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/

Zendy Plus

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

Zendy Tools

Zendy Open

CO observations have been so far the best way to trace molecular gas inexternal galaxies, but at low metallicity the gas mass deduced could be largelyunderestimated. At present, the kinematic information of CO data cubes are usedto estimate virial masses and trace the total mass of the molecular clouds.Millimeter dust emission can also be used as a dense gas tracer and couldunveil H2 envelopes lacking CO. These different tracers must be compared indifferent environments. This study compares virial masses to masses deducedfrom millimeter emission, in two GMC samples: the local molecular clouds in ourGalaxy and their equivalents in the Small Magellanic Cloud (SMC), one of thenearest low metallicity dwarf galaxy. In our Galaxy, mass estimates deducedfrom millimeter emission are consistent with masses deduced from gamma rayanalysis and trace the total mass of the clouds. Virial masses aresystematically larger (twice on average) than mass estimates from millimeterdust emission. This difference decreases toward high masses and has alreadybeen reported in previous studies. In the SMC however, molecular cloud massesdeduced from SIMBA millimeter observations are systematically higher (twice onaverage for conservative values of the dust to gas ratio and dust emissivity)than the virial masses from SEST CO observations. The observed excess can notbe accounted for by any plausible change of dust properties. Taking a generalform for the virial theorem, we show that a magnetic field strength of ~15micro Gauss in SMC clouds could provide additional support to the clouds andexplain the difference observed. Masses of SMC molecular clouds have thereforebeen underestimated so far. Magnetic pressure may contribute significantly totheir support.

Millimeter dust continuum emission unveiling the true mass of giant molecular clouds in the Small Magellanic Cloud