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Dissertation/Thesis Abstract

Understanding the Very High Energy γ-Ray Emission from a Fast Spinning Neutron Star Environment
by Brisbois, Chad Allen, Ph.D., Michigan Technological University, 2019, 150; 22615980
Abstract (Summary)

Pulsars, and their associated pulsar wind nebulae, are factories producing high energy electrons and positrons in our galaxy. The Dragonfly nebula is a Vela-like pulsar wind nebula in the Cygnus region powered by the spin down of PSR J2021+3651. The TeV γ-ray source 2HWC J2019+367 was originally discovered in 2007 by the Milagro Observatory and has been associated with this pulsar. This dissertation presents the first detailed morphological and spectral study of the TeV emission up to the highest photon energies of 2HWC J2019+367. This analysis has identified two sources, the extended source HAWC J2019+368 and the point source HAWC J2016+371. The spectral energy distribution for HAWC J2016+371 is fit by a power law with a flux normalization at 10 TeV of 2.6 ± 0.7 × 10−15 TeV−1 cm−2 s−1 and a spectral index of α = −2.32 ± 0.18. This represents the first independent confirmation of emission from supernova remnant CTB 87 at TeV energies. The γ-ray spectral energy distribution of HAWC J2019+368 significantly prefers a log parabola function, rather than a pure power law. The flux normalization at 10 TeV is 4.05 ± 0.26 × 10−14 TeV−1 cm−2 cm−2, with a spectral index α = −2.02 ± 0.06 and curvature parameter β = 0.29 ± 0.05. The morphology of HAWC J2019+368 is an asymmetric gaussian with semi-major axis a = 0.368° ± 0.021° and eccentricity e = 0.941 ± 0.017. The γ-ray flux measured in this analysis directly corresponds to the measurement of electrons with energies up to ∼ 200 TeV. An electron spectrum is fit to the data for HAWC J2019+368, assuming that the production of γ-rays is due to inverse Compton emission, and shown to be well within the energy budget of PSR J2021+3651. This supports the interpretation of the emission of HAWC J2019+368 being almost entirely due to the electrons and positrons produced by PSR J2021+3651.

Indexing (document details)
Advisor: Huentemeyer, Petra
Commitee: Nemiroff, Robert, Fick, Brian, Sha, Qiuying
School: Michigan Technological University
Department: Physics
School Location: United States -- Michigan
Source: DAI-B 81/3(E), Dissertation Abstracts International
Subjects: Astrophysics
Keywords: Gamma ray, Pulsar, Pulsar wind nebula, VHE
Publication Number: 22615980
ISBN: 9781088385326
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