Non-Monotonic Rotation Imprint on Time-Integrated Neutrino Spectral Moments in a 15\,$M_\odot$ Core-Collapse Supernova Sequence

TL;DR

This study analyzes the early neutrino signals from three 3D supernova models with varying rotation speeds, revealing a non-monotonic, opposite spectral shift response to rotation that is consistent across multiple lines of sight.

Contribution

It provides the first detailed analysis of how different rotation rates affect neutrino spectral moments in a specific supernova model sequence, highlighting a non-monotonic response.

Findings

Fast rotation causes softer, more-pinched neutrino spectra.

Slow rotation induces a weak shift toward harder spectra.

The rotation imprint is consistent across all lines of sight during early accretion.

Abstract

We study the early post-bounce neutrino signal of the published Garching $15\,M_\odot$ rotating core-collapse supernova (CCSN) sequence consisting of non-rotating (NR), slowly rotating (SR, $\Omega_0=0.5$ rad\,s$^{-1}$), and fast-rotating (FR, $\Omega_0=150$ rad\,s$^{-1}$, artificially boosted ${\sim}300{\times}$) three-dimensional models. We present a new analysis of these publicly available simulation data; no new simulations were performed. Our central result, for this specific model sequence, is that SR and FR shift the integrated spectral moments in \emph{opposite directions} relative to NR: FR drives the spectra toward softer, more-pinched states, while SR moves them weakly toward harder, less-pinched states. Placed in a spectral-shift plane $(\Delta\langle E\rangle_L,\,\Delta\alpha_L)$, NR sits at the origin, and SR and FR occupy \emph{diagonally opposite quadrants}, making the non-monotonic response immediately visible as an anti-correlation in two spectral dimensions simultaneously. The focus is the accretion interval $t_{\rm pb}=0.05$--$0.30$\,s, where the rotation imprint is strongest. Quantitatively, fast rotation produces $\Delta\langle E_{\nu_e}\rangle_L=-0.513$\,MeV and $\Delta\alpha_{\nu_e}=+0.161$, with corresponding shifts $\Delta\langle E_{\bar\nu_e}\rangle_L=-0.440$\,MeV and $\Delta\alpha_{\bar\nu_e}=+0.173$; the SR shifts are an order of magnitude smaller and in the opposite sense. The fast-rotation signature is coherent across all $15\,488$ lines of sight and is established during early accretion. With only three models from a single progenitor family, this result is a phenomenological characterization of one published sequence and a suggestive indication of a non-monotonic, possibly strongly nonlinear, rotational response within this sequence; the functional form and generality of the dependence on $\Omega_0$ remain unconstrained.