1706.04981
Probing the shape and internal structure of dark matter halos with the halo-shear-shear three-point correlation function
Shirasaki, Yoshida
WL 3pt statistics are powerful probes of the structure of DM haloes. Propose to use the correlation of the positions of galaxies with the shapes of BG galaxy pairs, known as the halo-shear-shear correlation (HSSC), to measure the mean halo ellipticity and the abundance of sub halos in a statistical manner. Run high-resolution cosmo N-body sims and use the outputs to measure the HSSC for galaxy haloes and cluster halos. Non-spherical halos cause a characteristic azimuthal variation of the HSSC, and massive sub halos in the outer region near the viral radius contribute to ~10% of the HSSC amplitude. Develop an analytic model of the 3pt statistics and test its accuracy using the sim results. Then make forecast for constraining the internal structure of dark matter halos with future galaxy surveys. With 1000 galaxy groups with mass greater than 1e13.5 Msun/h, the average halo ellipticity can be measured with an accuracy of 10%. A spherical, smooth mass distribution can be ruled out at a ~5 sigma significance level. The existence of sub halos whose masses are in 1-10 % of the main halo mass can be detected with ~1e4 galaxies/clusters. Conclude that the HSSC provides valuable information on the structure of dark halos and hence on the nature of DM.
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