On August 17, 2017 LIGO/Virgo detected a binary neutron star via gravitational waves. We observed 70 sq-degrees in the LIGO/Virgo spatial localization with the DECam on the 4m Blanco telescope covering 80% of the final map. Our group independently discovered an optical counterpart in NGC 4993. We searched our entire imaged region: the object in NGC 4993 was the only viable candidate. Our observations of NGC4993 show complicated morphology but simple star formation history. Our x-ray and radio observations indicate an off-axis jet as afterglow. Our high-cadence optical and infrared spectra show a source that must be described by at least two components, one of which is dominated by the r-process nucleosynthesis elements characteristic of a kilonova. Our modeling of the light curve demonstrates such a model in which 0.05 MO of material is ejected from the system. Finally, we discuss the first standard siren measurement of H0.
Publication Source (Journal or Book title)
Proceedings of the International Astronomical Union
Annis, J., González, G., & Hynes, R. (2017). Observations of GW170817 by DESGW and the DECam GW-EM Collaboration. Proceedings of the International Astronomical Union, 13 (S338), 72-79. https://doi.org/10.1017/S1743921318000935