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Exotic binaries in Galactic globular clusters: identification, classification, and their formation

  • Author / Creator
    Zhao, Yue
  • Globular clusters (GCs) are dense and massive stellar populations, which provide a unique environment where the high stellar density facilitates frequent dynamical encounters, creating many exotic binaries. These exotic binaries generally have short orbits and often harbour compact objects, namely neutron stars, black holes, and white dwarfs. With the unprecedented sensitivity and angular resolution of the Chandra X-ray Observatory, GCs are found to host an overabundance of X-ray binaries. This thesis contains chapters that identify and classify exotic binaries in multiple GCs and presents their relation to cluster dynamics, incorporating X-ray, UV, optical, and radio observations. In the GC M3 (NGC 5272), we discovered 16 X-ray sources within the half-light radius where the second brightest source (M3-CX2) is a newly discovered low-mass X-ray binary candidate. In a study of NGC 6397, we incorporate deep radio imaging observations from the MAVERIC radio survey and find a strong "hidden" millisecond pulsar candidate. A deep observation of M30 reveals 10 new X-ray sources within its half-light radius and suggests a difference between the radial distributions of bright and faint X-ray sources. Finally, a census of radio sources in multiple GCs indicates that they are likely a mixture of millisecond pulsars (the numbers of which, per cluster, scale with the rate of stellar encounters in each cluster) and quiescent black hole binaries (which do not show a simple scaling with the number of stellar encounters per cluster).

  • Subjects / Keywords
  • Graduation date
    Fall 2021
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/r3-p9en-gx67
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.