Research Interests

I'm interested in cosmology especially the dark energy.

The equations of general relativity predict a Universe that cannot remain static - it must either expand forever or collapse in on itself. Einstein didn't like this result and "fixed" it by introducing a "fudge factor" called the cosmological constant. Edwin Hubble's observations of Cepheid variables allowed him to calibrate distances to far away galaxies. Observations of the shifts in spectral lines from the galaxies can give their radial velocities. When Hubble examined the redshift data and his distances he found a relationship - they were roughly proportional. He found that the Universe was actually expanding. A Universe expanding at a constant rate didn't need a cosmological constant. That was 1929.

In 1998, spectral and photometric observations of type Ia supernovae - standard candles that play the same role that the Cepheids did for Hubble - indicated that the expansion of the universe is not constant - it's accelerating. That observation can be explained by introducing a form of energy with a negative pressure - the dark energy.

What the actual form of the dark energy is still an open question. One possible answer is that its Einstein's greatest blunder rearing its head again - a small non-zero cosmological constant. Simply space has some intrinsic energy density. Field theory predicts a cosmological constant that is 120 orders of magnitude different than observations. That isn't right. Some SUSY models get closer by predicting a zero cosmological constant. That isn't right either. No model in particle physics seems to give you a natural way to get the small positive value of lambda without tinkering - fine-tuning. There is lots of theoretical work to be done.

Might the cosmological constant be something different - a dynamic field called quintessence? Maybe general relativity itself is wrong on very large length scales. There is a way to tell. Projects are underway to measure the equation of state of the dark energy and test general relativity more thoroughly. These projects need new facilities, equipment, even experimental techniques, which need to be developed. The science that comes out of this effort will tell us a great deal and demand that we better our understanding of the Universe we live in.

Projects

I've worked with Professor Linda French at Illinois Wesleyan University on the photometry of primitive objects. The group has observed several C and D type asteroids. Of particular interest are the Damocloids. The Damocloids are a group of asteroids with highly eccentric and inclined orbits, similar to those of Halley Family Comets. Several Damocloids have already exhibited cometary activity and the dissimilarity of their orbits and Jupiter Family Comet orbits lend credence to the hypothesis. Broadband photometry of Damocloid nucleii can provide valuable surface information and possibly insight on HFC nucleii. We observed comet C/2002 CE10(LINEAR) near opposition but photometry of the nucleus was not possible as the object had developed coma during this period.

The group has also examined several Trojan asteroids. We are interested in the solar phase angle relation for these objects, and if they exhibit the same kind of opposition effect as main belt asteroids.

I am responsible for the image reduction and analysis of the objects, and was part of a one week observing run at the 0.9m at CTIO during October 2003.

Honors Thesis

Thesis Defense Presentation