We propose observations of two ..dark. groups of galaxies to determine ifthey represent a distinct class of objects. Also known as OLEGS or ..fossilgroups., they exhibit Lx, total mass, and gas mass similar to poor clusters,but optically they contain an isolated elliptical with no significantcompanions. A striking common feature is an abnormally high total mass to lightratio (virgul500-1000 for some objects!). These results are however uncertain, and athorough investigation of these objects is needed. We have selected from theliterature 2 particularly intriguing systems which have not been well-studied.Their comparison with .normal. groups of similar mass and Lx will provide vitalinformation on the process of galaxy/group formation.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2003-07-11T21:48:26Z/2003-07-12T03:58:30Z
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, Dr Aaron Lewis, 2004, 'XMM Temperature Measurements of ''Dark.. Groups of Galaxies', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-rlrcysg
