Measurement of anisotropy of dark matter velocity distribution using directional detection

Although the velocity distribution of dark matter is assumed to be generally isotropic, some studies have found that $\sim 25$% of the distribution can have anisotropic components. As the directional detection of dark matter is sensitive to both the recoil energy and direction of nuclear recoil, directional information can prove useful in measuring the distribution of dark matter. Using a Monte Carlo simulation based on the modeled directional detection of dark matter, we analyze the differences between isotropic and anisotropic distributions and show that the isotropic case can be rejected at a 90% confidence level if $O({10}^4)$ events can be obtained.