Beginning in October, 2017, I will be working at Lawrence Livermore National Laboratory as a post-doctoral scholar. My work will still fall within the larger goal of understanding dark matter astrophysically; however the scale and scope of my research will change. As a graduate student, I study dark matter through observations of merging clusters of galaxies, which are incredibly huge and energetic collisions that occur between objects thousands of times more massive than the Milky Way Galaxy alone. They are composed of hundreds of galaxies all gravitationally bound, but are dominated in mass by dark matter, which I try to understand through observations with huge telescopes.
My post-doctoral research will focus on dark matter at a much smaller scale. There is a prevailing theory that dark matter could be composed of primordial black holes (PBH) or other massive compact objects (MACHOs). This theory was tested once before with a survey of stars in our galaxy. The researchers looked for stars that characteristically changed brightness due to an effect called gravitationally microlensing, where the brightness of a star within the Milky Way characteristically changes over the course of a few weeks to a few years. This occurs because occasionally MACHOs pass between Earth and a distant star with perfect alignment. When this happens the brightness of the background star changes, which allows astronomers to estimate the mass and distance of the MACHO. The original MACHO survey eliminated MACHOs as the source of dark matter for a range of masses below about ten times the mass of the sun. In other words, if dark matter is composed of MACHOs, they must be large, such as black holes. However, our understanding of how black holes form (the end point of stellar evolution), should not have produced enough black holes and definitely not in the early stages of the universe before stars were even formed. Thus, these types of MACHOs (let’s call them IM-MACHOs for intermediate mass-MACHOs), must have formed in the early universe if they are to explain dark matter. PBHs could be one such source.
Recent discoveries by LIGO have stoked new interest in this mass range. Coupling this with advancement of data analysis and telescope capabilities over the past few years, and the time is ripe to take another crack at what the MACHO survey undertook. This time, we will administer new techniques to constrain our understanding of dark matter including the mass range that includes IM-MACHOs.
Outcomes of this project include:
- Constraining the fraction of dark matter in the form of IM-MACHOs
- Measuring the mass function of black holes in the Milky Way
- Developing new data analysis routines to handle temporal-spatial signals
This page is a work in progress