Co-existence of Gravity and Antigravity: The Unification of Dark Matter and Dark Energy

Original · EN

Massive gravity with second and fourth derivatives is shown to give both attractive and repulsive gravities. In contrast to the attractive gravity correlated with the energy-momentum tensor, the repulsive gravity is related to a fixed mass mₓ, which equals a spin-dependent factor fσ times the graviton mass. Therefore, particles with energy below mₓ are both dark matter and dark energy: Their overall gravity is attractive with normal matter but repulsive among themselves. Detailed analyses reveal that this unified dark scenario can properly account for the observed dark matter/energy phenomena: galaxy rotation curves, transition from early cosmic deceleration to recent acceleration; and naturally overcome other dark scenarios' difficulties: the substructure and cuspy core problems, the difference of dark halo distributions in galaxies and clusters, and the cosmic coincidence. Very interestingly, Dirac particles have fσ=1/√ 2, all bosonic matter particles have fσ=0, and the only exceptional boson is the graviton itself, which may have fσ>1.