Research

Core-collapse supernovae:

My main research interest currently is modeling hyper-energetic and jet-driven core-collapse supernovae (CCSN), often referred to as hyper novae. I study these events with full 3D dynamical-spacetime general-relativistic magnetohydrodynamic (GRMHD) simulations. For that I am developing the open-source GRMHD code GRHydro as part of the open-source Einstein ToolkitGRHydro uses a finite volume high-resolution shock-capturing based approach together with microphysical finite-temperature equations of state and an approximate neutrino treatment (Leakage scheme). My collaborators and I have recently performed the first 3D GRMHD simulations of rapidly rotating, magnetized stellar collapse. We find that jet-driven explosions that were obtained robustly in previous 2D simulations fizzle in 3D as the jet becomes kink-unstable and fails to explode the core of the star. In the subsequent evolution highly magnetized funnels of material are constantly pumped from the surface of the protoneutron star and produce an advancing shock front in the form of two giant polar lobes. However, this shock front does not manage to become dynamical until the end of our simulation. Even as the two lobes expand along the rotation axis of the star we find that accretion continues in the equatorial region of the core. This is interesting as it may indicate that black-hole formation may be possible in rapidly spinning and magnetized progenitors even if a bipolar explosion takes place, possibly favoring a connection to the collapsar model of long gamma-ray bursts.

Paper: http://iopscience.iop.org/2041-8205/785/2/L29/article
Press release: http://www.caltech.edu/content/supernova-or-not-supernova-3-d-model-stellar-core-collapse
Movie: https://www.youtube.com/watch?v=3sZmvbtIi1I

Electromagnetic counterparts of binary black-hole mergers:

Binary black-hole mergers belong to the most extreme and fascinating events in our universe. Directly observing such events will enable us to gain insight into gravity in a highly dynamical strong field regime. In the case of supermassive black holes, these mergers will not take place in an isolated setting and their interaction with surrounding gas and matter will be a fertile ground for exciting new physics. In my previous research I have worked towards modeling a variety of aspects regarding binary black-hole mergers, with my main focus on connecting their electromagnetic and  gravitational wave signatures.

Horizon geometry in binary black-hole mergers:

In binary black-hole mergers the merger remnant often obtains a kick-velocity due to the anisotropic emission of gravitational waves. During the merger process, however, a sudden deceleration is observed in numerical simulations of these configurations. My collaborators and I have shown that suitably-built quantities defined on inner and outer world-tubes can act as test screens responding to the space-time geometry in the bulk, thus opening the window to a precise cross-correlation approach to probe the space-time dynamics of binary black-hole mergers.

Gravitational wave data analysis:

I have also worked towards improving detection statistics for gravitational wave signals from binary black-hole mergers including spin-effects by utilizing waveform templates covering the inspiral, merger, and ringdown phases. I have investigated the effect of using these (spinning) waveform templates in state-of-the-art data analysis pipelines for the search of gravitational waves from binary black-hole mergers.

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