Open AccessComparison of 13 CO line and far‐infrared continuum emission as a diagnostic of dust and molecular gas physical conditions – II. The simulations: testing the method
Author(s) -
Wall W. F.
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2007.11566.x
Subject(s) - physics , astrophysics , far infrared , infrared , molecular cloud , line (geometry) , spectral line , computational physics , astronomy , stars , geometry , mathematics
The reliability of modelling the far‐infrared continuum to 13 CO J = 1 → 0 spectral line ratios applied to the Orion clouds (see previous paper in the series) on the scales of several parsecs (i.e. ∼7 pc) is tested by applying the models to simulated data. The two‐component models are found to give the dust–gas temperature difference, Δ T , to within 1 or 2 K. However, other parameters like the column density per velocity interval and the gas density can be wrong by an order of magnitude or more. In particular, the density can be systematically underestimated by an order of magnitude or more. The overall mass of the clouds is estimated correctly to within a few per cent. These results may permit us to reliably constrain estimates of the Orion clouds' physical parameters, based on the real observations of the far‐infrared continuum and 13 CO J = 1 → 0 spectral line. Nevertheless, other systematics must be treated first. These include the effects of background/foreground subtraction, effects of the H i component of the interstellar medium, and others. These will be discussed in a future paper.