Undergraduate Research

I was a member of the LIGO/Virgo Collaboration between January 2018 and September 2020, and below are summaries of the various projects I was involved in.

Resonant Excitations in Exotic Compact Objects

National Dutch Institute for Subatomic Physics (Nikhef)
Paper

Exotic Compact Objects (ECOs) are alternatives to the black holes of classical general relativity that may have similar masses and densities with additional features beyond the standard model. For instance, if dark matter is composed of fermionic particles then they may form star-like objects supported by degeneracy pressure: dark matter stars. Boson stars are another potential ECO where a macroscopic object is composed of scalar fields. Gravitational waves (GWs) from presumed binary black hole mergers are now being detected on a regular basis with the Advanced LIGO and Advanced Virgo interferometers. ECOs have not yet been observed, but one method of distinguishing them from classical compact objects predicted by general relativity is studying GW signals as ECOs could leave an imprint upon the GW signal in a variety of ways. One such effect is the presence of resonant excitations spring inspiral. When the gravitational wave frequency during inspiral matches the internal resonant frequency of an ECO, orbital energy will be taken away resulting in a jump in orbital phase relative to point particle phasing. We found that resonances with resultant phase shifts of order unity or larger can be detectable with second-generation interferometers, using Bayesian model selection. We have since applied our analysis method to detections in the GWTC-1 catalog from the first and second observing runs of Advanced LIGO and Advanced Virgo, finding consistency with the binary black hole nature of the sources, and the corresponding publication can be found here.

The Advanced LIGO Timing System

Columbia Experimental Gravity Group (GECo)
Paper

Precise time stamping of gravitational wave (GW) signals is crucial for GW detection using a network of detectors. Reliable and accurate timing between interferometers is essential for many aspects of GW science, one example being the recovery of the source direction. Additionally, timing at different parts of a given detector also needs to be highly synchronized. I contributed to the timing diagnostic system for LIGO, which performs critical checks to ensure the system is robust, fault tolerant, and returns precise results. Prior to LIGO’s third observing run (O3), we modified the pipeline to perform real time, continuous diagnostics with alerts for system failures on two of the timing subsystems. I also performed timing hardware checks at both the LIGO Hanford Observatory and the LIGO Livingston Observatory. Throughout O3, our timing diagnostic results were provided as internal LIGO documents for all open public alert candidates, as well as long term diagnostics for the duration of the run. These results are now publicaly available here.

Low-Latency Algorithm for Multi-messenger Astrophysics (LLAMA) Subthreshold Searches

Columbia Experimental Gravity Group (GECo)
Paper

LLAMA is multi-messenger astrophysics framework and search pipeline that has primarily been used to search for common sources of gravitational waves and high energy neutrinos. LLAMA provides a reliable and flexible framework that can be run for both real-time searches and for offline analyses. Finding neutrino counterparts to GWs is critical for real time multi-messenger science as it can significantly improve the sky localization for further astronomical follow-ups. We adapted the pipeline to find subthreshold coincident candidates using data from LIGO’s third observing run and IceCube.