A MONTE CARLO SIMULATION OF FERMI BLAZARS TO CONSTRAIN THE EXTRAGALACTIC BACKGROUND LIGHT IN THE UNIVERSE

The universe is filled with photons from UV to infrared wavelengths known as the Extragalactic Background Light (EBL) representing all the accumulated radiation in the universe due primarily to star formation processes. The EBL is effective at attenuating gamma rays during their propagation from distant extragalactic sources such as blazars - a form of extremely bright active galaxy. The space-based Fermi gamma ray observatory has now detected 1314 of these objects of known distance over its ten year observing period. The primary goal of this project is to simulate blazar emission and in particular generate the highest energy photon for a number of simulated sources to then be compared with the observed data. As such, it requires the distribution of sources as a function of distance, the luminosity distribution as a function of distance, and the relationship between blazar luminosity and the spectral shape. For the first phase of the project, these observed data were collected and binned to generate the required distributions. A computer simulation was then constructed that samples these distributions via Monte Carlo techniques ultimately generating the highest energy photon from a given source. An equivalent number of sources to that observed are then produced. An attenuation factor from any EBL model can then be applied to each of these simulated highest energy photons and a direct comparison can then be made to the collective highest-energy photons observed by Fermi. A preliminary comparison has already been made to an empirical EBL model that is based entirely on observational data reproducing well the observed distribution from Fermi. Other EBL models present in the literature will also be examined testing their viability.

Additional Abstract Information


Student(s): Alexandra Goodis

Department: Physics and Astronomy

Faculty Advisor: Dr. Sean Scully

Type: Poster

Year: 2019

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