Optical superluminal motion measurement in the neutron-star merger GW170817
- Creators
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Mooley, Kunal P.
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Anderson, Jay
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Lu, Wenbin
Abstract
The afterglow of the binary neutron-star merger GW1708171 gave evidence for a structured relativistic jet and a link between such mergers and short gamma-ray bursts. Superluminal motion, found using radio very long baseline interferometry (VLBI), together with the afterglow light curve provided constraints on the viewing angle (14–28 degrees), the opening angle of the jet core (less than 5 degrees) and a modest limit on the initial Lorentz factor of the jet core (more than 4). Here we report on another superluminal motion measurement, at seven times the speed of light, leveraging Hubble Space Telescope precision astrometry and previous radio VLBI data for GW170817. We thereby obtain a measurement of the Lorentz factor of the wing of the structured jet, as well as substantially improved constraints on the viewing angle (19–25 degrees) and the initial Lorentz factor of the jet core (more than 40).
Additional Information
We thank A. Deller for pointing out the required correction for radio VLBI positions, for reading of the manuscript and for providing comments. K.P.M. thanks A. Krone-Martins for discussions, D. Frail for commenting on an early version of this manuscript and Y. Mooley for help with the Nature submission. K.P.M. is indebted to K. Gaura-Nitay for providing the impetus to execute this project. This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with HST programmes GO-14771, GO-14804 and GO-15329. K.P.M. was a Jansky Fellow of the National Radio Astronomy Observatory and his work is currently supported through the National Research Foundation Grant AST-1911199. W.L. was supported by the David and Ellen Lee Fellowship at Caltech and Lyman Spitzer, Jr Fellowship at Princeton University.Additional details
- Eprint ID
- 117856
- Resolver ID
- CaltechAUTHORS:20221114-805047300.8
- NAS 5-26555
- NASA
- National Radio Astronomy Observatory
- AST-1911199
- NSF
- David and Ellen Lee Postdoctoral Scholarship
- Princeton University
- Created
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2022-11-29Created from EPrint's datestamp field
- Updated
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2023-01-19Created from EPrint's last_modified field
- Caltech groups
- TAPIR, Walter Burke Institute for Theoretical Physics