The baryon fraction (f_b) in collapsed massive halos has great cosmologicalsignificance, and comprises hot gas and stars --- both in galaxies and theintracluster light (ICL). While the gas mass is known to be depleted in groups,it is not clear if the missing baryons have been ejected from the halo or aresimply locked up in stars. The best current study suggests an increasing ICLfraction in groups offsets a declining gas fraction, implying a universal f_b,but this is based on only 2 low mass groups, with only estimated stellar baryonmasses. We propose to observe the only 4 poor groups for which astate-of-the-art measurement of intragroup stellar baryons has been made, to mapthe hot gas and thereby discriminate definitively between these two scenarios.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2008-08-02T03:38:55Z/2010-10-29T21:54:35Z
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 Alastair Sanderson, 2011, 'The baryon fraction in group-sized halos', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-uuxjco2
