We have recently discovered a population of old star clusters in the halo of M31which have colours and magnitudes typical of GCs but are much more extendedspatially. These clusters have no known analogue in the Milky Way and theirorigin remains a mystery. We seek to study their X-ray properties distinguishbetween competing scenarios for their evolution. For example, if these clustersformed as diffuse systems, their relatively low stellar densities would lead usto expect a low X-ray source population, and raise the question, do they havedark matter halos? Alternatively have they been heated to their current state bya large population of binaries and/or black holes, which would make theseclusters rich X-ray sources and viable test beds of modified gravitational theories.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2007-07-21T11:03:59Z/2008-02-09T19:47:07Z
Version
17.56_20190403_1200
Mission Description
The European Space Agencys (ESA) X-ray Multi-Mirror Mission (XMM-Newton) was launched by an Ariane 504 on December 10th 1999. XMM-Newton is ESAs second cornerstone of the Horizon 2000 Science Programme. It carries 3 high throughput X-ray telescopes with an unprecedented effective area, and an optical monitor, the first flown on a X-ray observatory. The large collecting area and ability to make long uninterrupted exposures provide highly sensitive observations. Since Earths atmosphere blocks out all X-rays, only a telescope in space can detect and study celestial X-ray sources. The XMM-Newton mission is helping scientists to solve a number of cosmic mysteries, ranging from the enigmatic black holes to the origins of the Universe itself. Observing time on XMM-Newton is being made available to the scientific community, applying for observational periods on a competitive basis.
European Space Agency, Prof Nial Tanvir, 2009, 'Probing the X-ray properties of Extend Star Clusters in the far Halo of M31', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-si3ys5k
