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Constraints on the Galactic bulge/bar structure and formation history from stellar kinematics and metallicities mainly come from relatively high-latitude fields (|b|>4) where a complex mix of stellar population is seen. We aim here to…

We use fully self-consistent N-body simulations of barred galaxies to show that dynamical friction from a dense dark matter halo dramatically slows the rotation rate of bars. Our result supports previous theoretical predictions for a bar…

Astrophysics · Physics 2010-01-28 Victor P. Debattista , J. A. Sellwood

The bar formation is still an open problem in modern astrophysics. In this paper we present numerical simulation performed with the aim of analyzing the growth of the bar instability inside stellar-gaseous disks, where the star formation is…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Anna Curir , Valentina de Romeri , Giuseppe Murante

We review general observational properties of bars in galaxies, and relations between bars, their dynamics, and (circum)nuclear activity. We consider new measurements of bar fractions and of the distribution of bars with host type, bar…

Astrophysics · Physics 2009-09-25 Johan H. Knapen

Bars are an elongated structure that extends from the centre of galaxies, and about one-third of disk galaxies are known to possess bars. These bars are thought to form either through a physical process inherent in galaxies, or through an…

Astrophysics of Galaxies · Physics 2019-06-26 Yongmin Yoon , Myungshin Im , Gwang-Ho Lee , Seong-Kook Lee , Gu Lim

We describe fully self-consistent N-body experiments of barred galaxies with massive halos. A rotating bar is braked through dynamical friction with the halo, which occurs on a short time scale when the central density of the halo is high.…

Astrophysics · Physics 2007-05-23 Victor P. Debattista , J. A. Sellwood

The Milky Way's bar dominates the orbits of stars and the flow of cold gas in the inner Galaxy, and is therefore of major importance for Milky Way dynamical studies in the Gaia era. Here we discuss the pronounced peanut shape of the…

Astrophysics of Galaxies · Physics 2018-03-14 Ortwin Gerhard , Christopher Wegg

Bars have a complex three-dimensional shape. In particular their inner part is vertically much thicker than the parts further out. Viewed edge-on, the thick part of the bar is what is commonly known as a boxy-, peanut- or X- bulge and…

Astrophysics of Galaxies · Physics 2015-12-09 E. Athanassoula

Isolated barred galaxies evolve by redistributing their internal angular momentum, which is emitted mainly at the inner disc resonances and absorbed mainly at the resonances in the outer disc and the halo. This causes the bar to grow…

Astrophysics · Physics 2007-05-23 E. Athanassoula

We provide the first quantitative evidence for the deceleration of the Galactic bar from local stellar kinematics in agreement with dynamical friction by a typical dark matter halo. The kinematic response of the stellar disk to a…

Astrophysics of Galaxies · Physics 2023-08-04 Rimpei Chiba , Jennifer K. S. Friske , Ralph Schönrich

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

This chapter reviews theoretical work on the stellar dynamics of galaxy disks. All the known collective global instabilities are identified, and their mechanisms described in terms of local wave mechanics. A detailed discussion of warps and…

Astrophysics of Galaxies · Physics 2015-05-19 J. A. Sellwood

The evolution of a stellar bar transforms not only the galactic disk, but also the host dark matter halo. We present high resolution, fully self-consistent N-body simulations that clearly demonstrate that dark matter halo central density…

Astrophysics · Physics 2009-11-10 Kelly Holley-Bockelmann , Martin Weinberg , Neal Katz

The spin of dark halos has been shown to significantly affect bar formation and evolution in disk galaxies. To understand the physical role of the halo spin on bar formation, we run $N$-body simulations of isolated, Milky Way-sized galaxies…

Astrophysics of Galaxies · Physics 2024-06-14 Dajeong Jang , Woong-Tae Kim

Bars in galaxies may develop through a global instability or due to an interaction with another system. We study bar formation in disky dwarf galaxies orbiting a Milky Way-like galaxy. We employ $N$-body simulations to study the impact of…

Astrophysics of Galaxies · Physics 2017-06-28 Grzegorz Gajda , Ewa L. Lokas , E. Athanassoula

The inner disc of the local group galaxy M33 appears to be in settled rotational balance, and near IR images reveal a mild, large-scale, two-arm spiral pattern with no strong bar. We have constructed N-body models that match all the…

Astrophysics of Galaxies · Physics 2019-05-08 J. A. Sellwood , Juntai Shen , Zhi Li

The Euler buckling of rods is a long-studied mechanical instability, and it remains relevant to this day, as the constituent components in many biological and physical systems are linear polymers, such as microtubules or carbon nanotubes.…

Statistical Mechanics · Physics 2026-05-22 Richard Huang , David R. Nelson , Suraj Shankar

Stellar bars are a common feature in massive disc galaxies. On a theoretical ground, the response of gas to a bar is generally thought to cause nuclear starbursts and, possibly, AGN activity once the perturbed gas reaches the central…

Astrophysics of Galaxies · Physics 2015-10-28 R. Fanali , M. Dotti , D. Fiacconi , F. Haardt

Does the environment of a galaxy directly influence the kinematics of its bar? We present observational evidence that bars in high-density environments exhibit significantly slower rotation rates than bars in low-density environments.…

Astrophysics of Galaxies · Physics 2026-03-18 Natalia Puczek , Tobias Géron , Rebecca J. Smethurst , Chris J. Lintott

In this article we address the problem of Euler's buckling instability in a charged semi-flexible polymer that is under the action of a compressive force. We consider this instability as a phase transition and investigate the role of…

Soft Condensed Matter · Physics 2015-05-27 Khabat Ghamari , Ali Najafi