Stellar Collapse Diversity and the Diffuse Supernova Neutrino Background

Abstract

The diffuse cosmic supernova neutrino background (DSNB) is observational target of the gadoliniumloaded Super-Kamiokande (SK) detector and the forthcoming JUNO and Hyper-Kamiokande detectors. Current predictions are hampered by our still incomplete understanding of the supernova (SN) explosion mechanism and of the neutron star (NS) equation of state and maximum mass. In our comprehensive study we revisit this problem on grounds of the landscapes of successful and failed SN explosions obtained by Sukhbold et al. and Ertl et al. with parametrized one-dimensional neutrino engines for large sets of single-star and helium-star progenitors, with the latter serving as proxy of binary evolution effects. Besides considering engines of different strengths, leading to different fractions of failed SNe with black-hole (BH) formation, we also vary the NS mass limit, the spectral shape of the neutrino emission, and include contributions from poorly understood alternative NS-formation channels such as accretion-induced or merger-induced collapse events. Since the neutrino signals of our large model sets are approximate, we calibrate the associated degrees of freedom by using state-of-the-art simulations of proto-neutron star cooling. Our predictions are higher than other recent ones because of a large fraction of failed SNe with long delay to BH formation. Our best-guess model predicts a DSNB νe -flux of 28.8 +24.6 −10.9 cm −2 s −1 with 6.0 +5.1 −2.1 cm −2 s −1 in the favorable measurement interval of [10,30] MeV, and 1.3 +1.1 −0.4 cm −2 s −1 with νe energies > 17.3 MeV, which is roughly a factor of two below the current SK limit. The uncertainty range is dominated by the still insufficiently constrained cosmic rate of stellar core-collapse events.

Impact of binary interactions on the diffuse supernova neutrino background

“…Our results differ from those of Ref. [54] who conclude that binary interactions yield a reduction of the DSNB.…”

“…Recently, Ref. [54] made a first assessment of the impacts of binary interactions on the DSNB. The authors simulated the core collapse of progenitors stripped of its envelope due to mass loss [59] as a proxy for closebinary interactions.…”

Neutrino nonradiative decay and the diffuse supernova neutrino background

“…[12,21], we consider three scenarios: 𝑓 BH = 0.09, 0.21, 0.41 [9]. The last two cases are consistent with detailed supernova simulations [22]. Our fiducial model assumes 𝑓 BH = 0.21 and the core-collapse rate of Ref.…”

Prospects for the detection of the Diffuse Supernova Neutrino Background with the experiments SK-Gd and JUNO

“…This result is already cutting into the parameter range predicted by current DSNB models (e.g. [11]).…”

“…This makes the Diffuse Supernova Neutrino Background (DSNB), i.e. the faint but constant flux of neutrinos emitted by core-collapse SNe on cosmological distances, an attractive research objective [2][3][4][5][6][7][8][9][10][11]. A first measurement of the DSNB has the potential to provide valuable information on the redshift-dependent SN rate as well as on the average and variability of the SN neutrino spectrum.…”