{
"subject": "LIGO/Virgo/KAGRA S230904n: Identification of a GW compact binary merger candidate",
"submittedHow": "web",
"bibcode": "2023GCN.34612....1L",
"createdOn": 1693807322967,
"circularId": 34612,
"submitter": "Luca Baiotti at Osaka University ",
"body": "The LIGO Scientific Collaboration, the Virgo Collaboration, and the\nKAGRA Collaboration report:\n\nWe identified the compact binary merger candidate S230904n during\nreal-time processing of data from LIGO Hanford Observatory (H1) and\nLIGO Livingston Observatory (L1) at 2023-09-04 05:10:13.128 UTC (GPS\ntime: 1377839431.128). The candidate was found by the GstLAL [1], MBTA\n[2], PyCBC Live [3], and SPIIR [4] analysis pipelines.\n\nS230904n is an event of interest because its false alarm rate, as\nestimated by the online analysis, is 2.2e-09 Hz, or about one in 14\nyears. The event's properties can be found at this URL:\n\nhttps://gracedb.ligo.org/superevents/S230904n\n\nThe classification of the GW signal, in order of descending\nprobability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS\n(<1%).\n\nAssuming the candidate is astrophysical in origin, the probability\nthat the lighter compact object is consistent with a neutron star mass\n(HasNS) is <1%. [5] Using the masses and spins inferred from the\nsignal, the probability of matter outside the final compact object\n(HasRemnant) is <1%. [5] Both HasNS and HasRemnant consider the\nsupport of several neutron star equations of state. The probability\nthat either of the binary components lies between 3 and 5 solar masses\n(HasMassgap) is 6%.\n\nTwo sky maps are available at this time and can be retrieved from the\nGraceDB event page:\n * bayestar.multiorder.fits,1, an initial localization generated by\nBAYESTAR [6], distributed via GCN notice about 31 seconds after the\ncandidate event time.\n * bayestar.multiorder.fits,2, an initial localization generated by\nBAYESTAR [6], distributed via GCN notice about 5 minutes after the\ncandidate event time.\n\nThe preferred sky map at this time is bayestar.multiorder.fits,2. For\nthe bayestar.multiorder.fits,2 sky map, the 90% credible region is\n1858 deg2. Marginalized over the whole sky, the a posteriori\nluminosity distance estimate is 1205 +/- 375 Mpc (a posteriori mean\n+/- standard deviation).\n\nFor further information about analysis methodology and the contents of\nthis alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide\nhttps://emfollow.docs.ligo.org/userguide/.\n\n [1] Tsukada et al. arXiv:2305.06286 (2023) and Ewing et al.\narXiv:2305.05625 (2023)\n [2] Aubin et al. CQG 38, 095004 (2021)\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"
}