‘The Brick’ is not a brick: a comprehensive study of the structure and dynamics of the central molecular zone cloud G0.253+0.016
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Issue Date
2019-02-17Author
Henshaw, J.D.
Ginsburg, A.
Haworth, T.J.
Longmore, S.N.
Kruijssen, J.M.D.
Mills, Elisabeth
Sokolov, V.
Walker, D.L.
Barnes, A.T.
Contreras, Y.
Bally, J.
Battersby, C.
Beuther, H.
Butterfield, N.
Dale, J.E.
Henning, T.
Jackson, J.M.
Kauffmann, J.
Pillai, T.
Ragan, S.
Riener, M.
Zhang, Q.
Publisher
Royal Astronomical Society
Type
Article
Article Version
Scholarly/refereed, publisher version
Rights
© 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.
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Show full item recordAbstract
In this paper we provide a comprehensive description of the internal dynamics of G0.253+0.016 (a.k.a. ‘the Brick’); one of the most massive and dense molecular clouds in the Galaxy to lack signatures of widespread star formation. As a potential host to a future generation of high-mass stars, understanding largely quiescent molecular clouds like G0.253+0.016 is of critical importance. In this paper, we reanalyse Atacama Large Millimeter Array cycle 0 HNCO J = 4(0, 4) − 3(0, 3) data at 3 mm, using two new pieces of software that we make available to the community. First, SCOUSEPY, a Python implementation of the spectral line fitting algorithm SCOUSE. Secondly, ACORNS (Agglomerative Clustering for ORganising Nested Structures), a hierarchical n-dimensional clustering algorithm designed for use with discrete spectroscopic data. Together, these tools provide an unbiased measurement of the line-of-sight velocity dispersion in this cloud, σvlos,1D=4.4±2.1 km s−1, which is somewhat larger than predicted by velocity dispersion-size relations for the central molecular zone (CMZ). The dispersion of centroid velocities in the plane of the sky are comparable, yielding σvlos,1D/σvpos,1D∼1.2±0.3. This isotropy may indicate that the line-of-sight extent of the cloud is approximately equivalent to that in the plane of the sky. Combining our kinematic decomposition with radiative transfer modelling, we conclude that G0.253+0.016 is not a single, coherent, and centrally condensed molecular cloud; ‘the Brick’ is not a brick. Instead, G0.253+0.016 is a dynamically complex and hierarchically structured molecular cloud whose morphology is consistent with the influence of the orbital dynamics and shear in the CMZ.
Description
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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Citation
J D Henshaw, A Ginsburg, T J Haworth, S N Longmore, J M D Kruijssen, E A C Mills, V Sokolov, D L Walker, A T Barnes, Y Contreras, J Bally, C Battersby, H Beuther, N Butterfield, J E Dale, T Henning, J M Jackson, J Kauffmann, T Pillai, S Ragan, M Riener, Q Zhang, ‘The Brick’ is not a brick: a comprehensive study of the structure and dynamics of the central molecular zone cloud G0.253+0.016, Monthly Notices of the Royal Astronomical Society, Volume 485, Issue 2, May 2019, Pages 2457–2485, https://doi.org/10.1093/mnras/stz471
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