Speaker
Description
Nearby dwarf galaxies are strongly dark matter-dominated, making them ideal laboratories for testing empirical relations between dynamical and baryonic properties. A key example is the Radial Acceleration Relation (RAR), describing a tight correlation between baryonic and observed acceleration across a wide mass range. Whether this relation holds in the lowest-mass, dark matter–dominated dwarfs remains an open question, with hints of deviations from early studies.
We present radially resolved measurements of the RAR for 12 nearby dwarf galaxies with baryonic masses 10^4 < Mbar/M⊙ < 10^7.5, combining literature data with new measurements from the MUSE-Faint survey. Using stellar kinematics and Jeans modelling with GravSphere, we infer mass distributions and compare the resulting acceleration profiles with isolated dwarf galaxies from the EDGE simulations in a ΛCDM cosmology.
We find that most of the observed dwarf galaxies systematically lie above the low-mass extrapolation of the RAR, which was originally calibrated on more massive galaxies. The simulated EDGE dwarf galaxies exhibit a similar behaviour to the observed data, with a higher observed acceleration at a fixed baryonic acceleration compared to the extrapolated RAR. Additionally, there is significant scatter across galaxies, suggesting that the RAR is not universal for low-mass dwarf galaxies and that baryonic acceleration alone does not contain enough information to fully determine the observed acceleration, providing new near-field constraints on dark matter in the faintest galaxies.