Nonlinear hydrodynamical evolution of eccentric Keplerian discs in two dimensions: validation of secular theoryReport as inadecuate


Nonlinear hydrodynamical evolution of eccentric Keplerian discs in two dimensions: validation of secular theory


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Publication Date: 2016-03-11

Journal Title: Monthly Notices of the Royal Astronomical Society

Publisher: Oxford University Press

Language: English

Type: Article

Metadata: Show full item record

Citation: Barker, A. J., & Ogilvie, G. I. (2016). Nonlinear hydrodynamical evolution of eccentric Keplerian discs in two dimensions: validation of secular theory. Monthly Notices of the Royal Astronomical Society

Description: This is the author accepted manuscript. The final version is available from Oxford University Press via http://dx.doi.org/10.1093/mnras/stw580

Abstract: We perform global two-dimensional hydrodynamical simulations of Keplerian discs with free eccentricity over thousands of orbital periods. Our aim is to determine the validity of secular theory in describing the evolution of eccentric discs, and to explore their nonlinear evolution for moderate eccentricities. Linear secular theory is found to correctly predict the structure and precession rates of discs with small eccentricities. However, discs with larger eccentricities (and eccentricity gradients) are observed to precess faster (retrograde relative to the orbital motion), at a rate that depends on their eccentricities (and eccentricity gradients). We derive analytically a nonlinear secular theory for eccentric gas discs, which explains this result as a modification of the pressure forces whenever eccentric orbits in a disc nearly intersect. This effect could be particularly important for highly eccentric discs produced in tidal disruption events, or for narrow gaseous rings; it might also play a role in causing some of the variability in superhump binary systems. In two dimensions, the eccentricity of a moderately eccentric disc is long-lived and persists throughout the duration of our simulations. Eccentric modes are however weakly damped by their interaction with non-axisymmetric spiral density waves (driven by the Papaloizou-Pringle instability, which occurs in our idealised setup with solid walls), as well as numerical diffusion.

Keywords: accretion, accretion discs, planetary systems, hydrodynamics, waves, instabilities

Sponsorship: AJB is supported by the Leverhulme Trust and Isaac Newton Trust through the award of an Early Career Fellowship. The early stages of this research were supported by STFC through grants ST/J001570/1 and ST/L000636/1.

Identifiers:

This record's URL: http://dx.doi.org/10.1093/mnras/stw580https://www.repository.cam.ac.uk/handle/1810/254503





Author: Barker, A. J.Ogilvie, G. I.

Source: https://www.repository.cam.ac.uk/handle/1810/254503



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