The Mass Density of Black Holes in the Universe
with Maya Fishbach
See the paper here.
Using population fits to GWTC-3 data, I developed a model for the mass density in stellar mass black holes that merge. This model begins with the star formation rate, since black holes come from stars, and I apply a metallicity-dependent efficiency to account for the fraction of all stars that become black holes that merge. I also account for the time delay between when a star forms and when it eventually partakes in a BBH merger.
By fitting the parameters in this model to the GTWC-3 data, we found that BBHs preferentially form in low-metallicity environments. In addition, there is a preference for short delay times, indicating it does not take long for a star to form, evolve, die, and merge with another.
By studying the mass density, we can directly compare to other objects in the universe. We found that it is possible that there could be more mass in merging black holes than in living stars >10 solar masses. There was also more mass in merging black holes than in the young supermassive black holes before the universe was 1 Gyr old.
Detecting Extreme Scattering Events in the VAST Survey
with Bryan Gaensler
Extreme scattering events were discovered over 30 years ago but their cause is still unknown. Characterized by dips in flux in radio bands, it is thought that their origin may be galactic clouds occulting galaxies however more data is needed to confirm this. I wrote python code that scans VAST light curves and gives them a score indicating the possibility of an extreme scattering event being observed.
White Dwarfs with Infrared Excess with JWST
with Dr. Harvey Richer and Dr. Jeremy Heyl
In preparation for an approved JWST proposal to look for infrared excess around white dwarfs, I created a catalog of white dwarfs in the approved field from Hubble Space Telescope data. Looking for infrared excess means you are looking for white dwarfs that have more infrared radiation than expected. This could be caused, for example, by a disk made up of destroyed planets orbiting around the white dwarf. I simulated the expected JWST magnitudes based on Hubble data and white dwarf models. Thus, if the JWST magnitudes are higher than projected for any white dwarf, an infrared excess will be detected.
Image Credit: Gemini Observatory Illustration by Jon Lomberg
