%0 Journal Article %T Broadband extended emission in gravitational waves from core-collapse supernovae %A Amir Levinson %A Maurice H. P. M. van Putten %A Guy Pick %J Physics %D 2015 %I arXiv %R 10.1088/0004-637X/812/2/124 %X Black holes in core-collapse of massive stars are expected to surge in mass and angular momentum by hyper-accretion immediately following their formation. We here describe a general framework of extended emission in gravitational waves from non-axisymmetric accretion flows from fallback matter of the progenitor envelope. It shows (a) a maximum efficiency in conversion of accretion energy into gravitational waves at hyper-accretion rates exceeding a critical value set by the ratio of the quadrupole mass inhomogeneity and viscosity with (b) a peak characteristic strain amplitude at the frequency $f_b=\Omega_b/\pi$, where $\Omega_b$ is the Keplerian angular velocity at which viscous torques equal angular momentum loss in gravitational radiation, with $h_{char}\propto f^{1/6}$ at $ff_b$. Upcoming gravitational wave observations may probe this scaling by extracting broadband spectra using time-sliced matched filtering with chirp templates, recently developed for identifying turbulence in noisy time series. %U http://arxiv.org/abs/1509.00404v1