Tungsten versus Selenium as a potential source of kilonova nebular emission observed by Spitzer

• DOI: 10.1093/mnrasl/slac071
• Publication Date: 2022-07-29T08:39:39Z
• Authors: Kenta Hotokezaka; Masaomi Tanaka; Daiji Kato; Gediminas Gaigalas
• Keywords: Kilonova; Line (geometry); Spitzer Space Telescope; Very Large Telescope

ABSTRACT Infrared emission lines arising from transitions between fine structure levels of heavy elements are expected to produce kilonova nebular emission. For the in GW170817, strong at $4.5\, {\rm \mu m}$ late times was detected by Spitzer Space Telescope but no source $3.6\, m}$. This peculiar spectrum indicates that line emitters exist around and absence To model we prepare a list based on selection rules LS coupling experimentally calibrated energy NIST database. method enables generate synthetic spectra with accurate wavelengths. We find is sensitive abundance pattern whether or not first r-process peak included. In both cases, can match observed data, leading two possible interpretations. If abundant, Se iii dominates flux. otherwise, W Os iii, Rh Ce iv be main sources. Observing for future wider wavelength range provide more conclusive elemental identification.