University of Hertfordshire

From the same journal

From the same journal

By the same authors

Documents

  • J-AAM-III

    Accepted author manuscript, 8 MB, PDF document

View graph of relations
Original languageEnglish
Pages (from-to)3307–3326
JournalMonthly Notices of the Royal Astronomical Society
Journal publication date2 Apr 2019
Volume486
Issue3
Early online date2 Apr 2019
DOIs
Publication statusE-pub ahead of print - 2 Apr 2019

Abstract

As part of a series of papers aimed at understanding the evolution of the Milky Way's Central Molecular Zone (CMZ), we present hydrodynamical simulations of turbulent molecular clouds orbiting in an accurate model of the gravitational potential extant there. We consider two sets of model clouds differing in the energy content of their velocity fields. In the first, self--virialised set, the turbulent kinetic energies are chosen to be close in magnitude to the clouds' self--gravitational potential energies. Comparison with isolated clouds evolving without an external potential shows that the self--virialised clouds are unable to withstand the compressive tidal field of the CMZ and rapidly collapse, forming stars much faster and reaching gas exhaustion after a small fraction of a Galactocentric orbit. In the second, tidally--virialised, set of simulations, the clouds' turbulent kinetic energies are in equilibrium with the external tidal field. These models are better supported against the field and the stronger turbulence suppresses star formation. Our results strongly support the inference that anomalously low star formation rates in the CMZ are due primarily to high velocity dispersions in the molecular gas. The clouds follow open, eccentric orbits oscillating in all three spatial coordinates. We examine the consequences of the orbital dynamics, particularly pericentre passage, by performing companion simulations of clouds on circular orbits. The increased tidal forces at pericentre produce transient accelerations in star formation rates of at most a factor of 2.7. Our results demonstrate that modelling star formation in galactic centres requires the inclusion of tidal forces.

Notes

© 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.

ID: 16711252