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O’Neill, Brian C.

doi:10.1023/a:1023968127813

Cited by 77 publications

(59 citation statements)

References 15 publications

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“…Still, the evolution and the shape of the f profile are similar to those of model C (Figs 5a and d). Although resolution is an important factor in simulations aimed at exploring gravitational instabilities of thin discs embedded in large hot haloes (O'Neill & Dubinsky 2003;VK03), we find that the shape and evolution of f (R) is qualitatively the same in simulations with different resolutions.…”

Section: Bu L G E -L I K E S T Ru C T U R E F O R M At I O N a N D Romentioning

confidence: 74%

“…In the VK03 simulations of discs inside live cold dark matter (CDM) haloes, the redistribution of the angular momentum of the stellar disc is driven by the evolving bar and by interactions with the dark matter halo. This evolution produces a dense central mass concentration with nearly exponential profile, which resembles surface brightness profiles of late-type galaxy bulges (see also Athanassoula & Misiriotis 2002;O'Neill & Dubinsky 2003). Shen & Sellwood (2003) and Debattista et al (2004) argued that neither a small central mass concentration (e.g.…”

Section: Secular Bulge Formation Mechanismmentioning

confidence: 91%

“…Combes & Sanders 1981;Combes et al 1990;Pfenniger & Norman 1990;Raha et al 1991;Norman, Sellwood & Hasan 1996). However, a more recent simulations, which have many more particles and have more realistic setup, do not produce typically decaying bars (Debattista & Sellwood 2000;Athanassoula & Misiriotis 2002;O'Neill & Dubinsky 2003;Valenzuela & Klypin 2003, hereafter VK03;Shen & Sellwood 2004;Debattista et al 2004). In those simulations bars typically slightly grow over billions of years.…”

Section: Secular Bulge Formation Mechanismmentioning

confidence: 99%

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Secular evolution of galactic discs: constraints on phase-space density

Avila-Reese¹,

Carrillo²,

Valenzuela³

et al. 2005

Monthly Notices of the Royal Astronomical Society

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It was argued in the past that bulges of galaxies cannot be formed through collisionless secular evolution because that would violate constraints on the phase-space density: the phase-space density in bulges is several times larger than in the inner parts of discs. We show that these arguments against secular evolution are not correct. Observations give estimates of the coarsely grained phase-space densities of galaxies, f'=rho_s/(sigma_R sigma_phi sigma_z), where rho_s is stellar density and sigma_R, sigma_phi, sigma_z are the radial, tangential, and vertical rms velocities of stars. Using high-resolution N-body simulations, we study the evolution of f' in discs of Galaxy-size models. During the secular evolution, the discs, which are embedded in live CDM haloes, form a bar and then a thick, dynamically hot, central mass concentration. In the course of evolution f' declines at all radii, not just in the central region. However, the decline is different in different parts of the disc. In the inner disc, f'(R) develops a valley with a minimum around the end of the central mass concentration. The final result is that the values of f' in the central regions are significantly larger than those in the inner disc. The minimum, which gets deeper with time, seems to be due to a large phase mixing produced by the outer bar. We find that the shape and the amplitude of f'(R) for different simulations agree qualitatively with the observed f'(R) in our Galaxy. Curiously enough, the fact that the coarsely grained phase-space density of the bulge is significantly larger than the one of the inner disc turns out to be an argument in favor of secular formation of bulges, not against it.Comment: 9 pages, 5 figures included. Accepted for publication in MNRAS. Minor changes after referee's report. Two figures added (possition-velocity diagrams) to show (i) the agreement in the mass distribution of one of our models with that of the Galaxy, and (ii) the (minor) influence of gas on this distributio

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Section: Bu L G E -L I K E S T Ru C T U R E F O R M At I O N a N D Romentioning

confidence: 74%

Section: Secular Bulge Formation Mechanismmentioning

confidence: 91%

Section: Secular Bulge Formation Mechanismmentioning

confidence: 99%

See 1 more Smart Citation

Secular evolution of galactic discs: constraints on phase-space density

Avila-Reese¹,

Carrillo²,

Valenzuela³

et al. 2005

Monthly Notices of the Royal Astronomical Society

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“…There is, however, considerable angular momentum exchange between the disc and the halo component, as in models with axisymmetric haloes (e.g. Sellwood 1980;Debattista & Sellwood 2000;Athanassoula 2003;O'Neill & Dubinski 2003;Martinez-Valpuesta, Shlosman & Hellar;2006;Villa-Vargas, Sholsman & Hellar;). The net amount of angular momentum lost by the disc is gained by the halo in all models.…”

Section: Standard Models and Models With Initially Circular Discsmentioning

confidence: 99%

Loss of halo triaxiality due to bar formation

Machado

Athanassoula

2010

Monthly Notices of the Royal Astronomical Society

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Cosmological N-body simulations indicate that the dark matter haloes of galaxies should be generally triaxial. Yet, the presence of a baryonic disc is believed to alter the shape of the haloes. Here we aim to study how bar formation is affected by halo triaxiality and how, in turn, the presence of the bar influences the shape of the halo. We perform a set of collisionless N-body simulations of disc galaxies with triaxial dark matter haloes, using elliptical discs as initial conditions. We study models of different halo triaxialities and, to investigate the behaviour of the halo shape in the absence of bar formation, we run models with different disc masses, halo concentrations, disc velocity dispersions and also models where the disc shape is kept artificially axisymmetric. We find that the introduction of a massive disc causes the halo triaxiality to be partially diluted. Once the disc is fully grown, a strong stellar bar develops within the halo that is still non-axisymmetric, causing it to lose its remaining non-axisymmetry. In triaxial haloes in which the initial conditions are such that a bar does not form, the halo is able to remain triaxial and the circularisation of its shape on the plane of the disc is limited to the period of disc growth. We conclude that part of the circularisation of the halo is due to disc growth, but part must be attributed to the formation of a bar. We find that initially circular discs respond excessively to the triaxial potential and become highly elongated. They also lose more angular momentum than the initially elliptical discs and thus form stronger bars. Because of that, the circularisation that their bars induce on their haloes is also more rapid. We also analyse halo vertical shapes and observe that their vertical flattenings remain considerable, meaning that the haloes become approximately oblate by the end of the simulations. [abridged]Comment: 20 pages, 26 figures, accepted for publication in MNRA

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“…Jogee, Scoville & Kenney 2005;Sheth et al 2005; Barazza, Jogee & Marinova 2008;Sheth et al 2008;Aguerri, Méndez-Abreu & Corsini 2009;Cameron et al 2010;Nair & Abraham 2010;Ellison et al 2011;Hoyle et al 2011;Masters et al 2011) and have been modelled with detailed numerical simulations, including their interactions with the host dark matter haloes (e.g. Valenzuela & Klypin 2003;O'Neill & Dubinski 2003;Debattista et al 2006;Heller, Shlosman & Athanassoula 2007;Weinberg & Katz 2007).…”

Section: Introductionmentioning

confidence: 99%

Galaxy Zoo: the environmental dependence of bars and bulges in disc galaxies

Skibba

Masters

Nichol

et al. 2012

Monthly Notices of the Royal Astronomical Society

120

123

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We present an analysis of the environmental dependence of bars and bulges in disc galaxies, using a volume‐limited catalogue of 15 810 galaxies at z < 0.06 from the Sloan Digital Sky Survey with visual morphologies from the Galaxy Zoo 2 project. We find that the likelihood of having a bar, or bulge, in disc galaxies increases when the galaxies have redder (optical) colours and larger stellar masses, and observe a transition in the bar and bulge likelihoods at M*= 2 × 1010 M⊙, such that massive disc galaxies are more likely to host bars and bulges. In addition, while some barred and most bulge‐dominated galaxies are on the ‘red sequence’ of the colour–magnitude diagram, we see a wider variety of colours for galaxies that host bars. We use galaxy clustering methods to demonstrate statistically significant environmental correlations of barred, and bulge‐dominated, galaxies, from projected separations of 150 kpc h−1 to 3 Mpc h−1. These environmental correlations appear to be independent of each other: i.e. bulge‐dominated disc galaxies exhibit a significant bar–environment correlation, and barred disc galaxies show a bulge–environment correlation. As a result of sparse sampling tests – our sample is nearly 20 times larger than those used previously – we argue that previous studies that did not detect a bar–environment correlation were likely inhibited by small number statistics. We demonstrate that approximately half of the bar–environment correlation can be explained by the fact that more massive dark matter haloes host redder disc galaxies, which are then more likely to have bars; this fraction is estimated to be 50 ± 10 per cent from a mock catalogue analysis and 60 ± 5 per cent from the data. Likewise, we show that the environmental dependence of stellar mass can only explain a smaller fraction (25 ± 10 per cent) of the bar–environment correlation. Therefore, a significant fraction of our observed environmental dependence of barred galaxies is not due to colour or stellar mass dependences, and hence must be due to another galaxy property, such as gas content, or to environmental influences. Finally, by analysing the projected clustering of barred and unbarred disc galaxies with halo occupation models, we argue that barred galaxies are in slightly higher mass haloes than unbarred ones, and some of them (approximately 25 per cent) are satellite galaxies in groups. We discuss the implications of our results on the effects of minor mergers and interactions on bar formation in disc galaxies.

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Untitled

Cited by 77 publications

References 15 publications

Secular evolution of galactic discs: constraints on phase-space density

Secular evolution of galactic discs: constraints on phase-space density

Loss of halo triaxiality due to bar formation

Galaxy Zoo: the environmental dependence of bars and bulges in disc galaxies

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