Probing Dark Matter's Gravitational Effects Locally with TianQin

Abstract: In this study, we explore the potential of using TianQin missions to probe the local gravitational effects of dark matter. The TianQin project plans to launch satellites at both low and high orbits. High-precision orbit determination is expected to assist in the Earth's gravity or gravitational waves detection. By comparing the derived masses in low and high orbits, it is possible to constrain the amount of dark matter between the two spheres, hence placing a local constraint on dark matter's gravity effect. Our results show the capability of TianQin in detecting the density of dark matter around Earth, with an ultimate sensitivity to a value of $10^{-8}\,\,{\rm kg\,\,m^{-3}}$. This detection limit surpasses the estimated bounds for the solar system and the observation results for our Galaxy by approximately 7 and 14 orders of magnitude, respectively.