The Sound of the Little Bangs

Abstract

Measurements of particles emitted from collisions of heavy ions at relativistic energies show evidence for temperature-fluctuations on the freeze-out surface of the expanding fireball. These can be understood as remnants of the density inhomogeneities in the initial collision overlap region. In this paper we present an analysis of heavy-ion collisions analogous to the analysis of the cosmic microwave background radiation. We use data on transverse momentum correlations to extract a power-spectrum from heavy-ion collisions and use a Glauber model for eccentricity to extract the transfer function needed to produce the observed correlations. We also discuss the acoustic signal, the sound that an observer inside the matter would hear.