Identifying gamma-ray burst remnants in nearby galaxies

We study the spectral signatures arising from cooling and recombination of an interstellar medium whose equilibrium state has been altered over simila r to 100 pc by the radiation of a gamma-ray burst (GRB) and its afterglow. We identify signatures in the line diagnostics that are indicative of a pho toionized GRB remnant which is less than or similar to 5 x 10(4) yr old. We estimate that at least a few such remnants should be detectable in the Vir go Cluster of galaxies. If the gamma-ray emission from GRBs is beamed to a fraction f(b) of their sky, then the expected number of Virgo remnants is l arger by a factor of f(b)(-1). Virgo remnants can be resolved with arcsecon d imaging and are likely to be center-filled using narrowband filters of hi gh-ionization lines (such as [O III] lambda 5007 or He II lambda 4686) and limb-brightened for low-ionization lines (such as [S II] lambda 6717). The nonrelativistic blast wave might be visible separately, since it does not r each the outer edge of these young photoionized remnants. The remnants shou ld show evidence for ionization cones if the prompt or afterglow UV emissio n from GRBs is beamed.