Research

Broad Research Interests

I consider myself a computational astrophysicist and enjoy using computational approaches to answer astrophysical problems. I see myself continuing to have a computational focus in future work, while being heavily informed by observation. Broadly, my interests lie with dark matter and the history of the universe. Seeking answers to such fundamental questions has led me to having interest in working with dark matter (including my current work with primordial black holes), gravitational waves (especially LISA), black holes, EMRIs/IMRIs, AGNs, galaxy evolution and galactic archaeology, and supernovae. From this same focus, my previous work on massive binary star evolution remains an interest of mine, especially in regards to determining the conditions that impact the fate of massive stars.

My current research is a good intersection of several of these interests. I am working to create a map of the sky seen by LISA if dark matter partially consists of primordial black holes (PBHs).

Current Research

Primordial Black Holes as a Candidate for Dark Matter

The Gravitational Wave Sky from PBHBs

Primordial black holes (PBHs) have been invoked as a component of dark matter, and PBH Binary (PBHB) mergers will produce copious gravitational radiation. The future launch of the Laser Interferometer Space Antenna (LISA), an ESA/NASA gravitational wave observatory set to launch in 2035, will open a new low-frequency band of the gravitational wave sky, one that may include PBHB mergers. Our work focuses on determining what LISA would observe if dark matter consisted partially of PBHs, using a high resolution cosmological n-body simulation, Romulus. Our preliminary work assumes 1% of dark matter consists of PBHs with a single mass spectrum and a binary separation distribution determined by inflationary models. We use LISAcode to calculate the signal-to-noise ratio and sky position uncertainty for each binary PBH, creating a map of the PBH sky seen by LISA. We calculate the three-point correlation function of our sky map to quantify how well PBHs trace large scale structure. This is to determine how well large scale structure within LISA can probe the nature of dark matter, accounting for the small sample size of PBHB mergers LISA would detect and the imprecise sky localization.

Key Figures

Waterfall Plot for PBHB SNRs

A key factor in LISA observations is signal-to-noise ratio. This is a plot of the distance where the binary pair is located in Mpc against their log separation in pc. This plot is shaded based on sky-averaged single-to-noise ratio over the LISA observation time. We require a signal-to-noise ratio of 8 or higher. We use the signal-to-noise calculations to further assess the detectable range of binary separations and to determine how far out in distance these primordial black holes are detectable. We can see out as far as over 450 Mpc for some of these sources.

PBHBs Separations

We use a distribution of binaries and their separations put forth by Nakamura et. al. 1997 to determine the separations for these PBHB to understand where they are in space relative to each other. This accounts for PBH mass, PBH dark matter fraction, and the average distance between PBHs. For this 50 solar mass 1% of dark matter case, above is the overall distribution of log PBH separations in pc and their probabilities. The LISA range is indicated in purple and is 6% of the overall distribution. Combining this with SNR, the detectable range of separtations is highlighted in red and is 3% of the total distribution.

Sample Sky Map

This is a sample sky map of 100 PBHBs, visualized in a galactic projection. Sky location is determined from the dark matter particles in Romulus, so that these PBHBs are seeded as dark matter in space. The predicted LISA merger rates over a 4-year mission time ranges from ~4 to ~110. This map places all of these PBHBs at 100 Mpc way and the errors for this mock catalogue are populated from LISAcode.

Previous Research

Exploring the Origins of Unusual Binary Star Mergers

This research was done during my undergraduate studies at Ohio State with Dr. Marc Pinsoneault and Dr. Rachel Patton. It culminated in my undergraduate thesis which can be accessed through The Ohio State University Knowledge Bank here. This work aimed to determine what was leading to a set of massive binary star mergers to have an unusual core composition post-merger simulated by Binary Population and Spectral Synthesis by individually merging binaries with identical parameters in Modules for Experiments in Stellar Astrophysics. This was especially interesting since core composition is very impactful in the final fate of stars.

A more detailed discussion of what work the project itself entailed can be located in my CV.

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