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تسجيل مستخدم جديدCharacterisation of AGN from the XMM-Newton Slew Survey
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R. L. C. Starling
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We present optical spectroscopy of candidate AGN pinpointed by a Swift follow-up campaign on unidentified transients in the XMM-Newton Slew Survey, increasing the completeness of the identifications of AGN in the Survey. Our Swift follow-up campaign identified 17 XRT-detected candidate AGN, of which nine were selected for optical follow-up and a further two were confirmed as AGN elsewhere. Using data obtained at the William Herschel Telescope, Very Large Telescope and New Technology Telescope, we find AGN features in seven of the candidates. We classify six as Seyfert types 1.0 to 1.5, with broad-line region velocities spanning 2000--12000 km s$^{-1}$, and identify one as a possible Type II AGN, consistent with the lack of a soft band X-ray detection in the Slew Survey. The Virial black hole mass estimates for the sample lie between 1$times$10$^{8}$ M$_{odot}$ and 3$times$10$^9$ M$_{odot}$, with one source likely emitting close to its Eddington rate, $L_{rm Bol}/L_{rm Edd} sim 0.9$. We find a wide redshift range of $0.08<z<0.9$ for the nine now confirmed AGN drawn from the unidentified Slew Survey sample. One source remaining unclassified shows outbursts rarely seen before in AGN. We conclude that AGN discovered in this way are consistent with the largely non-varying, Slew-selected, known AGN population. We also find parallels with XMM-Newton Bright Serendipitous Survey AGN selected from pointed observations, and postulate that shallow X-ray surveys select AGN drawn from the same populations that have been characterised in deeper X-ray selected samples.
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XMM-Newton, with the huge collecting area of its mirrors and the high quantum efficiency of its EPIC detectors, is the most sensitive X-ray observatory ever flown. This is strikingly evident during slew exposures, which, while yielding only at most 1
4 seconds of on-source exposure time, actually constitute a 2-10 keV survey ten times deeper than all other all-sky surveys. The current (April 2005) XMM archive contains 374 slew exposures which give a uniform coverage over around 10,000 square degrees (approx. 25% of the sky). Here we describe the results of pilot studies, the current status of the XMM-Newton Slew Survey, up-to-date results and our progress towards constructing a catalogue of slew detections in the full 0.2-12 keV energy band.
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