Scalar relics from the hot Big Bang

Abstract: In this Letter, we motivate the fact that couplings between a scalar field and the Standard Model with strengths $10^{-6}(m_\phi/{\rm eV})^{-1/4}$ relative to gravity yield the total measured cosmological dark matter abundance over a broad mass range of $10^{-12}$ to $10^{14}\ \rm{eV}$. Remarkably, this result holds with minimal sensitivity to whether the scalar couples to electrons, photons, hadrons, or other particles at laboratory energy scales, thereby linking fifth force experiments to the search for dark matter.