A dynamical mechanism for the origin of nuclear rings

• Verfasst von: Sormani, Mattia C. [VerfasserIn]
• Verfasst von: Sobacchi, Emanuele [VerfasserIn]
• Verfasst von: Fragkoudi, Francesca [VerfasserIn]
• Verfasst von: Ridley, Matthew [VerfasserIn]
• Verfasst von: Treß, Robin G. [VerfasserIn]
• Verfasst von: Glover, Simon [VerfasserIn]
• Verfasst von: Klessen, Ralf S. [VerfasserIn]
• Titel: A dynamical mechanism for the origin of nuclear rings
• Verf.angabe: Mattia C. Sormani, Emanuele Sobacchi, Francesca Fragkoudi, Matthew Ridley, Robin G. Tress, Simon C.O. Glover, Ralf S. Klessen
• E-Jahr: 2018
• Jahr: 14 Aug 2018
• Umfang: 19 S.
• Fussnoten: Gesehen am 30.03.2020
• Titel Quelle: Enthalten in: Royal Astronomical SocietyMonthly notices of the Royal Astronomical Society
• Ort Quelle: Oxford : Oxford Univ. Press, 1827
• Jahr Quelle: 2018
• Band/Heft Quelle: 481(2018), 1, Seite 2-19
• ISSN Quelle: 1365-2966
• DOI: doi:10.1093/mnras/sty2246
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: Astrophysics - Astrophysics of Galaxies
• K10plus-PPN: 1693463024

Abstract

We develop a dynamical theory for the origin of nuclear rings in barred galaxies. In analogy with the standard theory of accretion discs, our theory is based on shear viscous forces among nested annuli of gas. However, the fact that gas follows non circular orbits in an external barred potential has profound consequences: it creates a region of reverse shear in which it is energetically favourable to form a stable ring which does not spread despite dissipation. Our theory allows us to approximately predict the size of the ring given the underlying gravitational potential. The size of the ring is loosely related to the location of the Inner Lindblad Resonance in the epicyclic approximation, but the predicted location is more accurate and is also valid for strongly barred potentials. By comparing analytical predictions with the results of hydrodynamical simulations, we find that our theory provides a viable mechanism for ring formation if the effective sound speed of the gas is low ($\cs\lesssim1\kms$), but that nuclear spirals/shocks created by pressure destroy the ring when the sound speed is high ($\cs\simeq10\kms$). We conclude that whether this mechanism for ring formation is relevant for real galaxies ultimately depends on the effective equation of state of the ISM. Promising confirmation comes from simulations in which the ISM is modelled using state-of-the-art cooling functions coupled to live chemical networks, but more tests are needed regarding the role of turbulence driven by stellar feedback. If the mechanism is relevant in real galaxies, it could provide a powerful tool to constrain the gravitational potential, in particular the bar pattern speed.