Maximum Likelihood Compton Polarimetry with the Compton Spectrometer and Imager

• Published in: The Astrophysical journal Vol. 848; no. 2; pp. 120 - 126
• Main Authors: Lowell, A. W., Boggs, S. E, Chiu, C. L., Kierans, C. A., Sleator, C., Tomsick, J. A., Zoglauer, A. C., Chang, H.-K., Tseng, C.-H., Yang, C.-Y., Jean, P., Ballmoos, P. von, Lin, C.-H., Amman, M.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 20.10.2017; IOP Publishing
• Subjects: ASTROPHYSICS; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPTON SPECTROMETERS; DATA ANALYSIS; ENERGY RESOLUTION; GAMMA RADIATION; Gamma rays; Histograms; instrumentation: polarimeters; Maximum likelihood method; MAXIMUM-LIKELIHOOD FIT; methods: data analysis; POLARIMETERS; POLARIMETRY; POLARIZATION; SCATTERING; Scattering angle; techniques: polarimetric; TELESCOPES
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/aa8ccd

Astrophysical polarization measurements in the soft gamma-ray band are becoming more feasible as detectors with high position and energy resolution are deployed. Previous work has shown that the minimum detectable polarization (MDP) of an ideal Compton polarimeter can be improved by ∼21% when an unbinned, maximum likelihood method (MLM) is used instead of the standard approach of fitting a sinusoid to a histogram of azimuthal scattering angles. Here we outline a procedure for implementing this maximum likelihood approach for real, nonideal polarimeters. As an example, we use the recent observation of GRB 160530A with the Compton Spectrometer and Imager. We find that the MDP for this observation is reduced by 20% when the MLM is used instead of the standard method.