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Related papers: Phase spirals across galactic disks I: Exploring d…

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The distribution of stars in the Milky Way disc shows a spiral structure--the Snail--in the space of velocity and position normal to the Galactic mid-plane. The Snail appears as straight lines in the vertical frequency--vertical phase plane…

Astrophysics of Galaxies · Physics 2023-04-05 Neige Frankel , Jo Bovy , Scott Tremaine , David W. Hogg

Gaia data have revealed vertically asymmetric phase-space structures in the Milky Way (MW) disc, such as phase spirals, indicating vertical oscillations. These oscillations exhibit two distinct modes: the bending mode and the breathing…

Astrophysics of Galaxies · Physics 2025-08-14 Tetsuro Asano , Michiko S. Fujii , Junichi Baba , Simon Portegies Zwart , Jeroen Bédorf

We present evidence that recurrent spiral activity, long manifested in simulations of disk galaxies, results from the super-position of a few transient spiral modes. Each mode lasts between 5 and 10 rotations at its corotation radius where…

Astrophysics of Galaxies · Physics 2015-06-19 J. A. Sellwood , R. G. Carlberg

The origin of spiral patterns in galaxies is still not fully understood. Similar features also develop readily in N-body simulations of isolated cool, collisionless disks, yet even here the mechanism has yet to be explained. In this series…

Astrophysics of Galaxies · Physics 2015-06-04 J. A. Sellwood

This paper continues a series reporting different aspects of the behaviour of disc galaxy simulations that support spiral instabilities. The focus in this paper is to demonstrate how linear spiral instabilities saturate and decay, and how…

Astrophysics of Galaxies · Physics 2023-03-08 J A Sellwood , R G Carlberg

By combining the {\it LAMOST} and {\it Gaia} data, we investigate the vertical phase mixing across the Galactic disk. Our results confirm the existence of the phase space snail shells (or phase spirals) from 6 to 12 kpc. We find that…

Astrophysics of Galaxies · Physics 2021-04-28 Zhao-Yu Li

N-body simulations of disc galaxies that display recurrent transient spiral patterns are comparatively easy to construct, but are harder to understand. In this paper, I summarise the evidence from such experiments that the spiral patterns…

Astrophysics of Galaxies · Physics 2010-11-19 J. A. Sellwood

By means of N-body simulations we study the response of a galactic disc to a minor merger event. We find that non-self-gravitating, spiral-like features are induced in the thick disc. As we have shown in a previous work, this "ringing" also…

Astrophysics of Galaxies · Physics 2015-05-28 Facundo A. Gómez , Ivan Minchev , Álvaro Villalobos , Brian W. O'Shea , Mary E. K. Williams

The evolution of large-scale magnetic fields in disk galaxies is investigated numerically. The gasdynamical simulations in a disk perturbed by spiral or bar potential are incorporated into the kinematic calculations of induction equations…

Astrophysics · Physics 2007-05-23 K. Otmianowska-Mazur , M. Chiba

We investigate the influence of ram-pressure stripping on the internal gas kinematics of simulated spiral galaxies. Additional emphasis is put on the question of how the resulting distortions of the gaseous disc are visible in the rotation…

Astrophysics · Physics 2009-11-13 T. Kronberger , W. Kapferer , S. Unterguggenberger , S. Schindler , B. L. Ziegler

The manifold theory of barred-spiral structure provides a dynamical mechanism explaining how spiral arms beyond the ends of galactic bars can be supported by chaotic flows extending beyond the bar's co-rotation zone. We discuss its…

Astrophysics of Galaxies · Physics 2019-01-23 C. Efthymiopoulos , P. E. Kyziropoulos , R. I. Paez , K. Zouloumi , G. A. Gravvanis

As star clusters are expected to form with low star formation efficiencies, the gas in the cluster is expelled quickly and early in their development: the star cluster "pops." This leads to an unbound stellar system, evolving in the…

Astrophysics of Galaxies · Physics 2015-06-17 G. N. Candlish , R. Smith , M. Fellhauer , B. K. Gibson , P. Kroupa , P. Assmann

Spiral shocks are potentially a major source of turbulence in the interstellar medium. To address this problem quantitatively, we use numerical simulations to investigate gas flow across spiral arms in vertically stratified,…

Astrophysics · Physics 2011-02-11 Chang-Goo Kim , Woong-Tae Kim , Eve C. Ostriker

By performing local three-dimensional MHD simulations of stratified accretion disks, we investigate disk winds driven by MHD turbulence. Initially given weak vertical magnetic fields are effectively amplified by magnetorotational…

Astrophysics · Physics 2015-05-13 T. K. Suzuki , S. Inutsuka

A new type of wind - a conical wind - has been discovered in axisymmetric magnetohydrodynamic simulations of the disk-magnetosphere interaction in cases where the magnetic field of the star is bunched into an X-type configuration. Such a…

Solar and Stellar Astrophysics · Physics 2009-01-28 M. M. Romanova , G. V. Ustyugova , A. V. Koldoba , R. V. E. Lovelace

Spiral density wave theory attempts to describe the spiral pattern in spiral galaxies in terms of a long-lived wave structure with a constant pattern speed in order to avoid the winding dilemma. The pattern is consequently a rigidly…

Astrophysics of Galaxies · Physics 2015-05-30 Daisuke Kawata , Robert J. J. Grand , Mark Cropper

The recent discovery of a spiral pattern in the vertical kinematic structure in the solar neighborhood provides a prime opportunity to study non-equilibrium dynamics in the Milky Way from local stellar kinematics. Furthermore, results from…

Astrophysics of Galaxies · Physics 2023-02-21 Elise Darragh-Ford , Jason A. S. Hunt , Adrian M. Price-Whelan , Kathryn V. Johnston

Recent observations have shown that star-forming galaxies like our own Milky Way evolve kinematically into ordered thin disks over the last ~8 billion years since z=1.2, undergoing a process of "disk settling." For the first time, we study…

Astrophysics of Galaxies · Physics 2015-06-22 Susan A. Kassin , Alyson Brooks , Fabio Governato , Benjamin J. Weiner , Jonathan P. Gardner

I use N-body simulations with two mass species of particles to demonstrate that disk galaxy simulations are subject to collisional relaxation at a higher rate than is widely assumed. Relaxation affects the vertical thickness of the disk…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 J. A. Sellwood

We perform numerical simulations of a stellar galactic disk with initial conditions chosen to represent an unrelaxed population which might have been left following a merger. Stars are unevenly distributed in radial action angle, though the…

Astrophysics of Galaxies · Physics 2009-11-13 I. Minchev , A. C. Quillen , M. Williams , K. C. Freeman , J. Nordhaus , A. Siebert , O. Bienayme