Reflection-dominated Seyfert 2 galaxies are usually interpreted in terms of anactive nucleus covered by a Compton-thick absorber. However, recently discoveredtransitions between reflection- and transmission-dominated (Compton-thin) statesare more convincingly explained as changes in the activity level of the ActiveGalactic Nucleus (AGN). In order to quantitatively address this issue, wepropose to complete the observations of an optically defined, complete andunbiased sample of Compton-thick Seyfert 2 galaxies, to measure on a soundstatistical basis the rate of reflection- to transmission-dominated statetransitions. This requires the observation of still 3 objects - priority Ctargets for the AO2 - for a total allocation time of 60 ks.
Instrument
EMOS1, EMOS2, EPN, OM, RGS1, RGS2
Temporal Coverage
2005-02-20T17:03:32Z/2005-02-21T00:18:48Z
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 MATTEO GUAINAZZI, 2006, 'TRANSMISSIOM- TO REFLECTION-DOMINATED SPECTRA TRANSITION IN SEYFERT 2 GALAXIES', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-ah9v5am
