I am primarily interested in high energy astrophysics, fluid dynamics and computational methods for physics. I currently work with Professor Benedikt Diemer and his collaborators in an attempt to unlock the mechanism that produce magnetic fields in galaxies, which in turn influences cosmic ray propagation.
I worked with Professor Robert Fisher and his group where I led projects on the type Ia supernovae progenitor problem. I was a member of the Gravity Group, led by Professor Ian Vega, at the University of the Philippines where I studied Newtonian and relativistic formulations of dynamical friction for planetary and black hole physics.
My research is a combination of theory and simulations. For my research on galaxies, I use both the ART code by Kravstov et al and RAMSES by Teyssier et al. For my type Ia research, I use the multi-physics massively parallel code FLASH to simulate white dwarf explosions, the general nuclear network code Torch for nucleosynthesis, and the LTE code SuperNu for radiative transfer. Python and Fortran are my languages of choice for post-processing analysis and code development.
I am particularly interested in computational methods used to solve partial differential equations. I am currently writing Jupyter notebooks of solvers that I have developed for classes and personal use.
Magnetohydrodynamic simulations of galaxy formation
Collaborators: Benedikt Diemer (PI), Vadim Semenov, Romain Teyssier
Turbulently-driven flames in ignited white dwarfs
Type Ia supernovae play a central role in astrophysics as standardizable candles used in cosmological distance measurements. However, a full understanding of how these explosions arise in the interior of white dwarfs remain elusive. I currently lead a project where we apply a laboratory-validated turbulence-driven detonation mechanism to three-dimensional full star simulations of near-Chandrasekhar white dwarfs and investigate the observational signatures that arise from these systems.
Collaborators: Chris Byrohl, Robert Fisher (PI), Alexei Poludnenko, Vadim Gamezo
Relevant papers from the literature:
Observable signatures from helium ignited white dwarfs
Helium-ignited double degenerate white dwarf binaries are strong progenitor candidates for normal type Ia supernovae events. In this scenario, the surface helium layer of the primary white dwarf is ignited due to an unstable mass transfer (accretion stream) from its companion. This explosion could send shock waves strong enough to trigger a secondary detonation near the core of the primary as they converge at a point. The products of helium burning in this scenario could provide some insight about the progenitor system through observables like the spectra and its light curve. We are currently investigating possible signatures in observables from this class of helium-ignited binaries.
Collaborators: Daniel Kosakowski, John Gallagher, Alexis Petty, Amy Melhelm, Robert Fisher (PI)
Kosakowski, Ugalino et al (2022) Using 44Ti Emission to Differentiate Between Thermonuclear Supernova Progenitors. https://arxiv.org/abs/2210.10804 (accepted to MNRAS Letters)
Image credit: (left) 3D Hydrodynamical Simulations of Helium-Ignited Double-degenerate White Dwarf Mergers (Roy, Tiwari, Kosakowski, Fisher et al)
Long-term evolution of double degenerate white dwarf mergers
The post-merger evolution of a white dwarf binary could lead to several outcomes, one of which is a type Ia supernovae. This process has been extensively studied through simulations that invoke the alpha viscosity model as the primary mechanism for momentum transfer across the remnant disk. This viscous transfer converts differential shear into local heating, which in turn transforms the initially compact remnant into a 'puffier' system whose size is close to a red giant.
However, fully MHD simulations of these post-merger remnants suggest that the magnetorotational instability (MRI) that is driven by MHD turbulence in the disk lead to the formation of strongly magnetized winds and jets. At later times (20,000 s ~ 0.2 day), a more compact core was observed contrary to results from pure hydrodynamical simulations of this system. In this project, we aim to perform a large-parameter survey of simulations that consider both the alpha disk and the fully MHD models where we compare the energetics of the remnant throughout its evolution.
Relevant papers from the literature:
The viscous evolution of white dwarf merger remnants (Schwab et al)