Probing the early universe

The first generation of stars, dubbed Population III, formed from gas devoid of metals. I'm designing and implementing new photometric methods to search for Pop III and other extremely metal poor galaxies.

Gravitational lensing makes this especially exciting: it magnifies intrinsically faint and sometimes small sources that would otherwise be far out of reach of normal observations. By selecting a population-level sample of metal-poor and Pop III candidates, we can better understand the first chemical enrichment of the universe and how metallicities evolved over time.

Curious? Check out my talk linked below!

A key question in high-z astronomy is at what stage of their evolution galaxies were clumpy. I'm developing selection methods to find galaxies stretched into arcs, where intense magnification makes individual clumps and star clusters visible. This strictly requires lensing: star clusters in high redshift galaxies are normally far smaller than even JWST can resolve, but strong magnification stretches them out until they come into view on spatially resolved scales.

A similar approach can find individual stars in high redshift galaxies. When a star crosses a caustic and is microlensed by stars in the cluster, it can be magnified thousands of times. This lets us observe individual stars in galaxies from z ~ 1 to z ~ 6.

VENUS is a JWST treasury program led by Seiji Fujimoto and Dan Coe, with more than 150 members worldwide. In Cycle 4 it images 60 massive lensing clusters with NIRCam in 10 filters, using each cluster as a natural magnifying glass, and Cycle 5 adds repeat imaging and NIRSpec spectroscopy. The science spans the earliest galaxies, star clusters, and black holes, down to individual lensed stars and supernovae.

I'm a member of the VENUS data working group, where I work on image data processing, highly magnified sources, enrichment, and MSA target selection for the NIRSpec spectroscopy.