Neutrino Emissions in All Flavors up to the Pre-bounce of Massive Stars and the Possibility of Their Detections

Abstract

This paper is a sequel to our 2015 paper, Kato et al., which calculated the luminosities and spectra of electron-type anti-neutrinos ( e n ) from the progenitors of core-collapse supernovae. Expecting that the capability to detect electron-type neutrinos ( e n ) will increase dramatically with the emergence of liquid-argon detectors such as DUNE, we broaden the scope in this study to include all flavors of neutrinos emitted from the pre-bounce phase. We pick up three progenitor models of electron capture supernovae (ECSNe) and iron-core collapse supernovae (FeCCSNe). We find that the number luminosities reach ∼10 57 s -1 and ∼10 53 s -1 at maximum for e n and e n , respectively. We also estimate the numbers of detection events at terrestrial neutrino detectors including DUNE, taking flavor oscillations into account and assuming the distance to the progenitors to be 200 pc. It is demonstrated that e n from the ECSN progenitor will be undetected at almost all detectors, whereas we will be able to observe 15,900 e n at DUNE for the inverted mass hierarchy. From the FeCCSN progenitors, the number of e n events will be largest for JUNO, 200-900 e n , depending on the mass hierarchy, whereas the number of e n events at DUNE is 2100  for the inverted mass hierarchy. These results imply that the detection of e n is useful to distinguish progenitors of FeCCSNe from those of ECSNe, while e n will provide us with detailed information on the collapse phase regardless of the type and mass of the progenitor.

Towards a complete reconstruction of supernova neutrino spectra in future large liquid-scintillator detectors

“…In this work, the pre-SN neutrino models from Guo et al [28] and Kato et al [16] will be adopted. The first set of Guo models contains the simulated neutrino data for four different progenitor star masses {12, 15, 20, 25} M (in units of the solar mass M ), in which only the pair process e + + e − → ν + ν has been considered for the advanced stellar evolution.…”

“…In addition, the liquid-argon time-projection chamber (LAr-TPC) detector of DUNE [27] is particularly sensitive to electron neutrinos due to the charged-current interaction ν e + 40 Ar → e − + 40 K * . The relatively high energy threshold of this reaction restricts the experimental sensitivity to pre-SN neutrinos, since only the high-energy ν e 's generated in the nuclear weak interactions in the last few minutes before collapse can be detected [16].…”

“…Only in the late stages of the stellar evolution, when the matter density and temperature are high enough, can neutrinos of MeV energies be generated in the stellar core and inner burning shells, which are called pre-SN neutrinos of particular interest for realistic detection. The contributions from nuclear weak interactions, including e ± capture on and β ± decays of heavy nuclei, to the pre-SN neutrino production become dominant in the last one hour or so prior to the core collapse [15,16]. Therefore, the detection of pre-SN neutrinos can be implemented to diagnose the late-time evolution of massive stars and serves as the early-warning signal for the subsequent core-collapse SN explosions.So far pre-SN neutrinos have not yet been detected.…”

“…For the next nearby galactic SN, the detectability of pre-SN neutrinos in current and future neutrino detectors with different target materials has been investigated in several previous works, e.g., Refs. [6,[15][16][17].Compared to the neutrino bursts from SN explosions, the typical energies of pre-SN neutrinos are much lower (i.e., a few MeV) and their fluxes are also much smaller, making their detection rather challenging. Three types of neutrino detectors have already been and will soon be available for this purpose.…”

“…For the next nearby galactic SN, the detectability of pre-SN neutrinos in current and future neutrino detectors with different target materials has been investigated in several previous works, e.g., Refs. [6,[15][16][17].…”