Spontaneous scalarization as a new core-collapse supernova mechanism and its multimessenger signals

We perform multidimensional core-collapse supernova (CCSN) simulations in a massive scalar-tensor theory for the first time with a realistic equation of state and multienergy neutrino radiation. Among the set of our models varying the scalar mass and the coupling strength between the scalar and gravitational fields, a particular model allows for recurrent spontaneous scalarizations (SSs) in the protoneutron star (PNS). Each SS induces the PNS collapse and subsequent bounce, from which devastating shock waves emanate and eject the PNS envelope. The explosion energy can easily exceed $\mathcal{O}({10}^{51})\mathrm{erg}$. This study reveals new aspects of SS as the explosion mechanism of CCSNe. We also discuss its characteristic multimessenger signals: neutrinos and gravitational waves.

Figure 1

Overall evolution feature of all models. Panel (a): the maximum rest-mass density ${\rho }_{\max }$; (b): PNS rest mass $M_{\mathrm{PNS}}$ and central lapse function ${\alpha }_{\mathrm{c}}$; (c): central scalar field ${\phi }_{\mathrm{c}}$ and 2-norm of the Hamiltonian constraint $||\mathcal{H}|{|}_2\times {10}^{-4}$; (d): averaged shock radius $R_{\mathrm{s}}$ (dashed) and diagnostic explosion energy $E_{\exp }$ (solid). The color represents each model listed in panel (a).

Figure 2

Various neutrino profiles as functions of $t_{\mathrm{pb}}$. The right column shows a magnified view at the first SS for $B20m11$. From top: the neutrino luminosity $L_{\nu }$; mean energy $⟨{\epsilon }_{\nu }⟩$; and neutrino detection rate $\mathrm{\Gamma }$ of IC and HK, respectively. All plots assume a source distance of $D=10\mathrm{kpc}$. The color and line style represents the model and neutrino species, respectively, shown in the top panels.

Figure 3

Panel (a): the scalar waveform $\sigma \equiv r_{\mathrm{ex}}\phi$ extracted at two different radii $r_{\mathrm{ex}}={10}^8$ (black line) and $5\times {10}^8\mathrm{cm}$ (red); (b): matter origin GWs $D{h}_{+}$; (c): spectrogram $\tilde{h}(F,t)$ of $h_{+}$. Here we assume a source distance of $D=10\mathrm{kpc}$. Panel (a) shows $\sigma$ of $B20m14$ and $B20m11$, where $\sigma$ of $B20m11$ is multiplied by 100. Panels (b,c) show only of $B20m11$.

Figure 4

Characteristic strain of matter origin GWs (thick) overplotted by the sensitivity curves of the current- and third-generation GW detectors (thin): advanced LIGO, advanced VIRGO, KAGRA, Einstein Telescope, and Cosmic Explorer. We assume a source distance of 10 kpc.