Elliptic flow of thermal photons at midrapidity in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV

TL;DR

This paper predicts the elliptic flow of thermal photons in gold-gold collisions at high energy using 3D ideal hydrodynamics, highlighting how flow asymmetry and transverse flow influence photon flow patterns.

Contribution

It provides the first detailed prediction of thermal photon elliptic flow at RHIC energies using 3D hydrodynamic modeling.

Findings

Maximum $v_2$ at $p_T \, \sim 2$ GeV/c

$v_2$ peaks at about 50% centrality

$v_2$ sensitive to lower $p_T$ integration limit

Abstract

The elliptic flow $v_{2}$ of thermal photons at midrapidity in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV is predicted, based on three-dimensional ideal hydrodynamics. Because of the interplay between the asymmetry and the strength of the transverse flow, the thermal photon $v_{2}$ reaches a maximum at $\pt \sim $ 2GeV/$c$ and the $\pt$-integrated $v_{2}$ reaches a maximum at about 50% centrality. The $\pt$-integrated $v_{2}$ is very sensitive to the lower limit of the integral but not sensitive to the upper limit due to the rapid decrease in the spectrum of the transverse momentum.