Can one observe Earth matter effects with supernova neutrinos?

Abstract

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 θ13. 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.

Combining collective, MSW, and turbulence effects in supernova neutrino flavor evolution

“…A turbulent density profile would also imply neutrinos of the same energy arriving at the same time in a detector but emitted from different locations at the proto-neutron star will not have experienced the same flavor density profile history [72,73]. Finally, once the star is left behind and the neutrinos have reached Earth recent studies indicate that fortunately/unfortunately (depending upon one's point of view) Earth matter effects on the neutrino signal may be minimal [74].…”

Consequences of largeθ13for the turbulence signatures in supernova neutrinos

“…The rich phenomenology of neutrino collective effects [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] (for a review see [16,17]) have received the most attention but there has been an equally radical overhaul of the Mikheyev, Smirnov & Wolfenstein (MSW) [18,19] effect as applied to supernovae ever since it was realized by Schirato & Fuller [20] that the shockwave racing through the stellar mantle could leave an imprint upon the neutrinos emitted from the cooling proto-neutron star [20][21][22][23][24][25][26]. Recent studies indicate Earth matter effects may be minimal [27]. From this ever-growing body of literature one now expects that the neutrino signal from the next supernova in our Galaxy will be pregnant with information.…”

Theory and phenomenology of supernova neutrinos

“…In particular, the disappearance of the peak in ν e (neutronization) due to complete ν e →ν x conversion would be a clear signature of the normal ordering [24,25]. Another such signature could be an oscillatory distortion of thē ν e spectrum at Earth, due to oscillations inside the Earth, which have non-zero amplitude only if the ordering is normal (see e.g., [17,26]). Instead, a similar oscillatory pattern is expected to appear in ν e if the mass ordering is inverted.…”

“…Instead, a similar oscillatory pattern is expected to appear in ν e if the mass ordering is inverted. However, this Earth effect is of the order of ∼ 5 − 10% [26], and therefore requires high statistics and very good energy resolution to be seen ( fig. 4).…”