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dc.contributor.authorPatra, Narendra Nath-
dc.identifier.citationAstronomy & Astrophysics, 2020, Vol.638, Article No. A66en_US
dc.identifier.issn1432-0746 (Online)-
dc.descriptionOpen Accessen_US
dc.description.abstractAs recent observations of the molecular discs in spiral galaxies point to the existence of a diffuse, low-density thick molecular disc along with the prominent thin one, we investigate the observational signatures of this thick disc by theoretically modelling two-component molecular discs in a sample of eight nearby spiral galaxies. Assuming a prevailing hydrostatic equilibrium, we set up and solved the joint Poisson’s-Boltzmann equation to estimate the three-dimensional distribution of the molecular gas and the molecular scale height in our sample galaxies. The molecular scale height in a two-component molecular disc is found to vary between 50 and 300 pc, which is higher than what is found in a single-component disc. We find that this scale height can vary significantly depending on the assumed thick disc molecular gas fraction. We also find that the molecular gas flares as a function of the radius and follows a tight exponential law with a scale length of (0.48 ± 0.01)r25. We used the density solutions to produce the column density maps and spectral cubes to examine the ideal observing conditions to identify a thick molecular disc in galaxies. We find that unless the molecular disc is an edge-on system and imaged with a high spatial resolution (≲100 pc), it is extremely hard to identify a thick molecular disc in a column density map. The spectral analysis further reveals that at moderate to high inclination (i ≳ 40°), spectral broadening can fictitiously introduce the signatures of a two-component disc into the spectral cube of a single-component disc. Hence, we conclude that a low inclination molecular disc imaged with high spatial resolution would serve as the ideal site for identifying the thick molecular disc in galaxies.en_US
dc.publisherEDP Sciences for European Southern Observatoryen_US
dc.rights2020 European Southern Observatoryen_US
dc.subjectmolecular dataen_US
dc.subjectISM: moleculesen_US
dc.subjectgalaxies: kinematics and dynamicsen_US
dc.subjectgalaxies: spiralen_US
dc.subjectgalaxies: structureen_US
dc.titleTheoretical modelling of two-component molecular discs in spiral galaxiesen_US
Appears in Collections:Research Papers (A&A)

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