Stellar Density Profiles of Dwarf Spheroidal Galaxies

A. G. Moskowitz, M. G. Walker

Published 2019-10-22Version 1

We apply a flexible parametric model, a combination of generalized Plummer profiles, to infer the shapes of the stellar density profiles of the Milky Way's satellite dwarf spheroidal galaxies (dSphs). We apply this model to 38 dSphs using star counts from the Sloan Digital Sky Survey, PanStarrs-1 Survey, and Dark Energy Survey. Using mock data, we examine systematic errors associated with modelling assumptions and identify conditions under which our model can identify "non-standard" stellar density profiles that have central cusps and/or steepened outer slopes. Applying our model to real dwarf spheroidals, we do not find evidence for centrally cusped density profiles among the ~10 Milky Way satellites for which our tests with mock data indicate there would be sufficient detectability. We do detect steepened (with respect to a standard Plummer model) outer profiles in several dSphs - Fornax, Leo I, Leo II, Reticulum II - which may point to distinct evolutionary pathways for these objects. However, the outer slope of the stellar density profile does not yet obviously correlate with other observed galaxy properties.