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Paper: Molecular Photodissociation Regions in NGC 253
Volume: 320, The Neutral ISM in Starburst Galaxies
Page: 47
Authors: Paglione, T.
Abstract: We present 10.1″ × 3.5″ interferometry of CN N = 1 → 0, J = 3/2 → 1/2 emission from the starburst galaxy NGC 253. We compare high resolution maps of CN, HCN, CO and 13CO intensity to models of radiative transfer and photochemistry to infer the physical conditions of the molecular clouds in the nucleus of NGC 253. The ratio of CN and HCN intensities, which can change by orders of magnitude from cloud core to edge, is a sensitive probe of optical depth, the radiation field and photochemical processes. We also compare these data to our maps of CN, HCN and CO over the same spatial scales in the Milky Way. Our goal is to study how the global characteristics of galaxies, such as, in this case, the ambient radiation field, affect their large-scale molecular emission. The median value of I(CN)/I(HCN) in NGC 253 is ∼ 0:9, compared to the median value of ∼ 0:3 in the Galaxy. The effect of the starburst and/or the active nucleus of NGC 253 is apparent in this elevated ratio.
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