A Decline in the X-Ray through Radio Emission from GW170817 Continues to Support an Off-axis Structured Jet

K. D. Alexander, R. Margutti, P. K. Blanchard, W. Fong, E. Berger, A. Hajela, T. Eftekhari, R. Chornock, P. S. Cowperthwaite, D. Giannios, C. Guidorzi, A. Kathirgamaraju, A. Macfadyen, B. D. Metzger, M. Nicholl, L. Sironi, V. A. Villar, P. K.G. Williams, X. Xie, J. Zrake

Research output: Contribution to journalArticlepeer-review

85 Scopus citations

Abstract

We present new observations of the binary neutron star merger GW170817 at Δt ≈ 220-290 days post-merger, at radio (Karl G. Jansky Very Large Array; VLA), X-ray (Chandra X-ray Observatory), and optical (Hubble Space Telescope; HST) wavelengths. These observations provide the first evidence for a turnover in the X-ray light curve, mirroring a decline in the radio emission at 5σ significance. The radio-to-X-ray spectral energy distribution exhibits no evolution into the declining phase. Our full multi-wavelength data set is consistent with the predicted behavior of our previously published models of a successful structured jet expanding into a low-density circumbinary medium, but pure cocoon models with a choked jet cannot be ruled out. If future observations continue to track our predictions, we expect that the radio and X-ray emission will remain detectable until ∼1000 days post-merger.

Original languageEnglish (US)
Article numberL18
JournalAstrophysical Journal Letters
Volume863
Issue number2
DOIs
StatePublished - Aug 20 2018

Keywords

  • gravitational waves
  • relativistic processes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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