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GCN Circular 34087

Subject
LIGO/Virgo/KAGRA S230627c: Updated Sky localization and EM Bright Classification
Date
2023-06-27T04:37:12Z (8 months ago)
From
jgolomb@caltech.edu
The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:

We have conducted further analysis of the LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) data around the time of the compact binary merger (CBC) candidate S230627c (GCN Circular 34086). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN Notice, is available for retrieval from the GraceDB event page:

https://gracedb.ligo.org/superevents/S230627c

Based on posterior support from parameter estimation [1], under the assumption that the candidate S230627c is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [2] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [2] Both HasNS and HasRemnant consider the support of several neutron star equations of state. The probability that any one of the binary components lie between 3 to 5 solar mass (HasMassgap) is 26%.

For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 82 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 291 +/- 64 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] Ashton et al. ApJS 241, 27 (2019)
 [2] Chatterjee et al. ApJ 896, 1 (2020)
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