Swift and NuSTAR observations of GW170817: Detection of a blue kilonova

P A Evans; S B Cenko; J A Kennea; S W K Emery; N P M Kuin; O Korobkin; R T Wollaeger; C L Fryer; K K Madsen; F A Harrison; Y Xu; E Nakar; K Hotokezaka; A Lien; S Campana; S R Oates; E Troja; A A Breeveld; F E Marshall; S D Barthelmy; A P Beardmore; D N Burrows; G Cusumano; A D'Aì; P D'Avanzo; V D'Elia; M de Pasquale; W P Even; C J Fontes; K Forster; J Garcia; P Giommi; B Grefenstette; C Gronwall; D H Hartmann; M Heida; A L Hungerford; M M Kasliwal; H A Krimm; A J Levan; D Malesani; A Melandri; H Miyasaka; J A Nousek; P T O'Brien; J P Osborne; C Pagani; K L Page; D M Palmer; M Perri; S Pike; J L Racusin; S Rosswog; M H Siegel; T Sakamoto; B Sbarufatti; G Tagliaferri; N R Tanvir; A Tohuvavohu

doi:10.1126/science.aap9580

Swift and NuSTAR observations of GW170817: Detection of a blue kilonova

Science. 2017 Dec 22;358(6370):1565-1570. doi: 10.1126/science.aap9580. Epub 2017 Oct 16.

Authors

P A Evans¹, S B Cenko^{2

3}, J A Kennea⁴, S W K Emery⁵, N P M Kuin⁵, O Korobkin⁶, R T Wollaeger⁶, C L Fryer⁶, K K Madsen⁷, F A Harrison⁷, Y Xu⁷, E Nakar⁸, K Hotokezaka⁹, A Lien^{10

11}, S Campana¹², S R Oates¹³, E Troja^{2

14}, A A Breeveld⁵, F E Marshall², S D Barthelmy², A P Beardmore¹⁵, D N Burrows⁴, G Cusumano¹⁶, A D'Aì¹⁶, P D'Avanzo¹², V D'Elia^{17

18}, M de Pasquale¹⁹, W P Even^{6

20}, C J Fontes⁶, K Forster⁷, J Garcia⁷, P Giommi¹⁸, B Grefenstette⁷, C Gronwall^{4

21}, D H Hartmann²², M Heida⁷, A L Hungerford⁶, M M Kasliwal²³, H A Krimm^{24

25}, A J Levan¹³, D Malesani²⁶, A Melandri¹², H Miyasaka⁷, J A Nousek⁴, P T O'Brien¹⁵, J P Osborne¹⁵, C Pagani¹⁵, K L Page¹⁵, D M Palmer²⁷, M Perri^{17

18}, S Pike⁷, J L Racusin², S Rosswog²⁸, M H Siegel⁴, T Sakamoto²⁹, B Sbarufatti⁴, G Tagliaferri¹², N R Tanvir¹⁵, A Tohuvavohu⁴

Affiliations

¹ University of Leicester, X-ray and Observational Astronomy Research Group, Leicester Institute for Space and Earth Observation, Department of Physics and Astronomy, University Road, Leicester LE1 7RH, UK. [email protected].
² Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
³ Joint Space-Science Institute, University of Maryland, College Park, MD 20742, USA.
⁴ Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802, USA.
⁵ University College London, Mullard Space Science Laboratory, Holmbury St. Mary, Dorking RH5 6NT, UK.
⁶ Center for Theoretical Astrophysics, Los Alamos National Laboratory, Los Alamos, NM 87545 USA.
⁷ Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
⁸ The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel.
⁹ Center for Computational Astrophysics, Simons Foundation, 162 5th Avenue, New York, NY 10010, USA.
¹⁰ Center for Research and Exploration in Space Science and Technology (CRESST) and NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
¹¹ Department of Physics, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
¹² Istituto Nazionale di Astrofisica (INAF)-Osservatorio Astronomico di Brera, Via Bianchi 46, I-23807 Merate, Italy.
¹³ Department of Physics, University of Warwick, Coventry CV4 7AL, UK.
¹⁴ Department of Physics and Astronomy, University of Maryland, College Park, MD 20742-4111, USA.
¹⁵ University of Leicester, X-ray and Observational Astronomy Research Group, Leicester Institute for Space and Earth Observation, Department of Physics and Astronomy, University Road, Leicester LE1 7RH, UK.
¹⁶ INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Palermo, via Ugo La Malfa 153, I-90146, Palermo, Italy.
¹⁷ INAF-Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone, Italy.
¹⁸ Space Science Data Center-Agenzia Spaziale Italiana (ASI), I-00133 Roma, Italy.
¹⁹ Department of Astronomy and Space Sciences, University of Istanbul, Beyzt 34119, Istanbul, Turkey.
²⁰ Department of Physical Sciences, Southern Utah University, Cedar City, UT 84720, USA.
²¹ Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802, USA.
²² Kinard Lab of Physics, Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978, USA.
²³ Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA.
²⁴ Universities Space Research Association, 7178 Columbia Gateway Drive, Columbia, MD 21046, USA.
²⁵ National Science Foundation, 2415 Eisenhower Avenue, Alexandria, VA 22314, USA.
²⁶ Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø, Denmark.
²⁷ Los Alamos National Laboratory, B244, Los Alamos, NM 87545, USA.
²⁸ The Oskar Klein Centre, Department of Astronomy, AlbaNova, Stockholm University, SE-106 91 Stockholm, Sweden.
²⁹ Department of Physics and Mathematics, Aoyama Gakuin University, Sagamihara, Kanagawa, 252-5258, Japan.

PMID: 29038371
DOI: 10.1126/science.aap9580

Abstract

With the first direct detection of merging black holes in 2015, the era of gravitational wave (GW) astrophysics began. A complete picture of compact object mergers, however, requires the detection of an electromagnetic (EM) counterpart. We report ultraviolet (UV) and x-ray observations by Swift and the Nuclear Spectroscopic Telescope Array of the EM counterpart of the binary neutron star merger GW170817. The bright, rapidly fading UV emission indicates a high mass (≈0.03 solar masses) wind-driven outflow with moderate electron fraction (Y_e ≈ 0.27). Combined with the x-ray limits, we favor an observer viewing angle of ≈30° away from the orbital rotation axis, which avoids both obscuration from the heaviest elements in the orbital plane and a direct view of any ultrarelativistic, highly collimated ejecta (a γ-ray burst afterglow).

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Grants and funding

European Research Council/International