About 1/10 of the quasars can be classified as soft X-ray-weak, whose X-rayemission is by a factor 10-30 fainter than in typical quasars. They show astrong correlation between alpha OX and the C IV absorption equivalentwidth, which suggest that absorption is the primary cause of their soft X-ray-weakness. But the shape of the correlation can not be reproduced by an uniformscreen covering both the X-ray source and the ultraviolet emission. Thereforeeither the UV and X-ray absorbers are not identical (warm absorber, partly covered, only scattered flux) or the X-ray weakness is due to a peculiarproperty of the nuclear emission, as extreme variability or unusual steepness.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2002-11-03T01:06:03Z/2003-05-14T19:52:57Z
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 Norbert Schartel, 2004, 'The Nature of Soft X-Ray Weak Quasars', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-zsf5xnr
