Tidally induced velocity gradients in the Milky Way dwarf spheroidal satellites

Author:

Martínez-García Alberto Manuel12ORCID,del Pino Andrés3ORCID,Aparicio Antonio12ORCID

Affiliation:

1. Instituto de Astrofísica de Canarias , Calle Vía Láctea S/N, E-38205 La Laguna, Tenerife, Spain

2. Universidad de La Laguna, Dpto. Astrofísica , Avda. Astrofísico Fco. Sánchez S/N, E-38206 La Laguna, Tenerife, Spain

3. Centro de Estudios de Física del Cosmos de Aragón (CEFCA) , Unidad Asociada al CSIC, Plaza San Juan 1, E-44001 Teruel, Spain

Abstract

ABSTRACT We present a kinematic study of six dwarf spheroidal galaxies (dSph) satellites of the Milky Way (MW), namely Carina, Draco, Fornax, Sculptor, Sextans, and Ursa Minor. We combine proper motions (PMs) from the Gaia Data Release 3 (DR3) and line-of-sight velocities (vlos) from the literature to derive their 3D internal kinematics and to study the presence of internal velocity gradients. We find velocity gradients along the line-of-sight for Carina, Draco, Fornax, and Ursa Minor, at ≥1σ level of significance. The value of such gradients appears to be related to the orbital history of the dwarfs, indicating that the interaction with the MW is causing them. Dwarfs that are close to the MW and moving towards their orbits pericentres show, on average, larger velocity gradients. On the other hand, dwarfs that have recently left their orbits pericentres show no significant gradients. Lastly, dwarfs located at large Galactocentric distances show gradients with an intermediate intensity. Our results would indicate that the torque caused by the strong tidal forces exerted by the MW induces a strong velocity gradient when the dwarfs approach their orbits pericentres. During the pericentre passage, the rapid change in the forces direction would disrupt such gradient, which may steadily recover as the galaxies recede. We assess our findings by analysing dwarfs satellites from the TNG50 simulation. We find a significant increase in the intensity of the detected gradients as the satellites approach their pericentre, followed by a sharp drop as they abandon it, supporting our results for the dSphs of the MW.

Funder

Agencia Estatal de Investigación

MICINN

European Union

Publisher

Oxford University Press (OUP)

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 7 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Fuzzy dark matter dynamics in tidally perturbed dwarf spheroidal galaxy satellites;Journal of Cosmology and Astroparticle Physics;2024-03-01

2. The accretion history of the Milky Way: III. Hydrodynamical simulations of Galactic dwarf galaxies at first infall;Monthly Notices of the Royal Astronomical Society;2023-11-24

3. Small-scale stellar haloes: detecting low surface brightness features in the outskirts of Milky Way dwarf satellites;Monthly Notices of the Royal Astronomical Society;2023-10-31

4. Internal kinematics of dwarf satellites of MW/M31-like galaxies in TNG50;Monthly Notices of the Royal Astronomical Society;2023-09-27

5. The extended ‘stellar halo’ of the Ursa Minor dwarf galaxy;Monthly Notices of the Royal Astronomical Society;2023-08-16

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