User:Kjizel

Personal Info
My real name is Kellen Murphy. I have a B.S. in Physics and Mathematics from Otterbein College, in Westerville, OH. I also have an M.S. in Physics from Ohio University; where I am presently a Ph.D. candidate in astrophysics. My field of research is observational cosmology.

Research
I work with the Ohio University Astrophysical Institute in the field of observational astrophysics. My specialty is the using weak gravitational lensing to study the largest structures in the universe: galaxy clusters. My advisor is Doug Clowe.

When the light from distant galaxies passes through a galaxy cluster, the light is bent by all the (luminous, as well as "dark") matter in the cluster, as per Albert Einstein's General Theory of Relativity. This provides us with a method of determining how much "stuff" is out there in the universe by analyzing how much the galaxies' images are distorted. This is a difficult task since we are attempting to discern a minute change in the ellipticity distribution of galaxies in a given sample, and since we cannot see the original, unlensed galaxies, we must rely on the fact that on average, the galaxies should have NO net ellipticity (since the number of galaxies that are elliptical along one axis placed on the sky should be identical to the number elliptical along any other axis given an isotropic distribution of galaxies in the universe).

In other words, only by measuring the the shapes of a large number of galaxies can we tell by how much the image of each individual galaxy is "sheared" by the mass in the cluster.

I specifically study how the amount of shearing on a galaxy is dependent on the distance between the observer and the source, by including photometric redshift information in our analysis. By grouping together galaxies at different distances, we are able to look at slices of the night sky, and can use tomographic techniques to perform more robust analysis of clusters. It is expected that by using weak lensing tomography, we would be able to further constrain our understanding of the universe by pinning down the dark energy equation of state; since dark energy makes us 70% of what's "out there," this is a very sought-after result.