1333 and find the change ofintensity PDFs in observation agrees with our numerical results. The synergy ofVGT and the column density PDFs confirms that the self-gravitating gas occupiesa large volume in NGC 1333.

A Synergy of the Velocity Gradients Technique and the Probability Density Functions for Identifying Gravitational Collapse in Self-Absorbing Media