The Cooling of The Neutron Star in The Cassiopeia A Supernova Remnant

  • Author / Creator
    Elshamouty, Khaled
  • A young neutron star cools mainly via neutrino emission from the star's core. Thus, the thermal evolution of neutron stars reflects changes in their core, constraining temperature-sensitive properties such as the composition of the core and the envelope of the neutron star. The neutron star in the Cassiopeia A supernova remnant (Cas A NS) is the youngest known, at only 330 years old. Heinke & Ho (2010) reported a drop of 3.6\% in its surface temperature (21\% drop in observed flux) from Chandra ACIS-S X-ray data on the Cas A NS between 2000 and 2009. This is the only young neutron star to have been observed to cool over time, permitting a clearer picture of its thermal evolution. This drop was interpreted as enhanced neutrino emission due to a superfluid transition in the core (Page et al. 2011), Shternin et al. (2011)). Here I present analysis of data from another Chandra detector (HRC-S) over the same time period to test the cooling rate. I used the best current estimates of the effective area of this detector and the spectrum of the Cas A NS to infer the countrates corresponding to various NS temperatures, and thus to compute the temperature drop from the countrate change. The temperature drop inferred from HRC-S observations is more uncertain, but is significantly less than the temperature drop inferred from ACIS-S. Observations using Chandra's other detectors suffer a variety of systematic uncertainties. The result suggests that the temperature drop could be half as large as originally suggested, but that the Cas A NS's temperature is indeed decreasing.

  • Subjects / Keywords
  • Graduation date
    Fall 2012
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • 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.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
  • Supervisor / co-supervisor and their department(s)
  • Examining committee members and their departments
    • Morsink, Sharon (Physics)
    • Sivakoff, Gregory (Physics)
    • Heinke, Craig (Physics)
    • Sanchez-Azofeifa, Arturo (Earth and Atmospheric Sciences)