The effect of warm gas on the buckling instability in galactic bars

Łokas, Ewa L.

doi:10.1051/0004-6361/201937165

Cited by 20 publications

(14 citation statements)

References 53 publications

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“…Two bar-driven processes can vertically thicken a bar. The higher radial velocity dispersion due to orbital motion along the bar's major axis makes the bar susceptible to the buckling instability (Raha et al 1991;Merritt & Sellwood 1994;Debattista et al 2006;Martinez-Valpuesta et al 2006;Collier 2020;Łokas 2020).…”

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confidence: 99%

Predicted trends in Milky Way bulge proper motion rotation curves: future prospects for HST and LSST

Gough-Kelly

Debattista

Clarkson

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We use an N-body+smoothed particle hydrodynamics simulation of an isolated barred galaxy to study the age dependence of bulge longitudinal proper motion (μl) rotation curves. We show that close to the minor axis (|l| ∼ 0○) the relatively young stars rotate more rapidly than the old stars, as found by Hubble Space Telescope in the Milky Way’s bulge. This behaviour would be expected also if the Milky Way were unbarred. At larger |l| a different behaviour emerges. Because younger stars trace a strong bar, their Galactocentric radial motions dominate their μl at |l| ∼ 6○, leading to a reversal in the sign of $\left<{{\mu _l}}\right>$. This results in a rotation curve with forbidden velocities (negative $\left<{{\mu _l}}\right>$ at positive longitudes, and positive $\left<{{\mu _l}}\right>$ at negative longitudes). The old stars, instead, trace a much weaker bar and thus their kinematics are more axisymmetric, resulting in no forbidden velocities. We develop metrics of the difference in the $\left<{{\mu _l}}\right>$ rotation curves of young and old stars, and forbidden velocities. We use these to predict the locations where rotation curve reversals can be observed by HST and the Vera Rubin Telescope. Such measurements would represent support for the amplitude of the bar being a continuous function of age, as predicted by kinematic fractionation, in which the bar strength variations are produced purely by differences in the random motions of stellar populations at bar formation.

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confidence: 99%

Predicted trends in Milky Way bulge proper motion rotation curves: future prospects for HST and LSST

Gough-Kelly

Debattista

Clarkson

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…All these factors also affect the bar formation and buckling of the bar. The presence of gas, and classical bulge prevent bar formation whereas flyby interactions have been seen to produce bars (Łokas 2018;Smirnov & Sotnikova 2019;Łokas 2020). Studying the effect of various components of a galaxy on bar buckling and the galaxy environment, may provide constraints on the shapes of dark matter halos.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

The Effect of Dark Matter Halo Shape on Bar Buckling and Boxy/Peanut Bulges

Kumar,

Das,

Kataria

2021

Preprint

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It is well established that bars evolve significantly after they form in galaxy discs, often changing shape both in and out of the disc plane. In some cases they may bend or buckle out of the disc plane resulting in the formation of boxy/peanut/x-shape bulges. In this paper we show that the dark matter halo shape affects bar formation and buckling. We have performed N-body simulations of bar buckling in non-spherical dark matter halos and traced bar evolution for 8 Gyr. We find that bar formation is delayed in oblate halos, resulting in delayed buckling whereas bars form earlier in prolate halos leading to earlier buckling. However, the duration of first buckling remains almost comparable. All the models show two buckling events but the most extreme prolate halo exhibits three distinct buckling features. Bars in prolate halos also show buckling signatures for the longest duration compared to spherical and oblate halos. Since ongoing buckling events are rarely observed, our study suggests that most barred galaxies may have more oblate or spherical halos rather than prolate halos. Our measurement of BPX structures also shows that prolate halos promote bar thickening and disc heating more than oblate and spherical halos.

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“…We note that the interactions with these more massive galaxies appear to have little effect on the bar as it seems to grow steadily during this period. They may have, in fact, helped the bar grow by stripping the gas since galaxies with smaller gas fractions are known to form bars more easily (Shlosman & Noguchi 1993;Athanassoula et al 2013;Łokas 2020b).…”

Section: Interaction With Environmentmentioning

confidence: 99%

An interesting case of the formation and evolution of a barred galaxy in the cosmological context

Łokas

2020

A&A

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Elongated, bar-like galaxies without a significant disk component, with little rotation support and no gas, often form as a result of tidal interactions with a galaxy cluster, as was recently demonstrated using the IllustrisTNG-100 simulation. Galaxies that exhibit similar properties are, however, also found to be infalling into the cluster for the first time. We use the same simulation to study in detail the history of such a galaxy over cosmic time in order to determine its origin. The bar appears to be triggered at t = 6.8 Gyr by the combined effect of the last significant merger with a subhalo and the first passage of another dwarf satellite, both ten times less massive than the galaxy. The satellites deposit all their gas in the galaxy, contributing to its third and last star-formation episode, which perturbs the disk and may also contribute to the formation of the bar. The galaxy then starts to lose its gas and dark matter due to its passage near a group of more massive galaxies. The strongest interaction involves a galaxy 22 times more massive, leaving the barred galaxy with no gas and half of its maximum dark matter mass. During this time, the bar grows steadily, seemingly unaffected by the interactions, although they may have aided its growth by stripping the gas. The studied galaxy, together with two other similar objects briefly discussed in this Letter, suggest the existence of a new class of early-type barred galaxies and thereby demonstrate the importance of interactions in galaxy formation and evolution.

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The effect of warm gas on the buckling instability in galactic bars

Cited by 20 publications

References 53 publications

Predicted trends in Milky Way bulge proper motion rotation curves: future prospects for HST and LSST

Predicted trends in Milky Way bulge proper motion rotation curves: future prospects for HST and LSST

The Effect of Dark Matter Halo Shape on Bar Buckling and Boxy/Peanut Bulges

An interesting case of the formation and evolution of a barred galaxy in the cosmological context

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