A kilonova as the electromagnetic counterpart to a gravitational-wave source
Abstract
Gravitational waves were discovered with the detection of binary black hole mergers and they should also be detectable from lower mass neutron star mergers. These are predicted to eject material rich in heavy radioactive isotopes that can power an electromagnetic signal called a kilonova. The gravitational wave source GW170817 arose from a binary neutron star merger in the nearby Universe with a relatively well confined sky position and distance estimate. Here we report observations and physical modelling of a rapidly fading electromagnetic transient in the galaxy NGC4993, which is spatially coincident with GW170817 and a weak short gamma-ray burst. The transient has physical parameters broadly matching the theoretical predictions of blue kilonovae from neutron star mergers. The emitted electromagnetic radiation can be explained with an ejected mass of 0.04 +/- 0.01 Msol, with an opacity of kappa <= 0.5 cm2/gm at a velocity of 0.2 +/- 0.1c. The power source is constrained to have a power law slope of beta = -1.2 +/- 0.3, consistent with radioactive powering from r-process nuclides. We identify line features in the spectra that are consistent with light r-process elements (90 < A < 140). As it fades, the transient rapidly becomes red, and emission may have contribution by a higher opacity, lanthanide-rich ejecta component. This indicates that neutron star mergers produce gravitational waves, radioactively powered kilonovae, and are a nucleosynthetic source of the r-process elements.
Keywords
Cite
@article{arxiv.1710.05841,
title = {A kilonova as the electromagnetic counterpart to a gravitational-wave source},
author = {S. J. Smartt and T. -W. Chen and A. Jerkstrand and M. Coughlin and E. Kankare and S. A. Sim and M. Fraser and C. Inserra and K. Maguire and K. C. Chambers and M. E. Huber and T. Kruhler and G. Leloudas and M. Magee and L. J. Shingles and K. W. Smith and D. R. Young and J. Tonry and R. Kotak and A. Gal-Yam and J. D. Lyman and D. S. Homan and C. Agliozzo and J. P. Anderson and C. R. Angus C. Ashall and C. Barbarino and F. E. Bauer and M. Berton and M. T. Botticella and M. Bulla and J. Bulger and G. Cannizzaro and Z. Cano and R. Cartier and A. Cikota and P. Clark and A. De Cia and M. Della Valle and L. Denneau and M. Dennefeld and L. Dessart and G. Dimitriadis and N. Elias-Rosa and R. E. Firth and H. Flewelling and A. Flors and A. Franckowiak and C. Frohmaier and L. Galbany and S. Gonzalez-Gaitan and J. Greiner and M. Gromadzki and A. Nicuesa Guelbenzu and C. P. Gutierrez and A. Hamanowicz and L. Hanlon and J. Harmanen and K. E. Heintz and A. Heinze and M. -S. Hernandez and S. T. Hodgkin and I. M. Hook and L. Izzo and P. A. James and P. G. Jonker and W. E. Kerzendorf and S. Klose and Z. Kostrzewa-Rutkowska and M. Kowalski and M. Kromer and H. Kuncarayakti and A. Lawrence and T. B. Lowe and E. A. Magnier and I. Manulis and A. Martin-Carrillo and S. Mattila and O. McBrien and A. Muller and J. Nordin and D. O'Neill and F. Onori and J. T. Palmerio and A. Pastorello and F. Patat and G. Pignata and Ph. Podsiadlowski and M. L. Pumo and S. J. Prentice and A. Rau and A. Razza and A. Rest and T. Reynolds and R. Roy and A. J. Ruiter and K. A. Rybicki and L. Salmon and P. Schady and A. S. B. Schultz and T. Schweyer and I. R. Seitenzahl and M. Smith and J. Sollerman and B. Stalder and C. W. Stubbs and M. Sullivan and H. Szegedi and F. Taddia and S. Taubenberger and G. Terreran and B. van Soelen and J. Vos and R. J. Wainscoat and N. A. Walton and C. Waters and H. Weiland and M. Willman and P. Wiseman and D. E. Wright and L. Wyrzykowski and O. Yaron},
journal= {arXiv preprint arXiv:1710.05841},
year = {2017}
}
Comments
Nature, in press, DOI 10.1038/nature24303. Data files will be made available at http://www.pessto.org