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The outflow structure of GW170817 from late-time broad-band observations

Troja, E. and Piro, L. and Ryan, G. and van Eerten, H. and Ricci, R. and Wieringa, M. and Lotti, S. and Sakamoto, T. and Cenko, S. B. (2018) The outflow structure of GW170817 from late-time broad-band observations. Monthly Notices of the Royal Astronomical Society: Letters, 478 (1). L18-L23. ISSN 1745-3925. doi:10.1093/mnrasl/sly061.

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We present our broad-band study of GW170817 from radio to hard X-rays, including NuSTAR and Chandra observations up to 165  d after the merger, and a multimessenger analysis including LIGO constraints. The data are compared with predictions from a wide range of models, providing the first detailed comparison between non-trivial cocoon and jet models. Homogeneous and power-law shaped jets, as well as simple cocoon models are ruled out by the data, while both a Gaussian shaped jet and a cocoon with energy injection can describe the current data set for a reasonable range of physical parameters, consistent with the typical values derived from short GRB afterglows. We propose that these models can be unambiguously discriminated by future observations measuring the post-peak behaviour, with F_ν ∝ t^(∼−1.0) for the cocoon and F_ν∝ t^(∼−2.5) for the jet model.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Troja, E.0000-0002-1869-7817
Lotti, S.0000-0002-3088-1561
Cenko, S. B.0000-0003-1673-970X
Alternate Title:The outflow structure of GW170817 from late time broadband observations
Additional Information:© The Author(s) 2018. Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. Accepted 2018 April 4. Received 2018 March 19; in original form 2018 January 18. Published: 13 April 2018. For their support to these observations we thank B. Wilkes and the Chandra staff, J. Stevens and the CSIRO staff. Support for this work was partially provided by the National Aeronautics and Space Administration through grants issued by the Chandra X-ray Observatory Center and by the Space Telescope Science Insitute. This work was partially supported by the European Union Horizon 2020 Programme under the AHEAD project.
Subject Keywords:gravitational waves – gamma-ray burst: general – gamma-ray burst.
Issue or Number:1
Record Number:CaltechAUTHORS:20180123-131751240
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Official Citation:E Troja, L Piro, G Ryan, H van Eerten, R Ricci, M H Wieringa, S Lotti, T Sakamoto, S B Cenko; The outflow structure of GW170817 from late-time broad-band observations, Monthly Notices of the Royal Astronomical Society: Letters, Volume 478, Issue 1, 21 July 2018, Pages L18–L23,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84480
Deposited By: Joy Painter
Deposited On:01 Feb 2018 00:33
Last Modified:15 Nov 2021 20:20

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