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Title: Models of bars − II. Exponential profiles

Abstract

ABSTRACT We present a new model for galactic bars with exponentially falling major axis luminosity profiles and Gaussian cross-sections. This is based on the linear superposition of Gaussian potential–density pairs with an exponential weight function, using an extension of the method originally introduced by Long & Murali. We compute the density, potential, and forces, using Gaussian quadrature. These quantities are given as explicit functions of position. There are three independent scaled bar parameters that can be varied continuously to produce bespoke bars of a given mass and shape. We categorize the effective potential by splitting a reduced parameter space into six regions. Unusually, we find bars with three stable Lagrange points on the major axis are possible. Our model reveals a variety of unexpected orbital structure, including a bifurcating x1 orbit coexisting with a stable x4 orbit. Propeller orbits are found to play a dominant role in the orbital structure, and we find striking similarities between our bar configuration and the model of Kaufmann & Contopoulos. We find a candidate orbital family, sired from the propeller orbits, that may be responsible for the observed high-velocity peaks in the Milky Way’s bar. As a cross-check, we inspect, for the first time, the propermore » motions of stars in the high-velocity peaks, which also match our suggested orbital family well. This work adds to the increasing body of evidence that real galactic bars may be supported at least partly by propeller orbits rather than solely by elliptical-like orbits of the x1 family.« less

Authors:
 [1];  [1]; ORCiD logo [1]
  1. Institute of Astronomy, Madingley Road, Cambridge CB3 0HH, UK
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1603185
Resource Type:
Published Article
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Name: Monthly Notices of the Royal Astronomical Society Journal Volume: 493 Journal Issue: 2; Journal ID: ISSN 0035-8711
Publisher:
Oxford University Press
Country of Publication:
United Kingdom
Language:
English

Citation Formats

McGough, D. P., Evans, N. W., and Sanders, J. L. Models of bars − II. Exponential profiles. United Kingdom: N. p., 2020. Web. doi:10.1093/mnras/staa491.
McGough, D. P., Evans, N. W., & Sanders, J. L. Models of bars − II. Exponential profiles. United Kingdom. doi:10.1093/mnras/staa491.
McGough, D. P., Evans, N. W., and Sanders, J. L. Tue . "Models of bars − II. Exponential profiles". United Kingdom. doi:10.1093/mnras/staa491.
@article{osti_1603185,
title = {Models of bars − II. Exponential profiles},
author = {McGough, D. P. and Evans, N. W. and Sanders, J. L.},
abstractNote = {ABSTRACT We present a new model for galactic bars with exponentially falling major axis luminosity profiles and Gaussian cross-sections. This is based on the linear superposition of Gaussian potential–density pairs with an exponential weight function, using an extension of the method originally introduced by Long & Murali. We compute the density, potential, and forces, using Gaussian quadrature. These quantities are given as explicit functions of position. There are three independent scaled bar parameters that can be varied continuously to produce bespoke bars of a given mass and shape. We categorize the effective potential by splitting a reduced parameter space into six regions. Unusually, we find bars with three stable Lagrange points on the major axis are possible. Our model reveals a variety of unexpected orbital structure, including a bifurcating x1 orbit coexisting with a stable x4 orbit. Propeller orbits are found to play a dominant role in the orbital structure, and we find striking similarities between our bar configuration and the model of Kaufmann & Contopoulos. We find a candidate orbital family, sired from the propeller orbits, that may be responsible for the observed high-velocity peaks in the Milky Way’s bar. As a cross-check, we inspect, for the first time, the proper motions of stars in the high-velocity peaks, which also match our suggested orbital family well. This work adds to the increasing body of evidence that real galactic bars may be supported at least partly by propeller orbits rather than solely by elliptical-like orbits of the x1 family.},
doi = {10.1093/mnras/staa491},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 2,
volume = 493,
place = {United Kingdom},
year = {2020},
month = {2}
}

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DOI: 10.1093/mnras/staa491

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