Speaker
Description
Mock member stars for dwarf galaxies are constructed from the cosmological AURIGA simulation, which reflects the dynamical status of realistic stellar tracers. Axisymmetric Jeans Anisotropic Multi-Gaussian Expansion (JAM) modeling is applied to each system to recover the underlying matter distribution. The stellar or dark matter component individually is poorly recovered, but the total profile is constrained more reasonably. The mass within the half-mass radius of tracers is recovered the tightest, and the mass between 200 and 300 pc, M(200-300 pc), is an unbiasedly constrained ensemble. Quiescent Saggitarius dSph-like systems and star-forming systems with strong outflows show distinct features, with M(200-300 pc) mostly underestimated for the former, and likely overestimated for the latter. The biases correlate with the dynamical status, which is a result of contraction motions due to tidal effects in quiescent systems or galactic winds in star-forming systems, driving them out of equilibrium. By extrapolating the actual density profiles and the dynamical constraints down to scales below the resolution, we find the mass within 150 pc can be an unbiasedly constrained ensemble, with a scatter of ~0.255 dex. We show that the contraction of member stars in nearby systems is detectable based on Gaia DR3 proper motion errors. In the end, we discuss the effect of binary orbital motions upon dynamical modelings of ultra faint dwarfs. In particular, the inner densities are mostly deflated due to the negative gradients in the velocity dispersion profiles, rather than inflated in the traditional recognition.
