Measuring the mass profile of galaxy clusters beyond their virial radius
Abstract
Description
Traditional estimators of the mass of galaxy clusters assume that the cluster components (galaxies, intracluster medium, and dark matter) are in dynamical equilibrium. Two additional estimators, that do not require this assumption, were proposed in the 1990s: gravitational lensing and the caustic technique. With these methods, we can measure the cluster mass within radii much larger than the virial radius. In the caustic technique, the mass measurement is only based on the celestial coordinates and redshifts of the galaxies in the cluster field of view; therefore, unlike lensing, it can be, in principle, applied to clusters at any redshift. Here, we review the origin, the basics and the performance of the caustic method.
Lecture given at the International School of Physics Enrico Fermi of the Societa' Italiana di Fisica, Course CLXXII - "Astrophysics of Galaxy Clusters", Varenna, July 2008, ed. by A. Cavaliere and Y. Rephaeli; 20 pages, 9 figures
Lecture given at the International School of Physics Enrico Fermi of the Societa' Italiana di Fisica, Course CLXXII - "Astrophysics of Galaxy Clusters", Varenna, July 2008, ed. by A. Cavaliere and Y. Rephaeli; 20 pages, 9 figures