TITLE: GCN CIRCULAR NUMBER: 26249 SUBJECT: LIGO/Virgo S191110af: Upper limits from KM3NeT MeV neutrino search. DATE: 19/11/14 20:04:49 GMT FROM: Damien Dornic at CPPM,France M. Colomer (APC, Universite de Paris), M. Lincetto (Aix Marseille Univ, CNRS/IN2P3, CPPM), A. Coleiro (APC, Universite de Paris), D. Dornic (Aix Marseille Univ, CNRS/IN2P3, CPPM), V. Kulikovskiy (INFN - Sezione di Genova), report on behalf of the KM3NeT Collaboration. Using online data from the KM3NeT detector, we have performed a follow-up analysis of the recently reported gravitational-wave (GW) burst candidate S191110af (GCN #26222) to investigate the possibility that this burst was emitted by a core-collapse supernova (CCSN) event. KM3NeT can detect ~10 MeV neutrinos from a Galactic CCSN through a collective rise of the photomultiplier (PMT) detection rates on top of the noise due to the Cherenkov light produced by the interaction of electron antineutrinos through inverse beta decay. This is expected mostly during the CCSN accretion phase (lasting a few hundred ms) where most of the electron antineutrinos are supposed to be emitted [1]. No CCSN trigger in the KM3NeT/ORCA online infrastructure was detected during a 400 ms time-window, starting at the time of the GW trigger, while 0.8 events are expected on average from the background at trigger time. Using Feldman and Cousins approach, a preliminary 90% confidence level upper limit on the number of signal events is estimated. Assuming two progenitor models from the Garching group [2] with masses of 27 Msun and 11.2 Msun, we derive an upper limit on the distance of the potential source of 11.4 kpc and 5.7 kpc respectively. Moreover, assuming a quasi-thermal neutrino spectrum as in [2] with a spectral pinching parameter value of 3 and a mean neutrino energy of 15 MeV and assuming that 70% of the energy is released in the 400 ms, the total energy emitted into neutrinos from this GW burst candidate is determined to be E < 2.8e53 erg at 10 kpc. KM3NeT detectors are currently under construction in the Mediterranean Sea. The ORCA detector is nowadays composed of an array of 4 instrumented lines, each containing 18 digital optical modules hosting 31 directional PMTs. It is equivalent to a 3 kton CCSN neutrino detector. With the current configuration, ORCA detector can detect a CCSN at 5 sigma up to 3.5 and 7.5 kpc respectively for the low and high-mass progenitor considered in the CCSN neutrino flux models of the Garching group. [1] M. Colomer, M. Lincetto et al. (on behalf of the KM3NeT collaboration), PoS(ICRC2019)857. [2] I. Tamborra et al., Phys. Rev. D, 90 (2014).