UC Berkeley

Recently, an extension of the geodesic equations of motion using the Dark Energy length scale was proposed. Here, we apply this extension to analyzing the motion of test particles at the galactic scale and longer. A cosmological check of the extension is made using the observed rotational velocity curves and core sizes of 1,393 spiral galaxies. We derive the density profile of a model galaxy using this extension, and with it, we calculate σ 8 to be 0.73±0.12; this is within experimental error of the WMAP value of $${0.761_{-0.048}^{+0.049}}$$ . We then calculate R 200 to be 206±53 kpc, which is in reasonable agreement with observations.