E9 : Low energy astrophysics with KM3NET

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    Although multi-wavelength observations of core-collapse supernovae (CCSN) are now routinely performed, specific features of the gravitational collapse can only be diagnosed by neutrinos.


    The objective of this exploratory project is to bring together experts in CCSN physics and members of the KM3NeT collaboration to assess the capability of the KM3NeT neutrino telescopes (optimized for GeV-PeV neutrinos) to detect MeV neutrino signal from the next close-by CCSN.


    Using state-of-the-art numerical simulations and theoretical developments, we explore the potential of the novel KM3NeT optical module design to efficiently suppress the background, and thus to detect features of the neutrino light curve related to hydrodynamical instabilities, neutron star equation of state, and neutrino properties.




    WP leader Alexis Coleiro APC Post-doc, IFIC / APC, associate researcher
    WP co-leader Thierry Foglizzo AIM IR, CEA
    WP member Antoine Kouchner APC PR, Univ. Paris Diderot
    WP member Bruno Pagani AIM PhD, ED127
    WP member Julien Aublin APC MCF, UPMC, associate researcher
    WP member Micaela Oertel LUTh CR, CNRS
    WP member Cristina Volpe APC DR, CNRS
    WP member Bruny Baret APC CR, CNRS
    WP member Marta Colomer-Molla APC PhD student, Univ. Paris Diderot / IFIC Valencia

  • Although KM3NeT detectors are mainly designed for high-energy neutrino detection, the MeV neutrino signal from a supernova might be identified as a simultaneous increase of the counting rate of the optical modules in the detector.

    The main interaction modes of these MeV neutrinos in water are the interactions with (i) free protons (Inverse Beta Decay, IBD), (ii) electrons (Elastic Scattering, ES) and (iii) Oxygen nuclei. The outgoing particles (electron or positron) produced through these interactions radiate Cherenkov light that can be detected by photomultiplier (PMT) arrays.
    Optical background, due to both 40K decay in sea water and bioluminescence, can be significantly reduced by using nanosecond coincidences between nearby PMTs. This technique has been tested with the ANTARES telescope, consisting of optical modules (OMs) with three 10-inch PMTs and is currently being optimized for the nextgeneration of European neutrino telescopes KM3NeT, whose directional OMs containing 31 3-inch PMTs, provide with promising expectations. The Exploratory project LEAK aims at investigating these capabilities. In particular, the Labex fundings obtained in 2017 have facilitated the organization of face-to-face meetings to finalize the implementation of the full simulations of KM3NeT sensitivity to MeV neutrinos described hereafter.

    The development of this simulation was identified as a critical milestone of the project and has been started by Marta Colomer-Molla during her M2/NPAC internship. She is now continuing the projet as a PhD student in the KM3NeT collaboration (cotutelle between the University Paris Diderot / APC and the University of Valencia / IFIC).

    Based on the full Monte-Carlo simulation implemented in 2017, we are now in a good position to start an accurate study of the capabilities of KM3NeT to detect a CCSN signal, and derive observational signatures imprinted in the neutrino lightcurve and/or neutrino spectrum that could be detected with those neutrino telescopes. In particular, we plan to focus on the neutrino flux features related to the hydrodynamic instabilities (such as SASI activity), the neutron star equation of state (EOS) and the neutrino mass hierarchy (MH). At the end of the year 2018, we will have defined the most relevant effects that might be observed with KM3NeT in order to constrain the core-collapse physics (hydrodynamic instabilities occuring during the accretion phase), the neutron star properties (equation of state of dense matter) and neutrino properties (neutrino mass hierarchy).


    Three main milestones are expected for 2018 and 2019:
    1) Organization of a workshop dedicated to CCSN neutrino detection;
    2) End of the implementation of the Monte-Carlo simulation of the detector and test of KM3NeT sensitivity to the CCSN neutrino signature of the dynamic instabilities, neutron star equation of state and neutrino mass hierarchy (in close collaboration with CCSN experts involved in the project);
    3) Integration of the CCSN real-time detection/analysis tools in the KM3NeT data acquisition systems.



    • M. Colomer-Molla et al. on behalf of the KM3NeT collaboration, ICRC 2017 proceedings.