LIGO/Virgo/KAGRA S230904n: Identification of a GW compact binary merger candidate
Abstract
We identified the compact binary merger candidate S230904n during realtime processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 20230904 05:10:13.128 UTC (GPS time: 1377839431.128). The candidate was found by the GstLAL [1], MBTA [2], PyCBC Live [3], and SPIIR [4] analysis pipelines. S230904n is an event of interest because its false alarm rate, as estimated by the online analysis, is 2.2e09 Hz, or about one in 14 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S230904n The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), 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%. [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 6%. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 31 seconds after the candidate event time. * bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [6], distributed via GCN notice about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,2. For the bayestar.multiorder.fits,2 sky map, the 90% credible region is 1858 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1205 +/ 375 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] Tsukada et al. arXiv:2305.06286 (2023) and Ewing et al. arXiv:2305.05625 (2023) [2] Aubin et al. CQG 38, 095004 (2021) [3] Dal Canton et al. ApJ 923, 254 (2021) [4] Chu et al. PRD 105, 024023 (2022) [5] Chatterjee et al. ApJ 896, 54 (2020) [6] Singer & Price PRD 93, 024013 (2016)
 Publication:

GRB Coordinates Network
 Pub Date:
 September 2023
 Bibcode:
 2023GCN.34612....1L