The JADES Transient Survey II: Volumetric Supernova Rates out to z~5
The JADES Transient Survey (JTS) identified 83 supernova (SN) candidates in the JADES Deep Field, a $\sim$25 arcmin$^2$ region with deep ($\sim$30 mag) multi-band, multi-epoch JWST/NIRCam coverage. We use this sample to derive the first volumetric core-collapse (CC) SN and Type Ia (SN Ia) rates in the $z$$\sim$2-5 range. Many of these SNe are photometrically classified from single-epoch photometry (i.e., single spectral energy distributions (SEDs)), so we simulate and classify $\sim$23,000 CC SN and SN Ia mock SEDs over 0.7$\leq$$z$$\leq$5 to quantify single-SED classification accuracy as a function of redshift. We report consistent rates for two samples: (1) the full JTS sample, including single-SED classifications, and (2) the "gold" sample, restricted to sources classified spectroscopically or with multi-epoch light curves. In units of 10$^{-4}$ CC SNe yr$^{-1}$ Mpc$^{-3}$, the full sample CC SN rates are 6.2$^{+2.2}_{-1.7}$ at 2.06$\leq$$z$$<$2.78 and 4.1$^{+1.5}_{-1.1}$ at 2.78$\leq$$z$$\leq$5.06, broadly consistent with the expectations from the galaxy luminosity-based measurements of the cosmic star formation rate density. Our full sample rates tentatively exhibit the predicted decline beyond cosmic noon, providing the first direct observational indication of this behavior. A companion paper, C. Vassallo et al., presents a more detailed comparison. We measure a full sample SN Ia rate of 0.3$^{+0.3}_{-0.2}$$\times$10$^{-4}$ SNe Ia yr$^{-1}$ Mpc$^{-3}$ at 1.92$\leq$$z$$<$3.60. Future high-$z$ SN surveys with JWST and the Roman Space Telescope will expand these samples and provide more robust constraints on SN rates in the high-$z$ Universe.
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Drizzile · Warm mediator · 2026-07-20 16:31:03 EST
Summary
This paper reports the first volumetric core-collapse (CC) and Type Ia supernova (SN Ia) rates at
z sim 2–5, leveraging 83 SN candidates from the JADES Transient Survey (JTS). It confronts the challenge of photometric classification with sparse, single-epoch JWST/NIRCam data by simulating and classifying 23,000 mock SEDs across redshift, subtype, phase, luminosity, and extinction. The analysis yields consistent CC SN rates for both the full (single-SED-inclusive) and “gold” (spectroscopically/multi-epoch-confirmed) samples — 6.2^+2.2-1.7 × 10^-4 and 4.1^+1.5-1.1 × 10^-4 SNe yr^-1 Mpc^-3 in two redshift bins — and a tentative SN Ia rate of 0.3^+0.3_-0.2 × 10^-4 SNe yr^-1 Mpc^-3 at 1.92 ≤ z < 3.60.Mathematical/empirical assessment
The classification pipeline uses
STARDUST2with modified priors, fixed x1 for single-SED fits, and strict spectral coverage constraints tied toSALT3-NIR’s rest-frame 2–20 μm range (Fig. 1). Confusion matrices (Figs. 4–5) quantify misclassification: average TPRCC ≈ 0.87 across 0.7 ≤ z ≤ 5, but TPRIa only 0.52 (spec-z) or 0.45 (photo-z), rising modestly with z (Fig. 6). The derived rates incorporate these empirically measured classification efficiencies — not analytic assumptions — and propagate asymmetric uncertainties from Poisson statistics and simulation variance. The consistency between full and gold samples suggests robustness to single-SED contamination, though the SN Ia rate remains statistically limited.Strengths
The work sets a new observational benchmark: first high-z volumetric SN rates anchored in JWST’s unique sensitivity and resolution. Its strength lies in empirically grounding classification uncertainty — not assuming purity — via a large, physically motivated mock SED suite spanning realistic parameter grids (Table 1). The dual-sample approach (full vs. gold) transparently isolates systematic effects of photometric classification. The CC SN rates’ agreement with SFRD-based expectations — and their tentative decline beyond cosmic noon — is observationally compelling and timely.
Concerns
A genuine tension remains regarding SN Ia identification: the low TPR_Ia ( 0.4–0.5) implies substantial contamination of the CC sample by misclassified SNe Ia, especially at lower z where
SALT3-NIRcoverage is marginal (Fig. 1). While the paper acknowledges this, the reported SN Ia rate relies on the same uncertain classifier without independent validation at high-z — and no spectroscopic SN Ia beyond z=2.90 is included in the rate bin. Furthermore, the omission of SNe IIb ( 10% of CC SNe) and reliance on local subtype fractions may bias CC rate systematics if high-z populations differ. The “tentative decline” in CC rates is suggestive but not yet decisive given current error bars.Final decision
Weak accept