tokens: the Ω 0 increases, the propensity for convection (colored red) within the postshock region clearly decreases. This inhibited convection results in weakened turbulent mass motion within the gain region, thereby reducing the GW amplitude at later times. Figure 6. Spherically averaged anisotropic velocity of the postshock region for the 12 M ⊙ progenitor. Brighter colors correspond to increased convection in the postshock region according to Equation ( 5 ). As rotational velocity increases, convective activity is inhibited. Traced in red is the radius of the PNS. Figure 7. Slices along the equator of the 12 M ⊙ progenitor at each rotational velocity. Colors correspond to the Solberg–Høiland stability criterion, R SH , from Equation ( 6 ). As rotational velocity increases, not only does the convectively stable band in the core grow (seen in blue), but the amount of convection within the postshock region (seen in red) decreases as well. The differences in shock radius evolution between Figure 6 and this figure arise because Figure 6 uses an angular average over the domain, whereas this figure uses equatorial slices. Furthermore, we recast our analysis by focusing on regions within the CCSN that emit GWs. The lower panel of Figure 8 displays the inhibited convective signal with increasing rotation, as the GW signal in the gain region becomes increasingly muted. The typical convective signals in the early postbounce regime are then quickly washed out by the postbounce ring-down of the PNS, as rotation increases. Figure 8. Time domain waveforms for the 20 M ⊙ progenitor. Each panel corresponds to the region from which the GWs are emitted. The large contribution in the top panel indicates the main source of GWs during the accretion phase is from the vibrating PNS. The lower panel displays the inhibited convective signal ∼50–100 ms postbounce that is characteristic of this quiescent phase. Under nonrotating conditions, the shock can grow unstable due to nonradial deformations exciting a vortical-acoustic cycle that leads to the growth of large-scale shock asymmetries, that is, the SASI (Blondin et al. 2003 ; Blondin Mezzacappa 2006 ; Scheck et al. 2008 ; Marek Janka 2009 ). In 2D simulations, the SASI excites large, oscillatory flows along both poles that drive changes in entropy capable of causing postshock convection. It is worth noting in 3D simulations that the SASI can excite “spiral” modes that correspond to nonzero m values (Blondin Shaw 2007 ; Kuroda et al. 2016 ). The high degree of nonlinearity among the hydrodynamic flows, neutrino interactions, and gravitational effects can yield matter flow that is quadrupolar, thereby resulting in GW emission. However, when the shock becomes restricted in the polar direction, due to centrifugal effects, SASI development is inhibited. To quantify the role of SASI, we decompose the shock front into coefficients based on the spherical harmonics, Y l m , according to Equation ( 9 ). Figure 9 illustrates the
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