Research

My research in the area of physics is refined to the area of Astrobiophysics. This area of physics examines the affect extraterrestial events (such as nearby supernovae and gamma ray bursts) have on life on Earth. This work is done in association with the KU Astrobiophysics Working Group. My research has expanded into the following areas as a result of this group and our findings.

Cosmogenic Isotopes

Cosmic rays which strike our atmosphere produce showers of secondary particles. Among these particles are neutrons, which aside from other affects, tend to produce isotopic shifts in terrestrial matter. Among these isotopes are rare isotopes which provide details regarding the cosmic ray environment of the Earth throughout history. These isotopes are often examined through ice core and tree core sampling as a means of producing this history. With a detailed history of past events, we are then able to relate these events to possible radiaiton damage within life on Earth.

Cosmogenic Radiation

Two particles which are produced in cosmic ray showers are muons and neutrons. These two sources of ionizing radiation present a threat to life on Earth, especially at high altitudes. Our work has used computational models to find the neutron fluxes in our atmosphere for use finding radiation damage due to particular events. Read more.

Galactic Structure

The Milky Way is a spiral galaxy with spiral arms consisting of locations of greater supernova density. Past work suggested that our location in the galaxy relative to these spiral arms has led to the ice age cycle produced on the Earth. We have found that this is not the case, and the passage of the Earth through the spiral arms is not consistent enough to account for the ice age periodicity. Read more.

Cometary Impacts

The Younger Dryas impact hypothesis suggests that a large cometary airburst occured over the northern hemisphere ~12.9 kyr ago. As this was thought to be an airburst, it did not leave a crater behind. We have developed an alternative means for testing this hypothesis through the use of cosmogenic nuclides which are produced within the comet during its time in interstellar space. Read more.

Effects of Nearby Supernovae

A nearby supernova could have drastic affects to life on Earth. These affects come from cosmogenic radiation as well as ozone depletion leading to a rise in UV damage to life on Earth. Recent research shows that the Earth was exposed to a nearby supernova ~2.5 Myr ago. We hope to better understand what possible affects there could have been to life at this time. Additionally, a nearby supernova could have been the source of currently unexplained past extinction events.