TITLE: GCN CIRCULAR NUMBER: 36794 SUBJECT: LIGO/Virgo/KAGRA S240630t: Identification of a GW compact binary merger candidate DATE: 24/06/30 11:17:00 GMT FROM: eporcell@nikhef.nl
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:
We identified the compact binary merger candidate S240630t during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2024-06-30 10:17:03.372 UTC (GPS time: 1403777841.372). The candidate was found by the CWB [1], GstLAL [2], and PyCBC Live [3] analysis pipelines.
S240630t is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.9e-12 Hz, or about one in 1e4 years. The event's properties can be found at this URL:
https://gracedb.ligo.org/superevents/S240630t
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%. [4] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [4] 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%.
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 [5], distributed via GCN notice about 23 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [5], 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 1033 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 3026 +/- 834 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/.
[1] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [2] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. (2023) arXiv:2305.05625 [3] Dal Canton et al. ApJ 923, 254 (2021) doi:10.3847/1538-4357/ac2f9a [4] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [5] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013
View this GCN Circular online at https://gcn.nasa.gov/circulars/36794. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...