[vsnet-grb-info 24083] LIGO/Virgo S191105e: Identification of a GW compact binary merger candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26182
SUBJECT: LIGO/Virgo S191105e: Identification of a GW compact binary merger candidate
DATE:    19/11/06 18:24:36 GMT
FROM:    Leo Singer at GSFC  <leo.p.singer at nasa.gov>

The LIGO Scientific Collaboration and the Virgo Collaboration report:

We identified the compact binary merger candidate S191105e during
real-time processing of data from LIGO Hanford Observatory (H1), LIGO
Livingston Observatory (L1), and Virgo Observatory (V1) at 2019-11-05
14:35:21.933 UTC (GPS time: 1256999739.933). The candidate was found
by the PyCBC Live [1], SPIIR [2], and GstLAL [3] analysis pipelines.

The preliminary alert was delayed by approximately one day due to a
GraceDB authentication issue.

S191105e is an event of interest because its false alarm rate, as
estimated by the online analysis, is 2.3e-08 Hz, or about one in 1
year, 4 months. The event's properties can be found at this URL:

https://gracedb.ligo.org/superevents/S191105e

The classification of the GW signal, in order of descending
probability, is BBH (95%), Terrestrial (5%), BNS (<1%), NSBH (<1%), or
MassGap (<1%).

Assuming the candidate is astrophysical in origin, there is strong
evidence against the lighter compact object having a mass < 3 solar
masses (HasNS: <1%). Using the masses and spins inferred from the
signal, there is strong evidence against matter outside the final
compact object (HasRemnant: <1%).

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

* "bayestar.fits.gz,0", a preliminary localization generated by
  BAYESTAR [4] for an earlier trigger, not the current preferred
  event, and
* "bayestar.fits.gz,1", an initial localization generated by BAYESTAR [4].
  For the bayestar.fits.gz,1 sky map, the 90% credible region is 1297
  deg2. Marginalized over the whole sky, the a posteriori luminosity
  distance estimate is 1168 +/- 330 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] Qi Chu, PhD Thesis, The University of Western Australia (2017)
 [3] Messick et al. PRD 95, 042001 (2017)
 [4] Singer & Price PRD 93, 024013 (2016)