Studying the 3D shapes of galaxies involves modeling lots of ellipsoids and understanding how they project to a surface, like the sky.

My Research

I am an observational cosmologist. Matter in the universe, and therefore galaxies, forms what we call a large-scale structure. It basically looks like a giant sponge – made up of strands and sheets of matter, with large voids that contain almost no matter. There are several statistics that we use to quantify this structure. They basically measure how “clumpy” the distribution of galaxies are.

DESI needs to measure these very precisely in order to distinguish between different models of dark energy, which means that we have to consider MANY difference sources of systematic errors. My work is exploring one of these sources.

The types of galaxies I look at are basically 3D ovals, and DESI is more likely to observe a galaxy if its long axis is pointed at us. This is because its light is more concentrated on the sky and it appears to have a higher surface brightness. This is a problem because the orientations of galaxies are ALSO aligned with the matter density that we are trying to measure.


Here is how I would summarize my work to different audiences:

Kindergartener

I use a telescope to look very far away at big clumps of stars. We’re exploring big mysteries about the universe. We don’t know why, but it’s getting ripped apart very quickly and we’re all going to die.

High Schooler

The universe is expanding, and its expansion is increasing. We’re not sure what force is driving this, but we call it dark energy. We’re using a telescope to observe 30 MILLION galaxies and making the most detailed map of the universe yet! I help measure the statistics which quantify how galaxies are distributed and how that distribution has changed over time. This will help us better understand what’s up with dark energy.

Astronomy Undergraduate Student

I’m helping with a spectroscopic galaxy survey, DESI. My project is measuring the correlation between galaxy shapes and the underlying density field. This is important because DESI’s target selection is dependent on galaxy orientation, which is tied to said density field.

Cosmologist

I’m measuring the projected shape-density correlation of Luminous Red Galaxies in DESI’s Legacy Imaging Survey. I’m also modeling the net polarization of LRGs due to DESI’s fiber magnitude-based selection. These effects combine to create a systematic bias in DESI’s measurement of the RSD quadrupole. We’re interpreting the IA signal via a suite of cosmological n-body simulations, AbacusSummit, and a linear tidal model.