20-24 March 2023
Haus H, Telegrafenberg
Europe/Berlin timezone

The coherent motion of Cen A dwarf satellite galaxies as a challenge for cosmology

24 Mar 2023, 11:20
25m
Haus H, Telegrafenberg

Haus H, Telegrafenberg

Potsdam, Germany
Invited topical talk SESSION 5 : Near-field cosmology and galaxy masses beyond the Local Group SESSION 5 : Near-field cosmology and galaxy masses beyond the Local Group

Speaker

Oliver Müller (Institute of Physics, Laboratory of Astrophysics, École Polytechnique Fédérale de Lausanne (EPFL))

Description

The plane-of-satellites problem is one of the most severe small-scale challenges for the standard Λ cold dark matter (ΛCDM) cosmological model: Several dwarf galaxies around the Milky Way and Andromeda co-orbit in thin, planar structures. A similar case has been identified around the nearby elliptical galaxy Centaurus A (Cen A). We studied the satellite system of Cen A with line-of-sight velocities from VLT/MUSE observations and TRGB distances from VLT/FORS2 and HST observations. Out of 28 dwarf galaxies with measured velocities 21 share a coherent motion and are arranged in a flattened structure. Similarly, flattened and coherently moving structures are found only in 0.2% of Cen A analogs in the Illustris-TNG100 cosmological simulation, independently of whether we use its dark-matter-only or hydrodynamical run. These analogs are not co-orbiting, and they arise only by chance projection, thus they are short-lived structures in such simulations. Our findings indicate that the observed co-rotating planes of satellites are a persistent challenge for ΛCDM, which is largely independent from baryon physics.

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Primary author

Oliver Müller (Institute of Physics, Laboratory of Astrophysics, École Polytechnique Fédérale de Lausanne (EPFL))

Co-authors

Dr Marcel S. Pawlowski (Leibniz-Institut fur Astrophysik Potsdam (AIP)) Federico Lelli Katja Fahrion Ms Marina Rejkuba (ESO) Michael Hilker Kosuke Jamie Kanehisa (Leibniz-Institut für Astrophysik Potsdam) Noam Libeskind Prof. Helmut Jerjen (Australian National University)

Presentation Materials