Accurate flux calibration of GW170817: is the X-ray counterpart on the rise?

Eleanora Troja, Brendan O'Connor, Geoffrey Scott Ryan, L. Piro, R. Ricci, Bing Zhang, Tsvi Piran, G. Bruni, S. B. Cenko, Hendrik Van Eerten

Research output: Contribution to journalArticlepeer-review


X-ray emission from the gravitational wave transient GW170817 is well described as non-thermal afterglow radiation produced by a structured relativistic jet viewed off-axis. We show that the X-ray counterpart continues to be detected at 3.3 years after the merger. Such long-lasting signal is not a prediction of the earlier jet models characterized by a narrow jet core and a viewing angle ≈20 deg, and is spurring a renewed interest in the origin of the X-ray emission. We present a comprehensive analysis of the X-ray dataset aimed at clarifying existing discrepancies in the literature, and in particular the presence of an X-ray rebrightening at late times. Our analysis does not find evidence for an increase in the X-ray flux, but confirms a growing tension between the observations and the jet model. Further observations at radio and X-ray wavelengths would be critical to break the degeneracy between models.

Original languageEnglish
Pages (from-to)1902-1909
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Early online date4 Dec 2021
Publication statusPublished - 28 Feb 2022


  • gamma-ray burst
  • gravitational waves
  • stars: neutron

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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