Date of Award
2023
Document Type
Open Access Dissertation
Degree Name
Doctor of Philosophy in Physics (PhD)
Administrative Home Department
Department of Physics
Advisor 1
Petra Huentemeyer
Committee Member 1
Brenda Dingus
Committee Member 2
Brian Fick
Committee Member 3
David Nitz
Abstract
Since Victor Hess's groundbreaking detection of cosmic rays in the Earth's atmosphere in 1912, the origins of these charged particles have remained an enduring mystery. Recent studies suggest that these cosmic rays are accelerated beyond Peta electronvolts by powerful astrophysical sources within our own galaxy. While the cosmic rays themselves are being deflected in all directions by magnetic fields, the gamma rays produced by them, being electrically neutral, travel to the observer in a straight line. They carry crucial information, allowing us to trace cosmic-ray accelerators within our galaxy. The High Altitude Water Chrenkov (HAWC) Observatory, located on the slopes of the Sierra Negra volcano near Puebla, surveys the gamma-ray sky with a duty cycle of over 95\%. A sensitivity to gamma rays ranging from about 100 GeV to beyond 100 TeV, coupled with a 2-steradian instantaneous field of view, makes HAWC one of the premier observatories for studying the most energetic galactic gamma-ray sources. The gamma-ray source eHWC J1825-134, passing the field of view of HAWC at a zenith angle of $32^{\circ}$, is located in the brightest region above 50~TeV in the HAWC data set. This region contains several astrophysical objects, including three pulsar wind nebulae powered by fast-spinning pulsars, a young star cluster, a gamma-ray binary system, and four supernova remnant shells. All these objects are capable of accelerating charged particles and contributing to the cosmic rays detected at Earth. This dissertation focuses on in-depth morphological and spectral studies within the eHWC J1825-134 region. Through a multi-source maximum likelihood analysis, we are able to separate gamma-ray emissions from different sources: the binary system LS 5039, PSR J1826-1254 and its associated pulsar wind nebulae, and the emission source HAWC J1825-134 which is either associated with PSR J1826-1334 or a young star cluster. The gamma-ray sources LS 5039 and HAWC J1825-134 are PeVatron candidates emitting to about 200 hundred TeV at least. Additionally, two TeV halo candidates surround PSR J1826-1334 and PSR J1813-1246.
Recommended Citation
Huang, Dezhi, "Tracing the Most Powerful Galactic Cosmic-ray Accelerators with the HAWC Observatory", Open Access Dissertation, Michigan Technological University, 2023.