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

TL;DR

This paper estimates the local dark matter density using SDSS-SEGUE G-dwarf data and advanced Bayesian modeling, finding a value around 0.012 M_sun/pc^3, but noting inconsistencies between different stellar populations.

Contribution

It applies the integrated Jeans equation with Bayesian nested sampling to SDSS data, providing a refined local dark matter density estimate and highlighting modeling challenges.

Findings

Estimated dark matter density: 0.012 M_sun/pc^3

Inconsistent results between stellar populations

Identified issues in tilt term modeling and data assumptions

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 B\"udenbender 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 B\"udenbender et al. (2015) yields the most reliable result of $\rho_{\rm DM} = 0.46^{+0.07}_{-0.09}\, {{\rm GeV\, cm}^{-3}} = 0.012^{+0.001}_{-0.002}\, {{\rm M}_\odot \, {\rm pc}^{-3}}$. 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.