On the role of magnetic field in photon excess in heavy ion collisions

Synchrotron photon spectrum in heavy-ion collisions is computed taking into account the spatial and temporal structure of magnetic field. It is found that a significant fraction of photon excess in heavy-ion collisions in the region $k_\bot=1-3$GeV can be attributed to the synchrotron radiation. Azimuthal anisotropy of the synchrotron photon spectrum is characterized by the Fourier coefficients $v_2=4/7$ and $v_4=1/10$ that are independent of photon momentum and centrality.