LIGO/Virgo/KAGRA S230520ae

IceCube Collaboration (http://icecube.wisc.edu/) reports:

Searches for track-like muon neutrino events detected by IceCube consistent with the sky localization of gravitational-wave candidate S230520ae  in a time range of 1000 seconds centered on the alert event time (2023-05-20 22:40:22.000 UTC to 2023-05-20 22:57:02.000 UTC) have been performed [1,2]. 

During this time period IceCube was collecting good quality data. No significant track-like events are found in spatial coincidence of S230520ae calculated from the map circulated in the 2-Preliminary notice.

IceCube's sensitivity assuming an E^-2 spectrum (E^2 dN/dE) to neutrino point sources within the locations spanned by the 90% spatial containment of S230520ae ranges from 0.028 to 1.133 GeV cm^-2 in a 1000 second time window.

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu.


[1] M. G. Aartsen et al 2020 ApJL 898 L10
[2] Abbasi et al. Astrophys.J. 944 (2023) 1, 80

The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report:

We identified the compact binary merger candidate S230520ae during real-time processing of data from LIGO Hanford Observatory (H1) and LIGO Livingston Observatory (L1) at 2023-05-20 22:48:42.560 UTC (GPS time: 1368658140.560). The candidate was found by the MBTA [1], CWB [2], PyCBC Live [3], SPIIR [4], and GstLAL [5] analysis pipelines.

S230520ae is an event of interest because its false alarm rate, as estimated by the online analysis, is 3.1e-09 Hz, or about one in 10 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S230520ae

The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), or NSBH (<1%).

Assuming the candidate is astrophysical in origin, the probability that the lighter compact object has a mass < 3 solar masses (HasNS) is <1%. [6] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [6]

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 [7], distributed via GCN notice about 29 seconds after the candidate event time.
 * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [7], 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 1716 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1974 +/- 583 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] Adams et al. CQG 33, 175012 (2016)
 [2] Klimenko et al. PRD 93, 042004 (2016)
 [3] Dal Canton et al. ApJ 923, 254 (2021)
 [4] Qi Chu, PhD Thesis, The University of Western Australia (2017)
 [5] Messick et al. PRD 95, 042001 (2017)
 [6] Chatterjee et al. The Astrophysical Journal 896, 1 (2020)
 [7] Singer & Price PRD 93, 024013 (2016)

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 S230520ae (GCN Circular 33838
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 ). 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/S230520ae

For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 1702 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2014 +/- 663 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)