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Boxy/peanut bulges in disc galaxies have been associated to stellar bars. We analyse their properties in a large sample of $N$-body simulations, using different methods to measure their strength, shape and possible asymmetry, and then…

天体物理学 · 物理学 2008-01-22 Martinez-Valpuesta , I. , Athanassoula , E.

We study evolution of galactic bars using suite of very high-resolution zoom-in cosmological simulations of galaxies at z ~ 9-2. Our models were chosen to lie within similar mass DM halos, log(Mvir/Mo) ~ 11.65 +- 0.05, at z=6, 4, and 2, in…

星系天体物理 · 物理学 2022-08-03 Da Bi , Isaac Shlosman , Emilio Romano-Diaz

We use high-resolution numerical simulations to follow the barred disk evolution in a suite of models with progressively more massive stellar bulges, with bulge-to-total (disk$+$bulge) mass ratios of $B/T\sim 0-0.25$, embedded in dark…

星系天体物理 · 物理学 2023-10-03 Xingchen Li , Isaac Shlosman , Daniel Pfenniger , Clayton Heller

The Milky Way hosts a flattened nuclear stellar disc (NSD) that dominates the gravitational potential in the inner few hundred parsecs. Whether the NSD is purely axisymmetric or contains a nuclear bar remains an open question. We test for…

Our Galaxy is known to contain a central boxy/peanut-shaped bulge, yet the importance of a classical, pressure-supported component within the central part of the Milky Way is still being debated. It should be most visible at low…

It has been suggested that the boxy and peanut-shaped bulges found in some edge-on galaxies are galactic bars viewed from the side. We investigate this hypothesis by presenting emission-line spectra for a sample of 10 edge-on galaxies that…

天体物理学 · 物理学 2016-08-30 Michael R. Merrifield , Konrad Kuijken

Boxy/peanut bulges in disk galaxies have been associated to stellar bars. In this talk, we discuss the different properties of such bulges and their relation with the corresponding bar, using a very large sample of a few hundred numerical…

天体物理学 · 物理学 2009-11-13 I. Martinez-Valpuesta , E. Athanassoula

Most of the observed and simulated galactic bars are symmetric in the face-on view. However, there are indeed cases of bars that are off-center with respect to the disk or have an asymmetric shape. The only well-known example showing both…

星系天体物理 · 物理学 2021-12-01 Ewa L. Lokas

Bar driven secular evolution plays a key role in changing the morphology and kinematics of disk galaxies, leading to the formation of rapidly rotating boxy/peanut bulges. If these disk galaxies also hosted a preexisting classical bulge, how…

星系天体物理 · 物理学 2012-12-20 Kanak Saha , Ortwin Gerhard

Near the minor axis of the Galactic bulge, at latitudes b < -5 degrees, the red giant clump stars are split into two components along the line of sight. We investigate this split using the three fields from the ARGOS survey that lie on the…

The Galactic bulge and bar are critical to our understanding of the Milky Way. However, due to the lack of reliable stellar distances, the structure and kinematics of the bulge/bar beyond the Galactic center have remained largely…

I present examples of how chemo-dynamical N-body simulations can help understanding the structure and evolution of the inner Galaxy. Such simulations reproduce the observed links between kinematics, morphology and chemistry in the bar/bulge…

星系天体物理 · 物理学 2018-08-22 E. Athanassoula

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…

星系天体物理 · 物理学 2017-02-07 E. V. Polyachenko , P. Berczik , A. Just

We model the split red clump of the Galactic bulge in OGLE-III photometry, and compare the results to predictions from two N-body models. Our analysis yields precise maps of the brightness of the two red clumps, the fraction of stars in the…

Double bars are thought to be important features for secular evolution in the central regions of galaxies. However, observational evidence about their origin and evolution is still scarce. We report on the discovery of the first Box-Peanut…

We study the effects of bulge elongation on the star formation activity in the centers of spiral galaxies using the data from the Sloan Digital Sky Survey Data Release 7. We construct a volume-limited sample of face-on spiral galaxies with…

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…

星系天体物理 · 物理学 2016-08-17 Evgeny Polyachenko , Peter Berczik , Andreas Just

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…

星系天体物理 · 物理学 2023-03-06 Xingchen Li , Isaac Shlosman , Daniel Pfenniger , Clayton Heller

We analyze the first-year MACHO collaboration observations of microlensing towards the Galactic center using a new direct likelihood technique that is sensitive to the distribution of the events on the sky. We consider the full set of 41…

天体物理学 · 物理学 2007-05-23 Geza Gyuk

A new view on our Galaxy has recently emerged, with large consequences on its formation scenarios. Not only new dwarf satellites have been detected, still orbiting and tidally disrupting, but also a multitude of stellar streams or tidal…

天体物理学 · 物理学 2007-05-23 F. Combes