Radio Follow-Up of a Candidate gamma-Ray Transient in the Sky Localization Area of GW170608
Journal Article - Open Access
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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After the identification of a candidate gamma-ray transient in the error region of the binary black hole BBH merger GW150914 by the Fermi satellite, the question of whether BBH mergers can be associated with electromagnetic counterparts remains highly debated. Here, we present radio follow-up observations of GW170608, a BBH merger that occurred during the second observing run O2 of the Advanced Laser Interferometer Gravitational-wave Observatory LIGO. Our radio follow-up focused on a specific field contained in the GW170608 sky localization area, where a candidate high-energy transient was detected by the Fermi Large Area Telescope LAT. We make use of data collected at 1.4 GHz with the Karl G. Jansky Very Large Array VLA, as well as with the VLA Low-band Ionosphere and Transient Experiment VLITE. Our analysis is sensitive to potential radio afterglows with luminosity densities L sub 1.4GHz or 6 1028 erg sexp-1 Hzexp -1. In the most optimistic theoretical models, approx. 20 of BBH events occurring in massive hosts could be associated with outflows as radio luminous as this. Although we find no evidence for the presence of a radio counterpart associated with the LAT candidate in the GW170608 error region, our analysis demonstrates the feasibility of future radio follow-up observations of well-localized BBHs. Comparing our radio upper limits with theoretical expectations for the radio afterglows potentially associated with jets launched in BBH mergers, we find that for jets of energy approx. 10 exp 49 erg seen on-axis, only jet angles Theta sub jet approx. 40 deg. are compatible with the observations.
- Radiofrequency Wave Propagation
- Optical Detection and Detectors