{
"subject": "LIGO/Virgo S190808ae: One Coincident Neutrino Candidate from IceCube Search",
"bibcode": "2019GCN.25297....1I",
"createdOn": 1565308432000,
"circularId": 25297,
"submitter": "Raamis Hussain at IceCube ",
"email": "raamis.hussain@icecube.wisc.edu",
"body": "IceCube Collaboration (http://icecube.wisc.edu/) reports:\n\nSearches for track-like muon neutrino events detected by IceCube consistent\nwith the sky localization of gravitational-wave candidate S190808ae in a\ntime range of 1000 seconds [1] centered on the alert event time\n(2019-08-08 22:13:01.496 UTC to 2019-08-08 22:29:41.496 UTC) have been\nperformed.\nDuring this time period IceCube was collecting good quality data. Two\nhypothesis tests were conducted. The first search is a maximum likelihood\nanalysis which searches for a generic point-like neutrino source coincident\nwith the given GW skymap [2]. The second uses a Bayesian approach to\nquantify the joint GW + neutrino event significance, which assumes a binary\nmerger scenario and accounts for known astrophysical priors in the\nsignificance estimate, such as GW source distance [3].\n\nOne track-like event is found in spatial and temporal coincidence with the\ngravitational-wave candidate S190808ae calculated from the map circulated in\nthe 2-Initial notice. This represents an overall p-value of 0.0448 (1.70\nsigma) from the generic transient search and an overall p-value of 0.068\n(1.49 sigma) for the Bayesian search. These p-values measure the\nconsistency of the observed track-like events with the known atmospheric\nbackgrounds.\n\nThe reported p-values can differ due to the estimated distance of the GW\ncandidate. The distance is used as a prior in the Bayesian binary merger\nsearch, while it is not taken into account in the generic transient\npoint-like source search.\n\nProperties of the coincident event are shown below.\n\ndt | ra (deg) | dec (deg) | Angular Uncertainty(deg) | p-value(generic\ntransient) | p-value(bayesian)\n-----+--------+---------+------------------------+------------------+--------------------------\n -37 | 216.29 |-15.35 | 0.43 |0.045\n |0.070\n\nwhere:\ndt = Time offset (sec) of track event with respect to GW trigger. Angular\nuncertainty = Angular uncertainty of track event: the radius of a circle\nrepresenting 90% CL containment by area.\np-value = the p-value for this specific track event from each search.\nRA & Dec = Right ascension and declination in degrees quoted in J2000 epoch\n\nThe IceCube Neutrino Observatory is a cubic-kilometer neutrino detector\noperating at the geographic South Pole, Antarctica. The IceCube realtime\nalert point of contact can be reached at roc@icecube.wisc.edu\n\n[1] Baret et al., Astroparticle Physics 35, 1 (2011)\n[2] Braun et al., Astroparticle Physics 29, 299 (2008)\n[3] Bartos et al. arXiv:1810.11467 (2018) and Countryman et\nal.arXiv:1901.05486 (2019)```"
}