Photons at RHIC: The role of viscosity and of initial state fluctuations

TL;DR

This paper investigates the production and azimuthal anisotropy of real photons in heavy ion collisions at RHIC, emphasizing the effects of viscosity and initial state fluctuations through comprehensive 3D hydrodynamic modeling.

Contribution

It provides a detailed analysis of photon spectra and anisotropy considering various sources, initial conditions, and viscous effects in a full 3D hydrodynamic framework.

Findings

Viscous effects modify photon v_2 significantly.

Initial state fluctuations impact photon anisotropy.

Photon spectra depend on source interplay and evolution.

Abstract

We study real photons produced in heavy ion collisions at RHIC, and we calculate their spectrum and its azimuthal momentum anisotropy. The photons from a variety of sources are included, and the interplay and the time-evolution of those sources are modelled in a full 3D hydrodynamic simulation. We quantify the v_2 of thermal photons produced in ideal and viscous fluids, and the consequences of using different initial conditions are explored.