The centres of M83 and the Milky Way: opposite extremes of a common star formation cycle

Author(s)
Daniel Callanan, Steven N. Longmore, J. M. Diederik Kruijssen, Andreas Schruba, Adam Ginsburg, Mark R. Krumholz, Nate Bastian, Joao Alves, Jonathan D. Henshaw, Johan H. Knapen, Melanie Chevance
Abstract

In the centres of the Milky Way and M83, the global environmental properties thought to control star formation are very similar. However, M83’s nuclear star formation rate (SFR), as estimated by synchrotron and H α emission, is an order of magnitude higher than the Milky Way’s. To understand the origin of this difference we use ALMA observations of HCN (1 − 0) and HCO+ (1 − 0) to trace the dense gas at the size scale of individual molecular clouds (0.54 arcsec, 12 pc) in the inner ∼500 pc of M83, and compare this to gas clouds at similar resolution and galactocentric radius in the Milky Way. We find that both the overall gas distribution and the properties of individual clouds are very similar in the two galaxies, and that a common mechanism may be responsible for instigating star formation in both circumnuclear rings. Given the considerable similarity in gas properties, the most likely explanation for the order of magnitude difference in SFR is time variability, with the Central Molecular Zone (CMZ) currently being at a more quiescent phase of its star formation cycle. We show M83’s SFR must have been an order of magnitude higher 5–7 Myr ago. M83’s ‘starburst’ phase was highly localized, both spatially and temporally, greatly increasing the feedback efficiency and ability to drive galactic-scale outflows. This highly dynamic nature of star formation and feedback cycles in galaxy centres means (i) modelling and interpreting observations must avoid averaging over large spatial areas or time-scales, and (ii) understanding the multiscale processes controlling these cycles requires comparing snapshots of a statistical sample of galaxies in different evolutionary stages.

Organisation(s)
Department of Astrophysics
External organisation(s)
Liverpool John Moores University (LJMU), Harvard University, Scientific Software Center, Max-Planck-Institut für extraterrestrische Physik, National Radio Astronomy Observatory, Charlottesville, Australian National University, ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Max-Planck-Institut für Astronomie, Institute of Astrophysics of the Canary Islands, University of La Laguna
Journal
Monthly Notices of the Royal Astronomical Society
Volume
505
Pages
4310–4337
No. of pages
28
ISSN
0035-8711
DOI
https://doi.org/10.1093/mnras/stab1527
Publication date
2021
Peer reviewed
Yes
Austrian Fields of Science 2012
103004 Astrophysics
Keywords
ASJC Scopus subject areas
Astronomy and Astrophysics, Space and Planetary Science
Portal url
https://ucrisportal.univie.ac.at/en/publications/f80784c3-0c29-4f21-a74a-1325185f0168