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Dobie et al. present results from a search for the radio counterpart
to the possible neutron star–black hole merger GW190814 with ASKAP.
They carried out 10 epochs of observation spanning 2–655 days
post-merger at a frequency of 944 MHz. Each observation covered 30
square degrees, equivalent to 87% of the event localisation. They
conducted an untargeted search for radio transients in the field, as
well as a targeted search for transients associated with known
galaxies. They find one radio transient, ASKAP J005022.3−230349, but
conclude that it is unlikely to be associated with the merger. They
use their observations to place constraints on the inclination angle
of the merger and the density of the surrounding environment by
comparing their non-detection to model predictions for radio emission
from compact binary coalescences. This survey is also the most
comprehensive widefield search (in terms of sensitivity and both areal
and temporal coverage) for radio transients to-date and they calculate
the radio transient surface density at 944 MHz.
The figure above shows ASKAP imaging of the localisation region of GW190814 at
234 (bottom right) and 260 (top left) days post-merger
with both footprints outlined in grey. The 50% (dashed) and 90% (solid)
contours for the initial and final gravitational wave location skymaps
are shown in red and blue respectively.
The paper will be published in Monthly Notices of the Royal Astronomical Society.
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