{
"subject": "LIGO/Virgo/KAGRA S231118d: Identification of a GW compact binary merger candidate",
"submittedHow": "web",
"bibcode": "2023GCN.35090....1L",
"createdOn": 1700272387227,
"circularId": 35090,
"submitter": "Yi-Ru Chen at NTHU ",
"body": "The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:\n\nWe identified the compact binary merger candidate S231118d during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2023-11-18 00:56:26.845 UTC (GPS time: 1384304204.845). The candidate was found by the CWB [1], GstLAL [2], PyCBC Live [3], and SPIIR [4] analysis pipelines.\n\nS231118d is an event of interest because its false alarm rate, as estimated by the online analysis, is 3.2e-10 Hz, or about one in 1e2 years. The event's properties can be found at this URL:\n\nhttps://gracedb.ligo.org/superevents/S231118d\n\nThe classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), or NSBH (<1%).\n\nAssuming the candidate is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [5] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [5] 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 <1%.\n\nTwo sky maps are available at this time and can be retrieved from the GraceDB event page:\n * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 26 seconds after the candidate event time.\n * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 5 minutes after the candidate event time.\n\nThe preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 1063 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2352 +/- 681 Mpc (a posteriori mean +/- standard deviation).\n\nFor 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/.\n\n [1] Klimenko et al. PRD 93, 042004 (2016)\n [2] Tsukada et al. PRD 108, 043004 (2023) and Ewing et al. arXiv:2305.05625 (2023)\n [3] Dal Canton et al. ApJ 923, 254 (2021)\n [4] Chu et al. PRD 105, 024023 (2022)\n [5] Chatterjee et al. ApJ 896, 54 (2020)\n [6] Singer & Price PRD 93, 024013 (2016)\n"
}