Student: Jacqueline Blaum, Undergraduate Student in Physics, Iowa State University
Research Mentor: Amanda Weinstein
Binned Likelihood Analysis on the Geminga Pulsar
My project involves the use of Fermi Science Tools analysis software in order to perform a binned likelihood analysis on the Geminga pulsar. This is being done in hopes of detecting the Geminga supernova remnant. Using eight years of data, I have selected photon energies from 
300 to 500000 MeV and a region of interest with a radius of 15 degrees centered on the pulsar. I have used the sources within this selection of data, along with Fermi’s background emission models, to create a source model file, in which each source has various parameters that are given either fixed or free values. In order for the source model to converge to the most likely fit of the data, certain parameters have to be freed to change their values during the fit. I also have tried adding an extended source to the model, but, so far, a fit has not converged. Using a model file without the extended source model, I have found a converging fit from which I produced an interesting residual counts map as shown, where the scale is in MeV. In the center, the location of the pulsar, there is a strange pattern of over- and under-subtraction that creates a bright bar shape. I have yet to find an explanation for this odd asymmetry.