Rigby, A.J. orcid.org/0000-0002-3351-2200, Thompson, M.A. orcid.org/0000-0001-5392-909X, Eden, D.J. et al. (7 more authors) (2025) PAMS: The Perseus Arm Molecular Survey–I. Survey description and first results. Monthly Notices of the Royal Astronomical Society, 538 (1). pp. 198-222. ISSN 0035-8711
Abstract
The external environments surrounding molecular clouds vary widely across galaxies such as the Milky Way, and statistical samples of clouds are required to understand them. We present the Perseus Arm Molecular Survey (PAMS), a James Clerk Maxwell Telescope (JCMT) survey combining new and archival data of molecular-cloud complexes in the outer Perseus spiral arm in 12CO, 13CO, and C18O (J = 3–2). With a survey area of ∼8 deg2, PAMS covers well-known complexes such as W3, W5, and NGC 7538 with two fields at ≈ 110◦ and ≈ 135◦. PAMS has an effective resolution of 17 arcsec, and rms sensitivity of Tmb = 0.7–1.0 K in 0.3 km s−1 channels. Here we present a first look at the data, and compare the PAMS regions in the Outer Galaxy with Inner Galaxy regions from the CO Heterodyne Inner Milky Way Plane Survey (CHIMPS). By comparing the various CO data with maps of H2 column density from Herschel, we calculate representative values for the CO-to-H2 column-density X-factors, which are X12CO (3−2) = 4.0 × 1020 and X13CO (3−2) = 4.0 × 1021 cm−2 (K km s−1) −1 with a factor of 1.5 uncertainty. We find that the emission profiles, size–linewidth, and mass–radius relationships of 13CO-traced structures are similar between the Inner and Outer Galaxy. Although PAMS sources are slightly more massive than their Inner Galaxy counterparts for a given size scale, the discrepancy can be accounted for by the Galactic gradient in gas-to-dust mass ratio, uncertainties in the X-factors, and selection biases. We have made the PAMS data publicly available, complementing other CO surveys targeting different regions of the Galaxy in different isotopologues and transitions.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2025 The Author(s). This is an open access article under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. |
Keywords: | molecular data, surveys, stars: formation, ISM: clouds, galaxies: ISM, submillimetre: ISM |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 21 Mar 2025 08:56 |
Last Modified: | 21 Mar 2025 08:56 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/mnras/staf278 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:224681 |