Elliptic flow from thermal photons with magnetic field in holography

Abstract

We compute the elliptic flow $v_2$ of thermal photons in a strongly coupled plasma with constant magnetic field via gauge/gravity duality. The D3/D7 embedding is applied to generate the contributions from massive quarks. By considering the cases in 2+1 flavor SYM analogous to the photon production in QGP, we obtain the thermal-photon $v_2$, which is qualitatively consistent with the direct-photon $v_2$ measured in RHIC at intermediate energy. However, due to the simplified setup, the thermal-photon $v_2$ in our model should be regarded as the upper bound for the $v_2$ generated by solely magnetic field in the strongly coupled scenario.

Comments: 7 pages, 6 figures, paragraphs extended, journal version accepted by Physical Review D