The Local Dark Matter Density from SDSS-SEGUE G-dwarfs

Abstract

We derive the local dark matter density by applying the integrated Jeans equation method from Silverwood et al. (2016) to SDSS-SEGUE G-dwarf data processed and presented by Büdenbender et al. (2015). We use the MultiNest Bayesian nested sampling software to fit a model for the baryon distribution, dark matter and tracer stars, including a model for the 'tilt term' that couples the vertical and radial motions, to the data. The $\alpha$-young population from Büdenbender et al. (2015) yields the most reliable result of ${\rho }_{\mathrm{DM}}=0.46_{-0.09}^{+0.07}{\mathrm{GeV}\mathrm{cm}}^{-3}=0.012_{-0.002}^{+0.001}{\mathrm{M}}_{\odot }{\mathrm{pc}}^{-3}$. Our analyses yield inconsistent results for the $\alpha$-young and $\alpha$-old data, pointing to problems in the tilt term and its modelling, the data itself, the assumption of a flat rotation curve, or the effects of disequilibria.

Comments: 17 pages, 10 figures, submitted to MNRAS