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Using $N$-body simulations we study the buckling instability in a galactic bar forming in a Milky Way-like galaxy. The galaxy is initially composed of an axisymmetric, exponential stellar disk embedded in a spherical dark matter halo. The…

Astrophysics of Galaxies · Physics 2019-09-04 Ewa L. Lokas

Strong galactic bars produced in simulations tend to undergo a period of buckling instability that weakens and thickens them and forms a boxy/peanut structure in their central parts. This theoretical prediction has been confirmed by…

Astrophysics of Galaxies · Physics 2019-04-03 Ewa L. Lokas

Young stellar bars in disk galaxies experience a vertical buckling instability which terminates their growth and thickens them, resulting in a characteristic peanut/boxy shape when viewed edge on. Using N-body simulations of galactic disks…

Astrophysics · Physics 2009-11-10 Inma Martinez-Valpuesta , Isaac Shlosman

We present simulations of bar-unstable stellar discs in which the bars thicken into box/peanut shapes. Detailed analysis of the evolution of each model revealed three different mechanisms for thickening the bars. The first mechanism is the…

Astrophysics of Galaxies · Physics 2020-05-27 J. A. Sellwood , Ortwin Gerhard

The buckling process in stellar bars is full of unsolved issues. We analyze the origin of the buckling instability in stellar bars using high-resolution N-body simulations. Previous studies have promoted the nonresonant firehose instability…

Astrophysics of Galaxies · Physics 2023-03-06 Xingchen Li , Isaac Shlosman , Daniel Pfenniger , Clayton Heller

For the first time, we investigate the resonant structure of $N$-body galactic bar at the stage of buckling using action-angle variables. We studied the evolution of vertical actions ($J_z$) and angles associated with vertical resonance…

Astrophysics of Galaxies · Physics 2025-06-05 Viktor D. Zozulia , Natalia Ya. Sotnikova , Anton A. Smirnov

Evolution of stellar bars in disk galaxies is accompanied by dynamical instabilities and secular changes. Following the vertical buckling instability, the bars are known to weaken dramatically and develop a pronounced boxy/peanut shape when…

Astrophysics · Physics 2009-11-13 Inma Martinez-Valpuesta , Isaac Shlosman , Clayton Heller

By using $N$-body and hydro simulations, we study the formation and evolution of bars in galaxies with significant gas content focusing on the phenomenon of the buckling instability. The galaxies are initially composed of a spherical dark…

Astrophysics of Galaxies · Physics 2020-02-26 Ewa L. Lokas

We investigate the evolution of two bars formed in fully self-consistent hydrodynamic simulations of the formation of Milky Way-mass galaxies. One galaxy shows higher central mass concentration and has a longer and stronger bar than the…

Astrophysics of Galaxies · Physics 2015-04-29 Takashi Okamoto , Mari Isoe , Asao Habe

We use high resolution numerical simulations in order to analyze the stellar bar evolution in spinning dark matter (DM) halos. Previous works have shown that the halo spin has a substantial effect on the bar evolution and can lead to bar…

Astrophysics of Galaxies · Physics 2023-09-13 Xingchen Li , Isaac Shlosman , Clayton Heller , Daniel Pfenniger

Simulations have shown that bars are subject to a vertical buckling instability that transforms thin bars into boxy or peanut-shaped structures, but the physical conditions necessary for buckling to occur are not fully understood. We use…

Astrophysics of Galaxies · Physics 2017-08-23 Zhao-Yu Li , Luis C. Ho , Aaron J. Barth

Galactic bars are unstable to a vertical buckling instability which heats the disk and in some cases forms a boxy/peanut shaped bulge. We analyze the buckling instability as an application of classical Euler buckling followed by nonlinear…

Astrophysics of Galaxies · Physics 2020-01-22 Angela Collier

We carry out a detailed orbit analysis of gravitational potentials selected at different times from an evolving self-consistent model galaxy consisting of a two-component disk (stars+gas) and a live halo. The results are compared with a…

Astrophysics · Physics 2009-10-30 I. Berentzen , C. H. Heller , I. Shlosman , K. J. Fricke

It is well-established that strong bars rotating in dense halos generally slow down as they lose angular momentum to the halo through dynamical friction. Angular momentum exchanges between the bar and halo particles take place at…

Astrophysics · Physics 2009-11-13 J. A. Sellwood , Victor P. Debattista

The majority of massive disk galaxies, including our own, have stellar bars with vertically thick inner regions -- so-called "boxy/peanut-shaped" (B/P) bulges. The most commonly suggested mechanism for the formation of B/P bulges is a…

Astrophysics of Galaxies · Physics 2016-07-20 Peter Erwin , Victor P. Debattista

Based on N-body simulations, we show that realistic galactic disks are subject to bending instabilities of fire-hose type when the disks are substantially self-gravitating, that is, if they contain dark matter distributed in the disk.…

Astrophysics · Physics 2007-05-23 Y. Revaz , D. Pfenniger

We find that nuclear rings in barred galaxies can be subject to a new type of non-self-gravitational dynamical instability. The instability leads to the formation of gaseous molecular bars with pattern speeds which are substantially slower…

Astrophysics · Physics 2009-11-06 Clayton Heller , Isaac Shlosman , Peter Englmaier

Elongated bar-like features are ubiquitous in galaxies, occurring at the centers of approximately two-thirds of spiral disks in the nearby Universe. Due to gravitational interactions between the bar and the other components of galaxies, it…

Many of the stars in the Galaxy were formed in binary systems. The widest of these can eventually become disrupted due to a combination of kicks from passing stars and the Galactic tidal field. If the Galactic disk were purely axisymmetric,…

Astrophysics of Galaxies · Physics 2024-07-11 Tomer D. Yavetz

The dynamic evolution of galactic bars in standard $\Lambda$CDM models is dominated by angular momentum loss to the dark matter haloes via dynamical friction. Traditional approximations to dynamical friction are formulated using the…

Astrophysics of Galaxies · Physics 2022-04-29 Rimpei Chiba , Ralph Schönrich
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