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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Modern observations of the interstellar medium (ISM) in galaxies detect avariety of atomic and molecular species. The goal is to connect theseobservations to the astrochemical properties of the ISM. 3D hydro-chemicalsimulations attempt this but due to extreme computational cost, they have torely on simplified chemical networks and are bound to individual case studies.We present an alternative approach which models the ISM at larger scales by anensemble of pre-calculated 1D thermo-chemical photodissociation region (PDR)calculations that determine the abundance and excitation of atomic andmolecular species. We adopt lognormal distributions of column density (\avpdfs) for which each column density is linked to a volume density as derived byhydrodynamical simulations. We consider two lognormal {\avpdf}s: a diffuse, lowdensity medium with average visual extinction of $\overline{{\rmA}_V}=0.75\,{\rm mag}$ and dispersion of $\sigma=0.5$ and a denser giantmolecular cloud with $\overline{{\rm A}_V}=4\,{\rm mag}$ and $\sigma=0.8$. Wetreat the UV radiation field, cosmic-ray ionization rate and metallicity asfree parameters. We find that the low density medium remains fully HI- andCII-dominated under all explored conditions. The denser cloud remains almostalways molecular (i.e. H$_2$-dominated) while its carbon phase (CO, CI and CII)is sensitive to the above free parameters, implying that existing methods oftracing H$_2$-rich gas may require adjustments depending on environment. Ournumerical framework can be used to estimate the PDR properties of large ISMregions and quantify trends with different environmental parameters as it isfast, covers wide parameter space, and is flexible for extensions.

Simulating the atomic and molecular content of molecular clouds using probability distributions of physical parameters