Correlated Gravitational Wave and Neutrino Signals from General-Relativistic Rapidly Rotating Iron Core Collapse
We present results from a new set of 3D general-relativistic hydrodynamic simulations of rotating iron core collapse. We assume octant symmetry and focus on axisymmetric collapse, bounce, the early postbounce evolution, and the associated gravitational wave (GW) and neutrino signals. We employ a finite-temperature nuclear equation of state, parameterized electron capture in the collapse phase, and a multi-species neutrino leakage scheme after bounce. The latter captures the important effects of deleptonization, neutrino cooling and heating and enables approximate predictions for the neutrino luminosities in the early evolution after core bounce. We consider 12_⊙ and 40_⊙ presupernova models and systematically study the effects of (i) rotation, (ii) progenitor structure, and (iii) postbounce neutrino leakage on dynamics, GW, and, neutrino signals. We demonstrate, that the GW signal of rapidly rotating core collapse is practically independent of progenitor mass and precollapse structure. Moreover, we show that the effects of neutrino leakage on the GW signal are strong only in nonrotating or slowly rotating models in which GW emission is not dominated by inner core dynamics. In rapidly rotating cores, core bounce of the centrifugally-deformed inner core excites the fundamental quadrupole pulsation mode of the nascent protoneutron star. The ensuing global oscillations (f ~700-800 Hz) lead to pronounced oscillations in the GW signal and correlated strong variations in the rising luminosities of antineutrino and heavy-lepton neutrinos. We find these features in cores that collapse to protoneutron stars with spin periods ≾ 2.5 ms and rotational energies sufficient to drive hyper-energetic core-collapse supernova explosions. Hence, joint GW + neutrino observations of a core collapse event could deliver strong evidence for or against rapid core rotation. Our estimates suggest that the GW signal should be detectable throughout the Milky Way by advanced laser-interferometer GW observatories, but a water-Cherenkov neutrino detector would have to be of near-megaton size to observe the variations in the early neutrino luminosities from a core collapse event at 1 kpc.
Additional Information© 2012 American Physical Society. Received 21 April 2012; revised 20 June 2012; published 13 July 2012. We are happy to acknowledge helpful exchanges with Y. Chen, C. Cutler, L. Dessart, I. Hawke, W. Kastaun, F. Löffler, C. Meakin, P. Mösta, N. Stergioulas, P. Ajith, and D. Tsang. This work is supported by the National Science Foundation under grant numbers AST-0855535, OCI-0905046, and OCI-0941653, and by the Sherman Fairchild Foundation. We wish to thank Chris Mach for support of the group servers at TAPIR on which much of the code development and testing was carried out. Results presented in this article were obtained through computations on the Caltech compute cluster "Zwicky" (NSF MRI award No. PHY-0960291), on the NSF XSEDE network under grant TG-PHY100033, on machines of the Louisiana Optical Network Initiative under grant loni_numrel07, and at the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the US Department of Energy under contract DE-AC03-76SF00098.
Published - PhysRevD.86.024026.pdf
Submitted - A9R71C7.pdf