LIGO/Virgo/KAGRA S230822bm: Identification of a GW compact binary merger candidate
Abstract
We identified the compact binary merger candidate S230822bm during realtime processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 20230822 23:03:37.497 UTC (GPS time: 1376780635.497). The candidate was found by the CWB [1] and GstLAL [2] analysis pipelines. S230822bm is an event of interest because its false alarm rate, as estimated by the online analysis, is 2.6e08 Hz, or about one in 1 year, 2 months. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S230822bm The classification of the GW signal, in order of descending probability, is BBH (98%), Terrestrial (2%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [3] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [3] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is 4%. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [4], distributed via GCN notice about 27 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [4], distributed via GCN notice about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 4472 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 6854 +/ 2325 Mpc (a posteriori mean +/ standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/userguide/. [1] Klimenko et al. PRD 93, 042004 (2016) [2] Tsukada et al. arXiv:2305.06286 (2023) and Ewing et al. arXiv:2305.05625 (2023) [3] Chatterjee et al. ApJ 896, 54 (2020) [4] Singer & Price PRD 93, 024013 (2016)
 Publication:

GRB Coordinates Network
 Pub Date:
 August 2023
 Bibcode:
 2023GCN.34520....1L