Observational evidence for extended emission to GW170817

Journal
Date Issued
2019
Author(s)
van Putten, Maurice H. P. M.
•
DOI
Abstract
The recent LIGO event GW170817 is the merger of a double neutron star system with an associated short GRB170817A with 2.9 ± 0.3 s soft emission over 8-70 keV. This association has a Gaussian equivalent level of confidence of 5.1σ. The merger produced a hypermassive neutron star or stellar mass black hole with prompt or continuous energy output powering GRB170817A. Here, we report on a possible detection of extended emission (EE) in gravitational radiation during GRB170817A: a descending chirp with characteristic time-scale τ_s=3.01± 0.2 s in a (H1,L1)-spectrogram up to 700 Hz with Gaussian equivalent level of confidence greater than 3.3σ based on causality alone following edge detection applied to (H1,L1)-spectrograms merged by frequency coincidences. Additional confidence derives from the strength of this EE. The observed frequencies below 1 kHz indicate a hypermassive magnetar rather than a black hole, spinning down by magnetic winds and interactions with dynamical mass ejecta.
Volume
482
Issue
1
Start page
L46
Uri
Url
Issn Identifier
0035-8711
Ads BibCode
2019MNRAS.482L..46V
Rights
open.access
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