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X-Ray Emission from the Halo of M31Our goal was to use short (10 ksec) observations of selected fields in the halo of M31, to determine the size and characteristics of its X-ray population and to study the connection between globular clusters and X-ray sources. The program of observations has yet to be successfully completed. We received acceptable data from just 2 of the 5 approved fields. Nevertheless, the results were intriguing and we have submitted a paper based on this data to Nature. We find that the X-ray source density is significantly enhanced in the vicinity of one GC, providing the first observational evidence supporting the ejection hypothesis. We also find additional X-ray sources, including some which are very soft, in large enough numbers to suggest that not all could have been formed in GCs. That is, some must be descended from the same primordial halo population that produced any compact stars comprising part of the halo's dark matter. Extrapolating fiom the X-ray source population, we estimate that stellar remnants and dim old stars in the halo could comprise as much as 25% of the estimated mass (approx. 10(exp 12) Solar Mass) of the halo. These results suggest that the other approved fields should be observed soon and also provide strong motivation for the future XMM-Newton programs.
Document ID
20040058057
Acquisition Source
Headquarters
Document Type
Contractor or Grantee Report
Authors
Mushotzky, Richard
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
DiStefano, Rosanne
(Smithsonian Astrophysical Observatory Cambridge, MA, United States)
Date Acquired
August 21, 2013
Publication Date
April 1, 2004
Subject Category
Astrophysics
Funding Number(s)
CONTRACT_GRANT: NAG5-13090
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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