2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/6818I review constraints on the radial density profiles and ellipticities of the dark matter obtained from recent X-ray observations with Chandra and XMM of elliptical galaxies and galaxy clusters and discuss their implications, especially for the self-interacting dark matter model.10 pages, 4 figures, Invited review to appear in the proceedings of the IAU Symposium 220: "Dark matter in galaxies", eds. S. Ryder, D.J. Pisano, M. Walker and K. Freeman, Sydney, July 2003, to be published in the ASP conference seriesAstrophysicstext