SUPERNOVA RELIC NEUTRINOS AND THE SUPERNOVA RATE PROBLEM: ANALYSIS OF UNCERTAINTIES AND DETECTABILITY OF ONeMg AND FAILED SUPERNOVAE

Abstract

Direct measurements of the core-collapse supernova rate (R SN ) in the redshift range 0 ≤ z ≤ 1 appear to be about a factor of two smaller than the rate inferred from the measured cosmic massivestar formation rate (SFR). This discrepancy would imply that about one half of the massive stars that have been born in the local observed comoving volume did not explode as luminous supernovae. In this work we explore the possibility that one could clarify the source of this "supernova rate problem" by detecting the energy spectrum of supernova relic neutrinos with a next generation 10 6 ton wateř Cerenkov detector like Hyper-Kamiokande. First, we re-examine the supernova rate problem. We make a conservative alternative compilation of the measured SFR data over the redshift range 0 ≤ z ≤ 7. We show that, by only including published SFR data for which the dust obscuration has been directly determined, the ratio of the observed massive SFR to the observed supernova rate R SN has large uncertainties ∼ 1.8 +1.6 −0.6 , and is statistically consistent with no supernova rate problem. If we further consider that a significant fraction of massive stars will end their liives as faint ONeMg SNe or as failed SNe leading to a black hole remnant, then the ratio reduces to ∼ 1.1 +1.0 −0.4 and the rate problem is essentially solved. We next examine the prospects for detecting this solution to the supernova rate problem. We first study the sources of uncertainty involved in the theoretical estimates of the neutrino detection rate and analyze whether the spectrum of relic neutrinos can be used to independently identify the existence of a supernova rate problem and its source. We consider an ensemble of published and unpublished core collapse supernova simulation models to estimate the uncertainties in the anticipated neutrino luminosities and temperatures. We illustrate how the spectrum of detector events might be used to establish the average neutrino temperature and constrain SN models. We also consider supernova ν-process nucleosynthesis to deduce constraints on the temperature of the various neutrino flavors. We study the effects of neutrino oscillations on the detected neutrino energy spectrum and also show that one might distinguish the equation of state (EoS) as well as the cause of the possible missing luminous supernovae from the detection of supernova relic neutrinos. We also analyze a possible enhanced contribution from failed supernovae leading to a black hole remnant as a solution to the supernova rate problem. We conclude that indeed it might be possible (though difficult) to measure the neutrino temperature, neutrino oscillations, the EOS, and confirm this source of missing luminous supernovae by the detection of the spectrum of relic neutrinos.

RETRACTED ARTICLE: r-process nucleosynthesis in the MHD+neutrino-heated collapsar jet

“…Observationally, collapsars are expected (Mathews et al 2014) to only result from a very small fraction (0.04%) of stars in the range of 25 M < m < 125 M . On the other hand, the core collapse supernova rate involves progenitor stars in the range of 10 M < m < 25 M .…”

Study of Red Supergiant and Supernova Rate Problems via Relic Supernova Neutrino Spectrum

“…The result is shown in Figure 1, which includes three lines due to the uncertainties of IMF (see equation (3)). Dotted lines indicate the upper and lower limits due to the uncertainties of SFR [4]. Adopted value M f S N min = 16.5 − 18 M ⊙ clearly solves the SNR problem, although it is important to notice that R T hr S N depends strongly on SFR.…”

“…whereρ 0 = 0.0104 M ⊙ Mpc −3 yr −1 , α = 4.22, β = −0.20, γ = −11.30, B = 2.70 × 10 6 , C = 6.37 [4,12]. The total flux, dN tot ν /dE ν is the sum of neutrino fluxes from all types of SNe, and we estimate the detector event rate by…”

“…The cosmic relic supernova neutrinos (RSNs), i.e., the diffuse supernova neutrino background from all types of core-collapse supernovae (SNe), offers useful tool to investigate not only the micro-physics of SNe but also star formation history through the cosmic evolution [1][2][3][4]. All details about the types of SNe and their explosion mechanisms are, therefore, imprinted in RSN spectrum.…”

Theory and phenomenology of supernova neutrinos

“…(2) [2,61,62]. In particular, neutrino fluxes from the latest supernova numerical simulations have been used, to include the effect of the cooling of the neutrino flux over several seconds.…”