GT-The X-ray-to-optical energy distribution of quasars, alpha_ox, is requiredto relate the quasar statistics, evolution and luminosity function in the twowavebands and to understand its. broad band emission. In a recent study ofradio-quiet quasars from ROSAT observations there is a small number of objectsshowing very weak X-ray emission compared to their optical luminosity. Thenature of these X-ray quiet quasars is unknown and it is not clear whether theyare the X-ray quiet extremes of a continous distribution or a distinct class ofobjects. XMM observations seem to be the only way to understand this newpopulation of quasars and to distinguish different explanations for the unknownphysical nature of these objects.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2000-11-04T23:35:48Z/2002-07-10T15:55:52Z
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 Bernd Aschenbach, 2003, 'Are there X-ray quiet quasars', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-7ab43zm
