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J.F. Beacom
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The next core-collapse supernova in our Galaxy will be a spectacular event, with some $10^4$ neutrino detections in total expected among several detectors. This data will allow unprecedented tests of neutrino properties and new opportunities in astrophysics. In this paper, I focus on two main topics: (1) Measurement of the $ u_mu$ and $ u_tau$ masses by time-of-flight, with an emphasis on introducing as little supernova model dependence as possible, and (2) Methods for locating a supernova by its neutrinos in advance of the light, which may allow improved astronomical observations. In the latter, I also discuss the recent result that the positrons from $bar{ u}_e + p to e^+ + n$ are not isotropically emitted, as commonly thought.
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Core-collapse supernovae emit of order $10^{58}$ neutrinos and antineutrinos of all flavors over several seconds, with average energies of 10--25 MeV. In the Sudbury Neutrino Observatory (SNO), a future Galactic supernova at a distance of 10 kpc would cause several hundred events. The $ u_mu$ and $ u_tau$ neutrinos and antineutrinos are of particular interest, as a test of the supernova mechanism. In addition, it is possible to measure or limit their masses by their delay (determined from neutral-current events) relative to the $bar{ u}_e$ neutrinos (determined from charged-current events). Numerical results are presented for such a future supernova as seen in SNO. Under reasonable assumptions, and in the presence of the expected counting statistics, a $ u_mu$ or $ u_tau$ mass down to about 30 eV can be simply and robustly determined. This seems to be the best technique for direct measurement of these masses.
We model the distance, extinction, and magnitude probability distributions of a successful Galactic core-collapse supernova (ccSN), its shock breakout radiation, and its massive star progenitor. We find, at very high probability (~100%), that the next Galactic SN will easily be detectable in the near-IR and that near-IR photometry of the progenitor star very likely (~92%) already exists in the 2MASS survey. Most ccSNe (~98%) will be easily observed in the optical, but a significant fraction (~43%) will lack observations of the progenitor due to a combination of survey sensitivity and confusion. If neutrino detection experiments can quickly disseminate a likely position (~3 deg), we show that a modestly priced IR camera system can probably detect the shock breakout radiation pulse even in daytime (~64% for the cheapest design). Neutrino experiments should seriously consider adding such systems, both for their scientific return and as an added and internal layer of protection against false triggers. We find that shock breakouts from failed ccSNe of red supergiants may be more observable than those of successful SNe. We review the process by which neutrinos from a Galactic ccSN would be detected and announced. We provide new information on the EGADS system and its potential for providing instant neutrino alerts. We also discuss the distance, extinction, and magnitude probability distributions for the next Galactic Type Ia SN. Based on our modeled observability, we find a Galactic ccSN rate of 3.2 (+7.3/-2.6) per century and a Galactic Type Ia SN rate of 1.4 (+1.4/-0.8) per century for a total Galactic SN rate of 4.6 (+7.4/-2.7) per century is needed to account for the SNe observed over the last millennium.
In core-collapse supernovae, neutrinos and antineutrinos are initially subject to significant self-interactions induced by weak neutral currents, which may induce strong-coupling effects on the flavor evolution (collective transitions). The interpretation of the effects is simplified when self-induced collective transitions are decoupled from ordinary matter oscillations, as for the matter density profile that we discuss. In this case, approximate analytical tools can be used (pendulum analogy, swap of energy spectra). For inverted neutrino mass hierarchy, the sequence of effects involves: synchronization, bipolar oscillations, and spectral split. Our simulations shows that the main features of these regimes are not altered when passing from simplified (angle-averaged) treatments to full, multi-angle numerical experiments.
Neutrino oscillations in the Earth matter may introduce peculiar modulations in the supernova (SN) neutrino spectra. The detection of this effect has been proposed as diagnostic tool for the neutrino mass hierarchy at large 1-3 leptonic mixing angle theta13. We perform an updated study on the observability of this effect at large next-generation underground detectors (i.e., 0.4 Mton water Cherenkov, 50 kton scintillation and 100 kton liquid Argon detectors) based on neutrino fluxes from state-of-the-art SN simulations and accounting for statistical fluctuations via Montecarlo simulations. Since the average energies predicted by recent simulations are lower than previously expected and a tendency towards the equalization of the neutrino fluxes appears during the SN cooling phase, the detection of the Earth matter effect will be more challenging than expected from previous studies. We find that none of the proposed detectors shall be able to detect the Earth modulation for the neutrino signal of a typical galactic SN at 10 kpc. It should be observable in a 100 kton liquid Argon detector for a SN at few kpc and all three detectors would clearly see the Earth signature for very close-by stars only (d ~ 0.2 kpc). Finally, we show that adopting IceCube as co-detector together with a Mton water Cherenkov detector is not a viable option either.
The neutrino burst from a galactic supernova can help determine the neutrino mass hierarchy and $theta_{13}$, and provide crucial information about supernova astrophysics. Here we review our current understanding of the neutrino burst, flavor
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