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We describe a method to extract resonant orbits from N-body simulations exploiting the fact that they close in a frame rotating with a constant pattern speed. Our method is applied to the N-body simulation of the Milky Way by Shen et al.…

Astrophysics of Galaxies · Physics 2015-08-06 Matthew Molloy , Martin C. Smith , Juntai Shen , N. W. Evans

The Galactic bulge is now considered to be the inner three-dimensional part of the Milky Way's bar. It has a peanut shape and is characterized by cylindrical rotation. In N-body simulations, box/peanut bulges arise from disks through bar…

Astrophysics of Galaxies · Physics 2014-08-04 Ortwin Gerhard

The predicted central densities of dark matter halos in LCDM models exceed those observed in some galaxies. Weinberg & Katz argue that angular momentum transfer from a rotating bar in the baryonic disk can lower the halo density, but they…

Astrophysics · Physics 2009-11-11 J. A. Sellwood

The circular speed curve of the Milky Way provides a key constraint on its mass distribution, reflecting the axisymmetric component of the gravitational potential. This is especially critical in the inner Galaxy ($R \lesssim 4$ kpc), where…

Astrophysics of Galaxies · Physics 2025-07-18 Junichi Baba

Galaxy models have long predicted that galactic bars slow down by losing angular momentum to their postulated dark haloes. When the bar slows down, resonance sweeps radially outwards through the galactic disc while growing in volume,…

Astrophysics of Galaxies · Physics 2023-08-04 Rimpei Chiba , Ralph Schönrich

We discuss the morphology, photometry and kinematics of the bars which have formed in three N-body simulations. These have initially the same disc and the same halo-to-disc mass ratio, but their haloes have very different central…

Astrophysics · Physics 2009-11-07 E. Athanassoula , A. Misiriotis

It has been suggested that the peanut-shaped bulges seen in some edge-on disk galaxies are due to the presence of a central bar. Although bars cannot be detected photometrically in edge-on galaxies, we show that barred potentials produce a…

Astrophysics · Physics 2016-08-30 Konrad Kuijken , Michael R. Merrifield

We measure and compare the pattern speeds of vertical breathing, vertical bending, and spiral density waves in two isolated N-body+SPH simulations, using windowed Fourier transforms over 1 Gyr time intervals. We show that the pattern speeds…

We study the bar instability in collisionless, rotating, anisotropic, stellar systems, using N-body simulations and also the matrix technique for calculation of modes with the perturbed collisionless Boltzmann equation. These methods are…

Astrophysics of Galaxies · Physics 2021-02-17 Philip G. Breen , Simon Rozier , Douglas C. Heggie , Anna Lisa Varri

The intrinsic photometric properties of inner and outer stellar bars within 17 double-barred galaxies are thoroughly studied through a photometric analysis consisting of: i) two-dimensional multi-component photometric decompositions, and…

Astrophysics of Galaxies · Physics 2020-04-01 A. de Lorenzo-Cáceres , J. Méndez-Abreu , B. Thorne , L. Costantin

We have used N-body simulations for the Milky Way to investigate the kinematic and structural properties of the old metal-poor stellar halo in the barred inner region of the Galaxy. We find that the extrapolation of the density distribution…

Astrophysics of Galaxies · Physics 2016-10-26 Angeles Pérez-Villegas , Matthieu Portail , Ortwin Gerhard

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

We show that direct detection and measurement of the vertically thickened parts of bars (so-called "boxy" or "peanut-shaped" bulges) is possible not only for edge-on galaxies but also for galaxies with moderate inclinations (i < 70 deg),…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Peter Erwin , Victor P. Debattista

We survey the properties of all orbit families in the rotating frame of a family of realistic triaxial potentials with central supermassive black holes (SMBHs). In such galaxies, most regular box orbits (vital for maintaining triaxiality)…

Astrophysics of Galaxies · Physics 2015-05-19 Alex T. Deibel , Monica Valluri , David Merritt

We present detailed numerical simulations of NGC 1433, an intermediate-type barred spiral showing strong morphological features including a secondary bar, nuclear ring, inner ring, outer pseudoring, and two striking, detached spiral arcs…

Astrophysics · Physics 2009-11-13 P. Treuthardt , H. Salo , P. Rautiainen , R. Buta

I review some of the work on bars which is closely linked to the bar/bulge system in our Galaxy. Several independent studies, using totally independent methods, come to the same results about the 3D structure of a bar, i.e., that a bar is…

Astrophysics of Galaxies · Physics 2015-06-04 E. Athanassoula

Until now, observations have caught up only a handful of galaxies in ongoing buckling action. Interestingly, N-body simulations over the past several decades show that almost every bar buckles or vertically thickens as soon as it reaches…

Astrophysics of Galaxies · Physics 2024-10-10 Sandeep Kumar Kataria

We construct a large set of dynamical models of the galactic bulge, bar and inner disk using the Made-to-Measure method. Our models are constrained to match the red clump giant density from a combination of the VVV, UKIDSS and 2MASS…

Astrophysics of Galaxies · Physics 2016-12-21 Matthieu Portail , Ortwin Gerhard , Christopher Wegg , Melissa Ness

We have modelled 38 barred galaxies by using near-IR and optical data from the Ohio State University Bright Spiral Galaxy Survey. We constructed the gravitational potentials of the galaxies from $H$-band photometry, assuming constant…

Astrophysics · Physics 2009-11-13 P. Rautiainen , H. Salo , E. Laurikainen

The inclination of M31 is too close to edge-on for a bar component to be easily recognised and is not sufficiently edge-on for a boxy/peanut bulge to protrude clearly out of the equatorial plane. Nevertheless, a sufficient number of clues…

Astrophysics · Physics 2009-11-11 E. Athanassoula , Rachael Lynn Beaton