Multi-Wavelength Identification of Galactic X-ray Sources

• Author / Creator

  Gazer, Reuben S.

• We explore the production and observation of high energy (X-ray and ultraviolet/UV) radiation in the context of Galactic, compact binary systems. At the end of the stellar lifecycle, a star collapses into one of three compact objects (COs) depending on the mass at the time of collapse: a white dwarf (WD), neutron star (NS) or a black hole (BH). These dense, stellar remnants are often found in close orbits (a ∼ R⊙) with another star whose atmosphere can flow to the CO, releasing massive amounts of gravitational energy in the process. These systems are known as X-ray binaries (XRBs) for the complex interaction of the stellar pair and constituent matter manifests in bright X-ray luminosities of L_X ∼ 10^32 − 10^42 erg/s making them among the brightest X-ray emitters in the sky. The formation and distribution of XRBs is still not fully understood, in part because a homogeneous sample of Galactic XRBs is not yet available due to selection effects biased towards bright and transient sources. The Galactic Bulge Survey (GBS) was designed to identify a large, quiescent population and found 1640 unique X-ray sources in 12 square degrees near the Galactic Plane. Most systems are still unclassified, specifically those in dense optical or infrared (IR) fields where the true source of X-ray emission can be visually ambiguous. We avoid this ambiguity for 269 of 1640 systems by using UV data from GALEX to identify the correct optical/IR counterparts, making use of the low GALEX surface density (and high correlation with X-ray sources). We then create and model spectral energy distributions for each system. We identify a new group of 15 − 25 likely compact binary systems by their excess UV fluxes and classify ∼ 150 GBS systems as nearby, chromospherically-active stars. Finally, we discuss our results in the context of the GBS and suggest future research directions.

• Subjects / Keywords

  • Binary
  • Xray
  • Astrophysics

• Graduation date

  Spring 2018

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R38W38H6C

• 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.