Revealing mass distributions of dwarf spheroidal galaxies in the Subaru-PFS era

TL;DR

This paper discusses how upcoming large-scale spectroscopic surveys with Subaru-PFS will improve the measurement of dark matter distributions in dwarf spheroidal galaxies by addressing current uncertainties and degeneracies.

Contribution

It proposes utilizing the Subaru-PFS instrument combined with Hyper Suprime Cam imaging to obtain large kinematic samples, reducing uncertainties in dark matter profile measurements.

Findings

Enhanced kinematic data will improve dark matter profile constraints.

Large fiber coverage enables better foreground contamination removal.

The approach will significantly advance understanding of dark matter in dwarf galaxies.

Abstract

The Galactic dwarf spheroidal galaxies (dSphs) provide valuable insight into dark matter (DM) properties and its role in galaxy formation. Their close proximity enables the measurement of line-of-sight velocities for resolved stars, which allows us to study DM halo structure. However, uncertainties in DM mass profile determination persist due to the degeneracy between DM mass density and velocity dispersion tensor anisotropy. Overcoming this requires large kinematic samples and identification of foreground contamination. With 1.25 deg$^2$ and 2394 fibers, PFS plus pre-imaging with Hyper Suprime Cam will make significant progress in this undertaking.