Congrats to Manas for passing his thesis proposal with flying colors!
Discontinuous Galerkin method for simulating gravitational waves from merging black holes with extreme masses by Manas Vishal
January 20, 2023 – CSCDR (Textiles 105) –– 10:00am. With the detection of first gravitational waves in 2015 by Laser Interferometer Gravitational wave Observatories (LIGO), which was recently awarded a Nobel prize for this discovery, there is an urgent need of more theory-based template waveforms covering the space of plausible signals. The upcoming space-borne detector Laser Interferometer Space Antenna (LISA) is primarily sensitive to Extreme Mass Ratio Inspirals (EMRI) where the mass ratio between two black holes is higher than 10^5. LIGO uses a method known as matched filtering, where the data analysis pipeline tries to match the incoming signals with the existing waveforms simulated from Numerical Relativity (NR) or other numerical techniques. NR is only useful to model systems where the mass ratio is less than 50 as the problem becomes computationally expensive for larger ratios. Hence, there is a need to use a different method to simulate EMRI systems. In this talk, I will describe a Discontinuous Galerkin (DG) method for simulating waveforms from EMRI systems. We reduce the Teukolsky equation, which governs the behavior of EMRIs, to a set of coupled 1+1D wave equations and apply the DG method to it with a delta source term, acting like the secondary black hole in an EMRI system. Unlike other numerical schemes, our DG method can exactly incorporate the point particle behavior of the smaller black hole in the form of a delta function. Due to the spectral convergence properties of the scheme, our efficient method generates highly accurate waveforms in very short time as compared to other methods. We report on the preliminary results of evolving a scalar radiation field. We verify our computation by computing Price tail power laws and energy fluxes. As part of my thesis work, we will be extending the code to solve the full s=-2 Teukolsky equation to generate gravitational waves from the EMRI systems, which in turn will help in building up the template waveform bank and surrogate models for LISA data analysis.