{
"subject": "LIGO/Virgo/KAGRA S230726a: Identification of a GW compact binary merger candidate",
"submittedHow": "web",
"bibcode": "2023GCN.34264....1L",
"createdOn": 1690335531096,
"circularId": 34264,
"submitter": "Andy C ",
"body": "The LIGO Scientific Collaboration, the Virgo Collaboration, and the\nKAGRA Collaboration report:\n\nWe identified the compact binary merger candidate S230726a during\nreal-time processing of data from LIGO Livingston Observatory (L1) at\n2023-07-26 00:29:40.060 UTC (GPS time: 1374366598.060). The candidate\nwas found by the GstLAL [1] analysis pipeline.\n\nS230726a is an event of interest because its false alarm rate, as\nestimated by the online analysis, is 3.8e-14 Hz, or about one in 1e6\nyears. The event's properties can be found at this URL:\n\nhttps://gracedb.ligo.org/superevents/S230726a\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%. [2] Using the masses and spins inferred from the\nsignal, the probability of matter outside the final compact object\n(HasRemnant) is <1%. [2] 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 <1%.\n\nTwo sky maps are available at this time and can be retrieved from the\nGraceDB event page:\n * bayestar.multiorder.fits,0, an initial localization generated by\nBAYESTAR [3], distributed via GCN notice about 30 seconds after the\ncandidate event time.\n * bayestar.multiorder.fits,1, an initial localization generated by\nBAYESTAR [3], distributed via GCN notice about 5 minutes after the\ncandidate event time.\n\nThe preferred sky map at this time is bayestar.multiorder.fits,1. For\nthe bayestar.multiorder.fits,1 sky map, the 90% credible region is\n24219 deg2. Marginalized over the whole sky, the a posteriori\nluminosity distance estimate is 2077 +/- 699 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] Chatterjee et al. ApJ 896, 54 (2020)\n [3] Singer & Price PRD 93, 024013 (2016)"
}