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We use high resolution collisionless $N$-body simulations to study the secular evolution of disk galaxies and in particular the final properties of disks that suffer a bar and perhaps a bar-buckling instability. Although we find that bars…

Astrophysics · Physics 2009-11-10 Victor P. Debattista , C. Marcella Carollo , Lucio Mayer , Ben Moore

We present a novel interpretation of the previously puzzling different behaviours of stellar populations of the Milky Way's bulge. We first show, by means of pure N-body simulations, that initially co-spatial stellar populations with…

Astrophysics of Galaxies · Physics 2017-06-08 Victor P. Debattista , Melissa Ness , Oscar A. Gonzalez , K. Freeman , Manuela Zoccali , Dante Minniti

The Milky Way has a barred bulge. This article summarizes the current understanding of the main structural parameters and pattern speed of the bar, and compares predicted values for the microlensing optical depth with the bulge microlensing…

Astrophysics · Physics 2008-11-26 Ortwin Gerhard

We study HST/NICMOS H-band images of bulges of two equal-sized samples of early- (T(RC3) < 4) and late-type spiral (mainly Sbc-Sc) galaxies matched in outer disk axis ratio. We find that bulges of late-type spirals are more elongated than…

Astrophysics · Physics 2009-11-07 K. Fathi , R. F. Peletier

In this work, we explore the nature of $z>1$ galactic bars. Once thought to be highly transient, our results demonstrate otherwise. Our sample consists of nine massive ($>10^{10.5}\,\rm M_{\odot}$) star-forming barred-spiral galaxies at…

We show by numerical simulations that a purely stellar dynamical model composed of an exponential disc, a cuspy bulge, and an NFW halo with parameters relevant to the Milky Way Galaxy is subject to bar formation. Taking into account the…

Astrophysics of Galaxies · Physics 2016-08-17 Evgeny Polyachenko , Peter Berczik , Andreas Just

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

Angular momentum redistribution within barred galaxies drives their dynamical evolution. Angular momentum is emitted mainly by near-resonant material in the bar region and absorbed by resonant material mainly in the outer disc and in the…

Astrophysics · Physics 2009-11-10 E. Athanassoula

We present results for the chemical evolution of the Galactic bulge in the context of an inside-out formation model of the Galaxy. A supernova-driven wind was also included in analogy with elliptical galaxies. New observations of chemical…

Astrophysics · Physics 2007-05-23 Silvia Ballero , Francesca Matteucci , Livia Origlia

Present in over 45% of local spirals, boxy and peanut-shaped bulges are generally interpreted as edge-on bars and may represent a key phase in the evolution of bulges. Aiming to test such claims, the kinematic properties of self-consistent…

Astrophysics · Physics 2009-11-10 M. Bureau , E. Athanassoula

Bar fractions depend on the properties of the host galaxies, which are closely related to the formation and evolution of bars. However, observational studies do not provide consistent results. We investigate the bar fraction and its…

Astrophysics of Galaxies · Physics 2019-02-27 Yun Hee Lee , Hong Bae Ann , Myeong-Gu Park

We have done a robust statistical analysis of UBV color profiles of 257 Sbc barred and unbarred galaxies. We found that there is an excess of barred galaxies among the objects with null or positive (bluish inward) color gradients, which…

Astrophysics · Physics 2007-05-23 D. A. Gadotti , S. dos Anjos

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

Many barred galaxies, possibly including the Milky Way, have cusps in the centres. There is a widespread belief, however, that usual bar instability taking place in bulgeless galaxy models is impossible for the cuspy models, because of the…

Astrophysics of Galaxies · Physics 2017-02-07 E. V. Polyachenko , P. Berczik , A. Just

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

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

The bar pattern speed ($\Omega_{\rm b}$) is defined as the rotational frequency of the bar, and it determines the bar dynamics. Several methods have been proposed for measuring $\Omega_{\rm b}$. The non-parametric method proposed by…

With the steady increase of the sample size of observed microlenses towards the central regions of the Galaxy, the main source of the uncertainty in the lens mass will shift from the simple Poisson noise to the intrinsic non-uniqueness of…

Astrophysics · Physics 2009-10-30 HongSheng Zhao , P. Tim de Zeeuw

(Abridged) A variety of formation scenarios was proposed to explain the diversity of properties observed in bulges. Studying their intrinsic shape can help in constraining the dominant mechanism at the epochs of their assembly. The…

Astrophysics · Physics 2015-05-13 J. Mendez-Abreu , J. A. L. Aguerri , E. M. Corsini , E. Simonneau

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