Supermassive stars are hypothetical objects with masses between 10,000 and 1e8 solar masses that are kept in hydrostatic equilibrium by radiation pressure (unlike ordinary main sequence stars that are powered by nuclear fusion). Even though such a star has never been observed, they are hypothesized to have existed in the very early Universe at high redshifts… Read More
I and collaborators have successfully implemented and tested a multiblock scheme with flux-conservative adaptive mesh refinement (AMR). Multiblocks allow one to cover the simulation domain with multiple curvi-linear grid patches. This enables a greater flexibility in adapting the grid resolution to the problem symmetry. For instance, the gravitational-wave zone or the outer layers of a star exhibit… Read More
I and collaborators have developed a new high-order algorithm for solving the characteristic initial boundary value problem of the Einstein equations. In the characteristic initial boundary value problem of general relativity, the Einstein equations are recast using a particular coordinate system along outgoing nullrays (along the light (or null) cone). The characteristic Einstein evolution system… Read More
I and collaborators have developed and applied the gravitational-wave extraction technique of Cauchy-characteristic extraction (CCE) to simulations of binary black hole mergers, stellar collapse, and binary neutron star mergers to compute the first unambiguous and gauge-invariant GW signal ever extracted for these problems, allowing me to measure, for the first time, the non-linear memory effect in… Read More
