Title: Estimating masses and density slopes of dwarf spheroidal galaxies

Abstract:
Measurements of mass and density slopes in dark matter dominated dwarf spheroidal galaxies 
are of great importance for testing the theories of structure formation. We use N-body 
simulations of the tidal evolution of a disky dwarf galaxy orbiting the Milky Way to construct 
realistic models of dwarf spheroidal (dSph) galaxies of the Local Group. We generate mock 
kinematical data sets from the simulations and use them to test the reliability of simple mass 
and density slope estimators recently proposed in the literature. The dSphs formed by tidal 
stirring are inherently triaxial and we observe them along the three principal axes. We measure 
the half-light radii and the line-of-sight velocity dispersions and use them to estimate the mass. 
We find that the mass is significantly overestimated when the dwarf is seen along the longest 
axis of the stellar component and underestimated when observed along the shortest axis. We 
provide a formula that quantifies the systematic error in the estimated mass with respect to the 
true one as a function of the galaxy shape and line of sight. We also discuss a similar bias in 
the inferred slope of the density profile. The inferred slopes are systematically over- or 
underestimated, depending on the line of sight. In particular, when the dwarf is seen along the 
longest axis of the stellar component, a significantly shallower density profile is inferred than the 
real one measured from the simulations.