[vsnet-grb-info 24807] LIGO/Virgo S200128d: Identification of a GW compact binary merger candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26906
SUBJECT: LIGO/Virgo S200128d: Identification of a GW compact binary merger candidate
DATE:    20/01/28 02:56:16 GMT
FROM:    Erik Katsavounidis at MIT  <kats at ligo.mit.edu>

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S200128d during

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

LIGO Livingston Observatory (L1) at 2020-01-28 02:20:11.903 UTC (GPS

time: 1264213229.903). The candidate was found by the PyCBC Live [1],

CWB [2], MBTAOnline [3], and GstLAL [4] analysis pipelines.


S200128d is an event of interest because its false alarm rate, as

estimated by the online analysis, is 1.6e-08 Hz, or about one in 1

year, 11 months. The event's properties can be found at this URL:

https://gracedb.ligo.org/superevents/S200128d


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%. Using the masses and spins inferred from the signal, the

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

<1%.


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], distributed via GCN notice about 3 minutes after the candidate

event time.

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

[5], distributed via GCN notice about 9 minutes after the candidate

event time.


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 2521 deg2.

Marginalized over the whole sky, the a posteriori luminosity distance

estimate is 4031 +/- 1241 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] Nitz et al. PRD 98, 024050 (2018)

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

[3] Adams et al. CQG 33, 175012 (2016)

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

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