Neutrinos from type Ia supernovae: The gravitationally confined detonation scenario

Despite their use as cosmological distance indicators and their importance in the chemical evolution of galaxies, the unequivocal identification of the progenitor systems and explosion mechanism of normal type Ia supernovae (SNe Ia) remains elusive. The leading hypothesis is that such a supernova is a thermonuclear explosion of a carbon-oxygen white dwarf, but the exact explosion mechanism is still a matter of debate. Observation of a galactic SN Ia would be of immense value in answering the many open questions related to these events. One potentially useful source of information about the explosion mechanism and progenitor is the neutrino signal because the neutrinos from the different mechanisms possess distinct spectra as a function of time and energy. In this paper, we compute the expected neutrino signal from a gravitationally confined detonation (GCD) explosion scenario for a SN Ia and show how the flux at Earth contains features in time and energy unique to this scenario. We then calculate the expected event rates in the Super-K, Hyper-K, JUNO, DUNE, and IceCube detectors and find both Hyper-K and IceCube will see a few events for a GCD supernova at 1 kpc or closer, while Super-K, JUNO, and DUNE will see events if the supernova is closer than $\sim 0.3\mathrm{kpc}$. The distance and detector criteria needed to resolve the time and spectral features arising from the explosion mechanism, neutrino production, and neutrino oscillation processes are also discussed. The neutrino signal from the GCD is then compared with the signal from a deflagration-to-detonation transition (DDT) explosion model computed previously. We find the overall event rate is the most discriminating feature between the two scenarios followed by the event rate time structure. Using the event rate in the Hyper-K detector alone, the DDT can be distinguished from the GCD at $2\sigma$ if the distance to the supernova is less than 2.3 kpc for a normal mass ordering and 3.6 kpc for an inverted ordering.

Figure 1

Density contour plots including deflagration (white) and detonation (green) surfaces.

Figure 2

GCD total neutrino luminosity for electron neutrino and electron anti neutrino weak processes, and for pair production (all flavors). The dots represent the actual calculation and the lines are a linear interpolation. The middle gap in neutrino emission results from a lack of any NSE stellar zones for these times.

Figure 3

GCD neutrino luminosity spectra. Each curve is the sum of all considered weak and thermal processes. The top plots represent the initial ($0.1\mathrm{s}<t<1.3\mathrm{s}$) neutrino burst corresponding to the initial deflagration and the bottom plots represent the secondary ($2.5\mathrm{s}<t<3.3\mathrm{s}$) neutrino burst corresponding to the detonation.

Figure 4

Density profiles for various time slices of the GCD simulation. The left panel represents the trajectory that is aligned with the initial deflagration plume (positive $z$ axis). The right panel represents the trajectory opposite to the left panel’s trajectory, i.e. the trajectory aligned with where detonation is initiated (negative $z$ axis).

Figure 5

The neutrino matter basis transition probabilities $P_{ij}^{(\mathrm{m})}(E_{\nu })$ as a function of energy. The top row, from left to right, shows $P_{11}^{(\mathrm{m})}$, $P_{12}^{(\mathrm{m})}$ and $P_{13}^{(\mathrm{m})}$. The middle row from left to right shows $P_{21}^{(\mathrm{m})}$, $P_{22}^{(\mathrm{m})}$ and $P_{23}^{(\mathrm{m})}$ and the bottom row from left to right shows $P_{31}^{(\mathrm{m})}$, $P_{32}^{(\mathrm{m})}$ and $P_{33}^{(\mathrm{m})}$. The mass ordering is normal and the snapshot time is $t=0.4\mathrm{s}$. The polar and azimuth angles of each trajectory are given in the legend.

Figure 6

The antineutrino matter basis transition probabilities for normal mass ordering at $t=0.4\mathrm{s}$. The structure and layout is the same as that of Fig. 5.

Figure 7

The neutrino matter basis transition probabilities for inverted mass ordering at $t=0.4\mathrm{s}$. The structure and layout is the same as that of Fig. 5.

Figure 8

The antineutrino matter basis transition probabilities for inverted mass ordering at $t=0.4\mathrm{s}$. The structure and layout is the same as that of Fig. 5.

Figure 9

The neutrino matter basis transition probabilities for normal mass ordering at $t=2.9\mathrm{s}$. The structure and layout is the same as that of Fig. 5.

Figure 10

The antineutrino matter basis transition probabilities for normal mass ordering at $t=2.9\mathrm{s}$. The structure and layout is the same as that of Fig. 5.

Figure 11

The neutrino matter basis transition probabilities for inverted mass ordering at $t=2.9\mathrm{s}$. The structure and layout is the same as that of Fig. 5.

Figure 12

The antineutrino matter basis transition probabilities for inverted mass ordering at $t=2.9\mathrm{s}$. The structure and layout is the same as that of Fig. 5.

Figure 13

The electron neutrino survival probability $P_{ee}$ at Earth as a function of neutrino energy for each of the ten lines-of-sight through the simulation at the ten snapshot times. The mass ordering is normal.

Figure 14

The electron antineutrino survival probability ${\overline{P}}_{ee}$ at Earth as a function of neutrino energy for each of the ten lines-of-sight through the simulation at the ten snapshot times. The mass ordering is normal.

Figure 15

The same as figure (13) but for an inverted mass hierarchy.

Figure 16

The same as figure (14) but for an inverted mass hierarchy.

Figure 17

The neutrino and antineutrino flux for each flavor from the GCD simulation at 10 kpc after oscillations for a NMO. Line thickness represents line-of-sight variation. In the top figure are the five snapshot times during the deflagration phase $t=0.1\mathrm{s}$ to $t=1.3\mathrm{s}$, the bottom figure shows the flux during the detonation phase $t=2.5\mathrm{s}$ to $t=3.3\mathrm{s}$. The color of each line indicates the snapshot time shown in the legend to the right of the figures.

Figure 18

The same as figure (17) but for an IMO.

Figure 19

The neutrino and antineutrino flux for each flavor from the GCD simulation at 10 kpc in the absence of flavor oscillations. In the top figure are the five snapshot times during the deflagration phase $t=0.1\mathrm{s}$ to $t=1.3\mathrm{s}$, the bottom figure shows the flux during the detonation phase $t=2.5\mathrm{s}$ to $t=3.3\mathrm{s}$. The color of each line indicates the snapshot time shown in the legend to the right of the figures.

Figure 20

A plot of the interaction event rate in Hyper-K for a particular line of sight for a GCD SN Ia at 10 kpc. The left column is for NMO and the right column is for IMO.

Figure 21

The energy-integrated interaction event rate in Hyper-K, Super-K, DUNE, and JUNO for a GCD SN Ia at 10 kpc. The curve thickness indicates line-of-sight variation and the horizontal lines show how the rate ($y$ axis) would shift for nearer SN. The left column is for NMO and the right column is for IMO.

Figure 22

The detector event spectrum in Hyper-K, Super-K, JUNO, and DUNE for a GCD SN Ia at 10 kpc. The curve thickness and shading indicates line-of-sight variation and the horizontal lines show how the rate ($y$ axis) would shift for nearer SN. The top row are for deflagration burst ($0.1\mathrm{s}<t<1.3\mathrm{s}$), the middle row for the detonation burst ($2.5\mathrm{s}<t<3.3\mathrm{s}$), and the bottom row are for the whole neutrino signal ($0.1\mathrm{s}<t<3.3\mathrm{s}$). The left column is for NMO and the right column is for IMO.

Figure 23

The detector event spectrum in Hyper-K and DUNE for a GCD SN Ia at 10 kpc integrated over the detonation burst i.e for $2.5\mathrm{s}<t<3.3\mathrm{s}$. The left column is for NMO and the right column is for IMO. The thickness of the red and purple curves indicate the line-of-sight variation and the horizontal lines show how the rate ($y$ axis) would shift for nearer SN. Detector energy smearing has been applied to the red and purple curves. The background gray curves represent the un-smeared event counts for comparison: the dark gray is for DUNE, the lighter gray for Hyper-K.

Figure 24

A comparison of the neutrino luminosities for the DDT and GCD SN Ia simulations. The layout and structure is similar to that of Fig. 2.

Figure 25

A comparison of the differential neutrino flux on Earth for the DDT and GCD SN Ia simulations. The fluxes include the effects of oscillations for a NMO and $d=10\mathrm{kpc}$. The three columns are for the three flavors of neutrinos. The top row shows the spectra at two snapshots during the deflagration burst of each simulation ($t_{\mathrm{GCD}}=0.4\mathrm{s}$ and $t_{\mathrm{DDT}}=0.55\mathrm{s}$) and the bottom row shows the spectra at two snapshots during the detonation burst of each simulation ($t_{\mathrm{GCD}}=2.9\mathrm{s}$ and $t_{\mathrm{DDT}}=1.3\mathrm{s}$). The simulation and the snapshot times are shown in the legend to the right. For each spectrum shown, the thickness of the curve indicates the range due to the line-of-sight variation through each calculation.

Figure 26

The time evolution of the event rate in Hyper-K and DUNE for DDT and GCD simulations of a SN Ia at 10 kpc. The shadowed regions represent the effects of neutrino oscillation such that the top of each shadowed region represents the associated unoscillated event rate. The lines represent the mean event rate across all neutrino trajectories considered. Similarly, the error bars represent the $3\sigma$ deviation due to line-of-sight variations in the event rates. The left (right) plot is for normal (inverted) mass ordering. The horizontal lines show how the event rate would change if the supernova occurred at a closer distance.

Figure 27

The total number of events predicted to be measured in the Hyper-K detector as a function of the distance to the SN for both the DDT (red) and the GCD (blue) models. The left panel is for NMO and the right panel is the IMO. The shaded regions represent the event count range given a $1\sigma$ to $3\sigma$ Poisson error (also including a small error associated with line-of-sight uncertainty). The smallest, darkest shaded area represents the $1\sigma$ event range and the largest, lightest shaded area represents the $3\sigma$ event range for each model. The black dots show the distance at which the DDT total event count can be distinguished from the GCD total event count for a given $\sigma$ confidence. For NMO these distances are, from left to right, $(d_{3\sigma },d_{2\sigma },d_{1\sigma })=(1.51,2.26,4.52)\mathrm{kpc}$. For IMO, these distances are, from left to right, $(d_{3\sigma },d_{2\sigma },d_{1\sigma })=(2.38,3.57,7.13)\mathrm{kpc}$.

Figure 28

The total number of events predicted to be measured in the Hyper-K detector as a function of the distance to the SN for both NMO (green) and IMO (orange). The left panel is for the DDT model and the right panel is the GCD model. The shaded regions represent the event count range given a $1\sigma$ to $3\sigma$ Poisson error (also including a small error associated with line-of-sight uncertainty). The smallest, darkest shaded area represents the $1\sigma$ event range and the largest, lightest shaded area represents the $3\sigma$ event range for each model. The black dots show the distance at which NMO can be distinguished from IMO for a given $\sigma$ confidence. For DDT these distances are, from left to right, $(d_{3\sigma },d_{2\sigma },d_{1\sigma })=(1.05,1.58,3.17)\mathrm{kpc}$. For GCD these distances are, from left to right, $(d_{3\sigma },d_{2\sigma },d_{1\sigma })=(0.18,0.27,0.55)\mathrm{kpc}$.

Figure 29

The time evolution of the event rate spectra in Hyper-K and DUNE for DDT and GCD simulations of a SN Ia at 10 kpc. The lines thickness represents the effect of line-of-sight variation. The left (right) plots are for normal (inverted) mass ordering. The horizontal lines show how the event rate would change if the supernova occurred at a closer distance. The top row represents the rate averaged over the deflagration burst and the bottom row represents the rate averaged over the detonation burst.