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We investigate the nucleosynthesis of heavy elements in the winds ejected byaccretion disks formed in neutron star mergers. We compute the elementformation in disk outflows from hypermassive neutron star (HMNS) remnants ofvariable lifetime, including the effect of angular momentum transport in thedisk evolution. We employ long-term axisymmetric hydrodynamic disk simulationsto model the ejecta, and compute r-process nucleosynthesis with tracerparticles using a nuclear reaction network containing $\sim 8000$ species. Wefind that the previously known strong correlation between HMNS lifetime,ejected mass, and average electron fraction in the outflow is directly relatedto the amount of neutrino irradiation on the disk, which dominates massejection at early times in the form of a neutrino-driven wind. Production oflanthanides and actinides saturates at short HMNS lifetimes ($\lesssim 10$ ms),with additional ejecta contributing to a blue optical kilonova component forlonger-lived HMNSs. We find good agreement between the abundances from the diskoutflow alone and the solar r-process distribution only for short HMNSlifetimes ($\lesssim 10$ ms). For longer lifetimes, the rare-earth and thirdr-process peaks are significantly under-produced compared to the solar pattern,requiring additional contributions from the dynamical ejecta. Thenucleosynthesis signature from a spinning black hole (BH) can only overlap withthat from a HMNS of moderate lifetime ($\lesssim 60$ ms). Finally, we show thatangular momentum transport not only contributes with a late-time outflowcomponent, but that it also enhances the neutrino-driven component by movingmaterial to shallower regions of the gravitational potential, in addition toproviding additional heating.

Signatures of hypermassive neutron star lifetimes on r-process nucleosynthesis in the disk ejecta from neutron star mergers