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تسجيل مستخدم جديدDetection of the first X-ray selected large AGN group
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We have examined the spatial distribution of 856 AGN detected by the ROSAT All-Sky Survey (RASS) using a direct search for structures with the minimal spanning tree. The AGNs were compiled from an area of 7000 deg^2, in which optical identifications of RASS sources were made with the help of the digitized objective prism plates of the Hamburg Quasar Survey (HQS). Redshifts were taken from the literature or from own follow-up observations. The sample probes the spatial distribution at low redshifts, since the redshift distribution peaks at z=0.1. The application of the minimal spanning tree led to a 1.8 sigma discovery of an AGN group with 7 members in a volume V=140*75*75 h^-3Mpc^3 in the Pisces constellation. With a mean redshift z=0.27 this group is only the third discovered group at redshifts z<0.5. The RASS offers excellent possibilities to study large scale structure with AGNs at low redshifts, once these redshifts are determined.
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We are searching for large-scale structures in the distribution of AGN discovered by the ROSAT All-Sky Survey. The RASS detected > 60000 X-ray objects, of which approximately 35% are AGN at z < 0.5. The surface density in the extragalactic sky is app
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