Hydrodynamical attractor and thermal particle production in heavy-ion collision

Study of thermal particle production is crucial to understand the space-time evolution of the fireball produced in high energy heavy-ion collisions. We consider thermal particle production within the framework of relativistic viscous hydrodynamics and employ recently obtained analytical solutions of higher-order viscous hydrodynamics with longitudinal Bjorken expansion to calculate the spectra of dileptons and photons. Using these analytical solutions, we constrain the allowed initial states by demanding positivity and reality of energy density throughout the evolution. Further, we compute thermal particle spectra and study the particle yield in context of hydrodynamic attractors. We find that, of all allowed solutions, the evolution corresponding to attractor solution leads to maximum production of thermal particles.