|Title||Weak Line Quasars at High Redshift: Extremely High Accretion Rate Sources?|
|Author||Prof Ohad Shemmer|
|Description||The broad C IV emission lines in weak line quasars (WLQs) are significantly weaker than expected from the anti-correlation between C IV equivalent width and the Hbeta-based Eddington ratio. This discrepancy may be reconciled if the Eddington ratios of WLQs are higher than those indicated by Hbeta. We aim to test this hypothesis by measuring the hard-X-ray photon index in all WLQs with Hbeta measurements thus obtaining robust determinations of their accretion rates. Steep spectral slopes will indicate that high accretion rates are responsible for the line weakness in WLQs. Otherwise, additional parameters may control broad emission line equivalent widths. The results will yield crucial insights about the accretion process and broad emission line formation in all active galactic nuclei.|
|Publication||Steep Hard-X-Ray Spectra Indicate Extremely High Accretion Rates in Weak Emission-line Quasars . Marlar, Andrea, Shemmer, Ohad, et all. . ApJ . 865-92 . 2018 . 2018ApJ...865...92M ,
|Instrument||EMOS1, EMOS2, EPN, OM, RGS1, RGS2|
|Mission Description||The European Space Agency's (ESA) X-ray Multi-Mirror Mission (XMM-Newton) was launched by an Ariane 504 on December 10th 1999. XMM-Newton is ESA's 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 Earth's 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.
|Publisher And Registrant||European Space Agency|
|Credit Guidelines||European Space Agency, 2018-01-24T23:00:00Z, 078236, 17.56_20190403_1200. https://doi.org/10.5270/esa-u3q2hrl|