of the classical anisotropy parameter $\beta(r)$ are nearly identical in core galaxies. Moreover, they match quantitatively the predictions of black hole binary simulations, providing the first convincing dynamical evidence for core scouring in the most massive elliptical galaxies.'
author:
- 'J. Thomas, R. P. Saglia, R. Bender, P. Erwin, and M. Fabricius'
title: The dynamical fingerprint of core scouring in massive elliptical galaxies
---

Introduction
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Elliptical galaxies have long been believed to be the end-product of collisions, or mergers, between galaxies. Tracing back in time the evolutionary history of individual ellipticals is difficult, however, since galaxy collisions involve strong distortions in the gravitational potential that randomize the distribution of stellar orbits. Most of the information about the structure of possible progenitor galaxies and even the number of mergers is therefore erased. For example, over several orders of magnitude in radius, the smooth light profiles of elliptical galaxies can be well described by the single three-parameter S[é]{}rsic function [@Sersic63; @Caon93]. However, the most massive galaxies often exhibit surface brightness profiles that are, interior to a “break” or “core” radius ${r_b}$, significantly flatter than the inward extrapolation of the outer, S[é]{}rsic-like profile. The resulting cores have typical sizes of ${r_b}\sim 50-500 