Title: Dark Matter Constraints from the Milky Way and the Dwarf Spheroidal Galaxies

Place: Seminar del DAA. Jeroni Muñoz Research Building, fourth floor, in Burjassot.

Day: Monday, march 31, 2025. Time: 14:30.

Abstract:

The Milky Way (MW) plays a fundamental role in testing a wide range of Dark Matter (DM) theories. Upcoming photometric (LSST, EUCLID, ROMAN) and spectroscopic (DESI, 4MOST, WEAVE) surveys of dwarf spheroidal galaxies (dSphs), combined with astrometric data from Gaia DR4, will place unprecedented constraints on the DM distribution in both the outer regions of the MW and the dwarf spheroidal galaxies (dSphs), the most DM-dominated galaxies of the Universe.
In this talk I will discuss the latests results from my group at Edinburgh on these two fronts.
First, I will discuss how the recent accretion of the Large Magellanic Cloud (LMC) has driven the MW out of dynamical equilibrium. A key signature of this interaction is a strong kinematic dipole in the motions of distant halo stars, reflecting the displacement of the MW disc from the Galactic barycentre.
In the second part, I will focus on dSphs and demonstrate that DM subhaloes can capture passing stars with small relative velocities, temporarily forming "luminous" systems with unusual properties: (i) large sizes for their luminosity, (ii) stellar populations indistinguishable from their host galaxy, and (iii) extreme DM-dominated mass-to-light ratios. I will estimate the number and properties of these objects across different galaxies and discuss several `anomalous' stellar systems—currently classified as star clusters in the Fornax and Eridanus II dSphs— which exhibit these characteristics.