We propose a two year program to RE-analyze comptel data in search for evidence of polarization in both transient sources and in brighter steady sources. We propose to pursue this work because of…

This federal contract award, with ID NNX15AI70G, was granted by the Shared Services Center (SSC) of a civilian federal agency to the University System of New Hampshire (UNH), through its University of New Hampshire division operating as the Office of Sponsored Research.

The two-year, $218,988.63 grant funds a program to re-analyze data from the Compton Telescope (COMPTEL) instrument on the Compton Gamma Ray Observatory (CGRO) satellite, in search of evidence of polarization in both transient and steady gamma-ray sources. The analysis will utilize high-fidelity GEANT4 simulations and updated analysis tools to build on earlier inconclusive results. This work is expected to contribute to the understanding of the polarization properties of gamma-ray sources like gamma-ray bursts, solar flares, the Crab Nebula, and Cygnus X-1. The contract does not have a set-aside designation.

We propose a two year program to RE-analyze comptel data in search for evidence of polarization in both transient sources and in brighter steady sources. We propose to pursue this work because of the heightened interest in high energy polarimetry, the recognition that some high energy sources may be highly polarized (thus improving our chances of a making useful measurements), and the ready availability of modern computing resources that provide the ability to carry out more comprehensive simulations in support of the analysis. The only significant work done to date with regards to comptel polarimetry was published almost 20 years ago and used a simplified mass model of comptel for simulating the instrument response. Estimates of the minimum detectable polarization (MDP) near 1 MEV included 30% for a two-week observation of the crab, as low as 10% for bright grbs, and as low as 10% for bright solar flares. The data analysis performed at the time led to inconclusive results and suggested some unknown systematic error. We contend that a self-consistent analysis will be feasible with high fidelity simulations, simulations that were not easily generated 20 years ago. Our analysis will utilize the latest GEANT4 simulation tools in conjunction with a high-fidelity mass model of the comptel instrument, and incorporate updated analysis tools originally developed by the comptel collaboration. Given the nine years of comptel data, we expect that this work will likely add to our understanding of the polarization properties of transient sources (grbs and solar flares), as well as brighter steady sources, such as the crab and CYG X-1.