Search for resonances decaying to photon pairs in 139 $fb^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector.

Searches for new resonances in the diphoton final state, with spin-0 as predicted by theories with an extended Higgs sector and with spin-2 using a warped extra-dimension benchmark model, are presented using 139 fb$^{-1}$ of $\sqrt{s} =$ 13TeV $pp$ collision data collected the ATLAS experiment at the LHC. No significant deviation from the Standard Model is observed and upper limits are placed on the production cross-section times branching ratio to two photons as a function of the resonance mass.