One of the best ways to understand the disk geometry of supermassive black holes (SMBHs) is by analyzing their X-ray spectra, particularly the iron Kα emission line. This emission line typically has two components: a broad, asymmetric part produced in the vicinity of the black hole, and a narrow, symmetric part originating from much greater distances. However, the precise location where the line is emitted remains unclear. Along with my mentor Dr. Abderahmen Zoghbi and collaborator Dr. Jon M. Miller, I have identified the second-ever experimentally verified example of a narrow asymmetric Fe Kα line. This discovery provides evidence that the emitting region of the Fe Kα line is relatively close to the black hole, offering a new tool to probe the inner regions of SMBHs.

The state of quiescence in black hole X-ray binaries (BHXBs) remains poorly understood due to their low luminosities, which make them challenging to detect and study. For my senior thesis, under the guidance of Prof. Charles Bailyn, I focused on the binary system A0620-00, the prototypical quiescent BHXB. Using over 17 years of SMARTS photometric data, the longest dataset available for a quiescent BHXB, I discovered preliminary evidence that the nonstellar emission from A0620-00 originates from both the accretion disk and a second source co-rotating with the companion star around the black hole. Additionally, I confirmed that the orbital period and period decay constant p-dot are consistent with values reported in the literature. This research is ongoing throughout the summer.

The Great Oxygenation Event (GOE) is a major geological event around 2.4 billion years ago when Earth’s atmosphere experienced a substantial and sudden increase in oxygen. The widely accepted explanation attributes this change to cyanobacteria, which evolved to produce oxygen through photosynthesis and rapidly proliferated during the Proterozoic eon. However, there is a lag of at least 400 million years between the evolution of oxygen-producing photosynthesis and the significant rise of atmospheric oxygen, indicating a potential hole in the cyanobacteria theory. I worked with my mentor Dr. Friedemann Freund to develop an alternative non-biological explanation for the sudden influx of oxygen into the atmosphere. We propose a novel chemical mechanism whereby oxygen is released from peroxy-containing rocks during weathering. This chemical mechanism has previously been verified experimentally in the lab. Preliminary order-of-magnitude calculations involving the early global weathering rate, average peroxy content in rocks, and timeframe for the GOE indicate that this peroxy-weathering mechanism is a viable alternative mechanism for how the GOE was caused.

It is well known that the variability of the accretion flow of black holes can be used to probe the black hole’s properties. In my first-year summer of undergrad, I worked with Prof. Charles Bailyn to examine the short-term variability of the non-stellar emission from A0620-00. Minute-timescale variability remains unexplored for all wavelength regimes in A0620-00, and for quiescent black hole binaries more generally. We found that there appears to be quasi-periodic variability on timescales of 30-40 minutes at orbital phases 0.4 < θ < 0.7, but not θ < 0.4. Understanding this dependence on phase will yield insights into quiescent black holes and how mass is accreted in this specific system.

Malaria is a significant health issue in sub-Saharan Africa, where patients often simultaneously suffer from infections with soil-transmitted helminths (STHs), a type of parasitic worm. The role of the gut microbiome during this co-infection is not well understood. During high school, I worked with my mentor, Dr. Alice Easton, to explore the correlations between the gut microbiome, malaria, and STHs using R and QIIME, and applied machine learning to identify key predictors of malarial symptom severity. Our research revealed that malarial infection affects blood cell counts, increases certain immune signaling molecules, and significantly alters the gut microbiome, particularly in children. Surprisingly, we found that changes in gut bacteria were the best predictors of malarial severity, rather than co-infection with STHs.