Axisymmetric General Relativistic Simulations of the Accretion-Induced Collapse of White Dwarfs
Phys. Rev. D. 88, 044012
- Gravitational Wave Signal Data -
| The accretion-induced collapse (AIC) of a white dwarf (WD) may lead to the formation of a protoneutron star and a collapse-driven supernova explosion. This process represents a path alternative to thermonuclear disruption of accreting white dwarfs in Type Ia supernovae. In the AIC scenario, the supernova explosion energy is expected to be small and the resulting transient short-lived, making it hard to detect by electromagnetic means alone. Neutrino and gravitational-wave (GW) observations may provide crucial information necessary to reveal a potential AIC. Motivated by the need for systematic predictions of the GW signature of AIC, we present results from an extensive set of general-relativistic AIC simulations using a microphysical finite-temperature equation of state and an approximate treatment of deleptonization during collapse. Investigating a set of 114 progenitor models in axisymmetric rotational equilibrium, with a wide range of rotational configurations, temperatures and central densities, and resulting white dwarf masses, we extend previous Newtonian studies and find that the GW signal has a generic shape akin to what is known as a ``Type~III'' signal in the literature. Despite this reduction to a single type of waveform, we show that the emitted GWs carry information that can be used to constrain the progenitor and the postbounce rotation. We discuss the detectability of the emitted GWs, showing that the signal-to-noise ratio for current or next-generation interferometer detectors could be high enough to detect such events in our Galaxy. Furthermore, we contrast the GW signals of AIC and rotating massive star iron core collapse and find that they can be distinguished, but only if the distance to the source is known and a detailed reconstruction of the GW time series from detector data is possible. Some of our AIC models form massive quasi-Keplerian accretion disks after bounce. The disk mass is very sensitive to progenitor mass and angular momentum distribution. In rapidly differentially rotating models whose precollapse masses are significantly larger than the Chandrasekhar mass, the resulting disk mass can be as large as ~0.8 solar masses. Slowly and/or uniformly rotating models that are limited to masses near the Chandrasekhar mass produce much smaller disks or no disk at all. Finally, we find that the postbounce cores of rapidly spinning white dwarfs can reach sufficiently rapid rotation to develop a gravito-rotational bar-mode instability. Moreover, many of our models exhibit sufficiently rapid and differential rotation to become subject to recently discovered low-E_rot/|W|-type dynamical instabilities. |
Below we provide gravitational wave signature data for our model set discussed in this paper.
For each model we compute and make available here the gravitational wave emissions from matter motions via the slow-motion, weak-field quadrupole approximation. Details on the extraction formalism can be found in the paper.
We also provide the time evolution of the central density -- this quantity is useful to grahically determine the time of core bounce for a given model.
A recent review on the overall gravitational-wave signature of stellar collapse and collapse-driven
supernovae can be found in Ott 2009.
All gravitational-wave data files are in gzipped plain text ASCII format with two columns: time (in seconds) and h_+ at an assumed source distance of 10 kpc and as seen by an equatorial observer. All central density data files
are in gzipped plain text ASCII format with two columns: time (in seconds) and rho_c in g/cm^3.
Please let us know if you have any questions or comments concerning the data provided here: 