Modeling intracluster gas in triaxial dark halos: An analytic approach

We present the first physical model for the nonspherical intracluster gas distribution in hydrostatic equilibrium under the gravity of triaxial dark matter halos. Adopting the concentric triaxial density profiles of dark halos with constant axis ratios proposed by Jing and Suto in 2002, we derive an analytical expression for the triaxial halo potential on the basis of perturbation theory and find the hydrostatic solutions for the gas density and temperature profiles in both isothermal and polytropic equations of state. The resulting isopotential surfaces are well approximated by triaxial ellipsoids with the eccentricities dependent on the radial distance. We also find a formula for the eccentricity ratio between the intracluster gas and the underlying dark halo. Our results allow one to determine the shapes of the underlying dark halos from the observed intracluster gas through X-ray and/or Sunyaev-Zeldovich effect clusters.