[vsnet-grb-info 25877] LIGO/Virgo MS200614ct: Identification of a test binary black hole candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27977
SUBJECT: LIGO/Virgo MS200614ct: Identification of a test binary black hole candidate
DATE:    20/06/18 04:11:20 GMT
FROM:    Surabhi Sachdev at LVC  <surabhi.sachdev at gmail.com>

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 MS200614ct during

real-time processing of data from LIGO Hanford Observatory (H1), LIGO

Livingston Observatory (L1), and Virgo Observatory (V1) at 2020-06-14

15:30:50.363 UTC (GPS time: 1276183868.363). The candidate was found

by the MBTAOnline [1], CWB [2], PyCBC Live [3], and GstLAL [4]

analysis pipelines.


MS200614ct is an event of interest because its false alarm rate, as

estimated by the online analysis, is 9.1e-09 Hz, or about one in 3

years. The event's properties can be found at this URL:

https://gracedb.ligo.org/superevents/MS200614ct


The classification of the GW signal, in order of descending

probability, is BBH (97%), Terrestrial (3%), BNS (<1%), NSBH (<1%), or

MassGap (<1%).


Assuming the candidate is astrophysical in origin, the probability

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

<1% [6]. Using the masses and spins inferred from the signal, the

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

<1% [6].


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

[5],

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

[5].


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 841 deg2.

Marginalized over the whole sky, the a posteriori luminosity distance

estimate is 1998 +/- 526 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] Adams et al. CQG 33, 175012 (2016)

 [2] Klimenko et al. PRD 93, 042004 (2016)

 [3] Nitz et al. PRD 98, 024050 (2018)

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

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

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