Production of electroweak bosons in Pb+Pb, $p$+Pb and $pp$ collisions with the ATLAS detector

Electroweak bosons produced in ultrarelativistic heavy-ion collisions serve as excellent probes of the collision geometry and centrality. Their production rates should be unaffected by initial-state effects. Due to the correlation between the kinematics of quarks from incoming nuclei and the rapidity of produced electroweak bosons, they also provide insight into nuclear modifications of parton distribution functions (PDFs). This talk presents the latest ATLAS results on massive electroweak boson production in Pb+Pb and $pp$ collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV using data collected by the ATLAS experiment in 2015. The yields of $W$ and $Z$ bosons produced per inelastic Pb+Pb collision are compared to cross-sections measured in $pp$ collisions and used to construct nuclear modification factors. A comparison of the measured yields and cross-sections to calculations obtained with various (nuclear) PDF sets is also presented. This talk also summarizes selected results on photon production in $p$+Pb collisions.