GCN Circular 24250
Subject
LIGO/Virgo S190426c: a possible lensed NS-NS merger
Date
2019-04-26T21:27:30Z (6 years ago)
From
Graham P Smith at U of Birmingham <gps@star.sr.bham.ac.uk>
G. P. Smith (Birmingham), M. Bianconi (Birmingham), R. Massey (Durham),
and A. Robertson (Durham) report on behalf of the Gravitationally Lensed
Gravitational Wave Hunters
The non-zero value of Prob_MassGap identifies S190426c (GCN24237) as a
possible strongly-lensed NS-NS merger - i.e. its true redshift and
luminosity distance may be larger, and true mass may be smaller than
inferred by LIGO/Virgo. The rate of such detections is predicted to be
~0.01 per Earth year during O3.
The putative lens could be an individual galaxy, or a group/cluster of
galaxies. None of the 130 known strong-lensing clusters in the sample
discussed by Smith et al. (2018) are located in the updated 90% credible
sky localization released an hour after detection and stated as the
currently preferred skymap in GCN24237.
At the estimated luminosity distance to the source (D_L~375Mpc;
GCN24237) an AT2017gfo-like counterpart would have an apparent B/V-band
magnitude of AB<~24.5 within ~2 days of the LIGO/Virgo detection. This
estimate (albeit redshifted in to the i-band, and time-dilated to ~4
days post-detection) is also valid if the source is strongly-lensed and
actually at a redshift of z~1.
We encourage colleagues to observe the sky localization of this source
down to AB~25, to search for a kilonova-like counterpart, and thus
explore the possibility that this source is strongly-lensed, for example
by a massive galaxy or group of galaxies.
Background information on the details of this circular can be found in
these publications:
Smith, Jauzac, Veitch, et al., 2018, MNRAS, 475, 3823
Smith, Robertson, Bianconi, Jauzac, arXiv:1902.05140
Smith, Bianconi, Jauzac, et al., 2019, MNRAS, 485, 5180