The Paleoclimatic evidence for Strongly Interacting Dark Matter Present in the Galactic Disk

Abstract

Using a recent geochemical reconstruction of the Phanerozoic climate which exhibits a 32 Ma oscillation with a phase and the secondary modulation expected from the vertical the motion of the solar system perpendicular to the galactic plane (shaviv et al. 2014), we show that a kinematically cold strongly interacting disk dark matter (dDM) component is necessarily present in the disk. It has a local density $\rho_\mathrm{dDM} = 0.11 \pm 0.03$ M$_{\odot}/$pc$^3$. It is also consistent with the observed constraints on the total gravitating mass and the baryonic components, and it is the natural value borne from the Toomre stability criterion. It also has surface density $\Sigma_\mathrm{dDM} = 15 \pm 5$ M$_{\odot}/$pc$^2$ and a vertical velocity dispersion of $\sigma_{W} = 8.0 \pm 4.5$ km/s. A dense ("dinosaur killing") thin disk is ruled out. The "normal" halo dark matter (hDM) component should then have a local density $\rho_\mathrm{hDM} \lesssim 0.01$ M$_{\odot}/$pc$^3$. If the dDM component follows the baryons, its average density parameter is $\Omega_\mathrm{dDM} = 1.5 \pm 0.5\%$ and it comprises about 1/8 to 1/4 of Milky Way (MW) mass within the solar circle.