Kirsten Larson
The College of Wooster

REU program-Summer 2006
Univ. of Wisconsin - Madison
Madison, WI 53706

Research projects of other REU students
klarson08 at wooster dot edu


The Multiwavelength Campaign

We are observing three Blazars with the WIYN 0.9m telescope, the VERITAS gamma ray telescope and the the AMANDA neutrino telescope. Our three sources are Markarian 421, Markarian 501 and 1ES 1959+650. Blazars are a subset of Active Galactic Nuclei (AGN) that emit radiation that ranges from radio to gamma-rays. This emission is thought to be caused by reletivistic jets that are pointed toward us. These jets are powered by a super massive black hole and are also thought to be the cause of a blazar's variability.

There are two theories behind the cause of radiation from TeV Blazars. The leptonic inverse-Compton models seems to explain TeV Blazars well, however there may also be hadronic mechanisms. Detection of neutrinos from these sources would provide evidence for this hadronic mechanism. Due to the possible correlation between TeV photons and neutrinos from pion decay, looking at the blazars during times of gamma-ray flares can increase the probability of detecting neutrino coincidences.

Pion Decay

Production of Neutrinos and Gamma Rays through pion Decay

In hadronic blazar models both gamma-rays and neutrinos are emitted during pion decay. The blazar's jets accelerate protons, which produce pions by interacting with matter and ambient photons. The neutral pions then decay into gamma-rays, while the charged pions decay into neutrinos. If this model is correct, focusing on periods of high TeV activity called "flaring" can enhance detection of neutrinos. During flares, fluxes are high for only a short amount of time and this variability helps discriminate the background of atmospheric neutrinos. In order to preserve the statistical purity of the sample until the analysis has been fully optimized, we are not presenting any neutrino data.

Instead of confining a search to specific flares, we could take longer time periods and study the correlation between neutrino events and high-flux behavior in gamma-rays. We have analyzed the probability of gamma-ray flaring comparing preliminary long-term VERITAS data with corresponding optical observations.


Optical Data

TeV Data



Poster for the TeV Conference 2006 presented by Matthew Bayer

Poster for the AAS Conference 2007 presented by Kirsten Larson

My Final Presentation

Analysis Team

Advisor: Teresa Montaruli - Assistant Professor at University of Madison-Wisconsin and University of Bari

Matthew Bayer - University of Madison-Wisconsin

David Steele - Adler Planetarium / VERITAS Collaboration

Useful links

IceCube Homepage

AMANDA Homepage