[vsnet-grb-info 25863] LIGO/Virgo MS200614bz: Test Identification of a binary neutron star candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27963
SUBJECT: LIGO/Virgo MS200614bz: Test Identification of a binary neutron star candidate
DATE:    20/06/16 12:09:06 GMT
FROM:    Surabhi Sachdev at LVC  <surabhi.sachdev at ligo.org>

The LIGO Scientific Collaboration and the Virgo Collaboration report:


*** This is a test of the Early Warning alert system resulting from
archival O3

data. Times and sky localizations are fictitious. ***


We identified the compact binary merger candidate MS200614bz during
real-time

processing of data from LIGO Hanford Observatory (H1), LIGO Livingston

Observatory (L1), and Virgo Observatory (V1) at 2020-06-14 12:57:27.027 UTC

(GPS time: 1276174665.027). The candidate was found by the GstLAL [1]
analysis

pipeline.


MS200614bz is an event of interest because its false alarm rate, as
estimated

by the online analysis, is 1.3e-08 Hz, or about one in 2 years. The event's

properties can be found at this URL:

https://gracedb.ligo.org/superevents/MS200614bz


The classification of the GW signal, in order of descending probability, is
BNS

(62%), Terrestrial (38%), NSBH (0%), BBH (0%), or MassGap (0%).


Assuming the candidate is astrophysical in origin, the probability that the

lighter compact object has a mass < 3 solar masses (HasNS) is

>99%  [3]. Using the masses and spins inferred from the signal, the

probability of matter outside the final compact object (HasRemnant) is

>99% [3].


Two sky maps are available at this time and can be retrieved from the
GraceDB

event page:

 * bayestar.fits.gz,0, an initial localization generated by BAYESTAR

[2],

 * bayestar.fits.gz,1, an initial localization generated by BAYESTAR

[2].


The preferred sky map at this time is bayestar.fits.gz,1. For the

bayestar.fits.gz,1 sky map, the 90% credible region is 4219 deg2.
Marginalized

over the whole sky, the a posteriori luminosity distance estimate is 278 +/-

134 Mpc (a posteriori mean +/- standard deviation).


For further information about analysis methodology and the contents of this

alert, refer to the LIGO/Virgo Public Alerts User Guide

<https://emfollow.docs.ligo.org/userguide/>.




[1] Messick et al. PRD 95, 042001 (2017)

[2] Singer & Price PRD 93, 024013 (2016)

[3] Chatterjee et al. The Astrophysical Journal 896, 1 (2020)