MCMC chain of Milky Way gravitational potential models from McMillan (2017, MNRAS, 465, 76)

These are the full MCMC chains used for the main suite of results from McMillan (2017, MNRAS, 465, 76). Each line gives the parameters of a single model, with some of its derived properties, and an associated weight (the number of steps that the chain stayed at this model). The parameters are described in the README file, and further detail can be found in the original paper.

The disc density profiles are of the form

\(\begin{equation} \rho_d(R,z)=\left\{\begin{array}{lc}\frac{\Sigma(R)}{2z_d}\,\textrm{exp}\left(\frac{-\mid z\mid}{z_d}\right) & \textrm{for }z_d > 0 \\ \frac{\Sigma(R)}{4(-z_d)}\,\textrm{sech}^2\left(\frac{z}{2\,z_d}\right) & \textrm{for } z_d < 0,\\\end{array}\right. \end{equation}\)

where

\(\begin{equation} \Sigma(R)=\Sigma_0\;\textrm{exp}\left(-\frac{R_0}{R}-\frac{R}{R_d}+ \epsilon\textrm{cos}\left(\frac{\pi R}{R_d}\right)\right), \end{equation} \)

with parameters \(\Sigma_0, R_d, z_d, R_0, \epsilon\) (note that \(R_0\) here is not the position of the Sun, and that \(\epsilon\) is not used).

Spheroids have 

\(\begin{equation} \rho_s=\frac{\rho_0}{(r^\prime/r_0)^\gamma(1+r^\prime/r_0)^{\beta-\gamma}}\; \textrm{exp}\left[-\left(r^\prime/r_{cut}\right)^2\right], \end{equation} \)

where

\(\begin{equation} r^\prime = \sqrt{R^2 + (z/q)^2} \end{equation} \)

with parameters \( \rho_0, q, \gamma, \beta, r_0, r_{cut}\) (note that \(r_0\) is different again)