A NEW MULTI-DIMENSIONAL GENERAL RELATIVISTIC NEUTRINO HYDRODYNAMICS CODE OF CORE-COLLAPSE SUPERNOVAE. III. GRAVITATIONAL WAVE SIGNALS FROM SUPERNOVA EXPLOSION MODELS

Abstract

We present a detailed theoretical analysis of the gravitational-wave (GW)\nsignal of the post-bounce evolution of core-collapse supernovae (SNe),\nemploying for the first time relativistic, two-dimensional (2D) explosion\nmodels with multi-group, three-flavor neutrino transport based on the\nray-by-ray-plus approximation. The waveforms reflect the accelerated mass\nmotions associated with the characteristic evolutionary stages that were also\nidentified in previous works: A quasi-periodic modulation by prompt postshock\nconvection is followed by a phase of relative quiescence before growing\namplitudes signal violent hydrodynamical activity due to convection and the\nstanding accretion shock instability during the accretion period of the stalled\nshock. Finally, a high-frequency, low-amplitude variation from proto-neutron\nstar (PNS) convection below the neutrinosphere appears superimposed on the\nlow-frequency trend associated with the aspherical expansion of the SN shock\nafter the onset of the explosion. Relativistic effects in combination with\ndetailed neutrino transport are shown to be essential for quantitative\npredictions of the GW frequency evolution and energy spectrum, because they\ndetermine the structure of the PNS surface layer and its characteristic g-mode\nfrequency. Burst-like high-frequency activity phases, correlated with sudden\nluminosity increase and spectral hardening of electron (anti-)neutrino emission\nfor some 10ms, are discovered as new features after the onset of the explosion.\nThey correspond to intermittent episodes of anisotropic accretion by the PNS in\nthe case of fallback SNe. We find stronger signals for more massive progenitors\nwith large accretion rates. The typical frequencies are higher for massive\nPNSs, though the time-integrated spectrum also strongly depends on the model\ndynamics.\n