English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

(abridged) MR2251-178 was the first quasar initially discovered in X-rays,and the first one found to host a warm absorber. The quasar turned out to be anoutstanding object in many respects. It has a high ratio of X-ray/opticalluminosity, is surrounded by the largest quasar emission-line nebula known, andis located in the outskirts of a cluster of galaxies. Here, we present resultsfrom an analysis of the X-ray spectral, temporal, and spatial properties ofthis source and its environment based on deep ROSAT observations.  Remarkably, we do not detect any excess X-ray cold absorption expected tooriginate from the giant gas nebula surrounding MR2251-178. This excludes thepresence of a huge HI envelope around the quasar. The X-ray spectrum ofMR2251-178 is best fit by a warm-absorbed powerlaw with an ionization parameterlog U = 0.5 and a column density log N_w = 22.6 which, however, cannot be thesame material as the giant optical emission line nebula. The mean (0.1--2.4)keVX-ray luminosity amounts to 10^{45} erg/s.  A spatial analysis shows that the bulk of the X-ray emission from the quasaris consistent with a point source, as expected in view of the powerlaw-shapedX-ray spectrum and the rapid X-ray variability we detect. In addition, extendedemission appears at weak emission levels, including a bridge between the quasarand the cD galaxy of the cluster.  The X-ray emission from the intra-cluster medium is weak or absent. None ofthe other member galaxies of the cluster to which MR 2251-178 belongs, aredetected in X-rays. However, east of the quasar there is a significant excessof X-ray sources, several of them without optical counterparts on the UKSchmidt plates.

The X-ray view of the quasar MR 2251-178 and its host cluster: Variability, absorption, and intracluster gas emission