[vsnet-grb-info 25084] LIGO/Virgo S200224ca: Identification of a GW compact binary merger candidate The LIGO Scientific Collaboration and the Virgo Collaboration

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27184
SUBJECT: LIGO/Virgo S200224ca: Identification of a GW compact binary merger candidate The LIGO Scientific Collaboration and the Virgo Collaboration
DATE:    20/02/24 22:53:00 GMT
FROM:    Vinaya Valsan at U. of Wisconsin Milwaukee  <vvalsan at uwm.edu>

We identified the compact binary merger candidate S200224ca during

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

Livingston Observatory (L1), and Virgo Observatory (V1) at 2020-02-24

22:22:34.406 UTC (GPS time: 1266618172.406). The candidate was found

by the PyCBC Live [1], CWB [2], GstLAL [3], MBTAOnline [4] ,and SPIIR [5]

analysis pipelines.


S200224ca is an event of interest because its false alarm rate, as

estimated by the online analysis, is 1.6e-11 Hz, or about one in 1e3

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

https://gracedb.ligo.org/superevents/S200224ca


The classification of the GW signal, in order of descending

probability, is BBH (>99%), Terrestrial (<1%), 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

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

event time.

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

[6], distributed via GCN notice about 10 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 well fit by an

ellipse with an area of 73 deg2 described by the following DS9 region

(right ascension, declination, semi-major axis, semi-minor axis,

position angle of the semi-minor axis):

   icrs; ellipse(11h38m42s, -09d20m21s, 9d, 3d, 68d)

Marginalized over the whole sky, the a posteriori luminosity distance

estimate is 1585 +/- 331 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] Messick et al. PRD 95, 042001 (2017)

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

 [5] Qi Chu, PhD Thesis, The University of Western Australia (2017)

 [6] Singer & Price PRD 93, 024013 (2016) [7] Singer & Price PRD 93,

024013 (2016)