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The life cycle of the Central Molecular Zone - II. Distribution of atomic and molecular gas tracers.

Authors
  • Armillotta, Lucia1, 2
  • Krumholz, Mark R1, 3
  • Di Teodoro, Enrico M1, 4
  • 1 Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611, Australia. , (Australia)
  • 2 Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA.
  • 3 Centre of Excellence for Astronomy in Three Dimensions (ASTRO-3D), Canberra, ACT 2611, Australia. , (Australia)
  • 4 Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA.
Type
Published Article
Journal
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press (OUP)
Publication Date
Apr 01, 2020
Volume
493
Issue
4
Pages
5273–5289
Identifiers
DOI: 10.1093/mnras/staa469
PMID: 32255842
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

We use the hydrodynamical simulation of our inner Galaxy presented in Armillotta et al. to study the gas distribution and kinematics within the Central Molecular Zone (CMZ). We use a resolution high enough to capture the gas emitting in dense molecular tracers such as NH3 and HCN, and simulate a time window of 50 Myr, long enough to capture phases during which the CMZ experiences both quiescent and intense star formation. We then post-process the simulated CMZ to calculate its spatially dependent chemical and thermal state, producing synthetic emission data cubes and maps of both H i and the molecular gas tracers CO, NH3, and HCN. We show that, as viewed from Earth, gas in the CMZ is distributed mainly in two parallel and elongated features extending from positive longitudes and velocities to negative longitudes and velocities. The molecular gas emission within these two streams is not uniform, and it is mostly associated with the region where gas flowing towards the Galactic Centre through the dust lanes collides with gas orbiting within the ring. Our simulated data cubes reproduce a number of features found in the observed CMZ. However, some discrepancies emerge when we use our results to interpret the position of individual molecular clouds. Finally, we show that, when the CMZ is near a period of intense star formation, the ring is mostly fragmented as a consequence of supernova feedback, and the bulk of the emission comes from star-forming molecular clouds. This correlation between morphology and star formation rate should be detectable in observations of extragalactic CMZs. © 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.

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