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) We present a new sample of X-ray selected galaxy groups andclusters serendipitously observed with Swift and the X-ray Telescope (XRT). Wesearched the XRT archive for extended sources among 336 GRB fields withgalactic latitude |b|>20{\deg}. Our selection algorithm yields a flux-limitedsample of 72 X-ray groups and clusters with a well defined selection functionand negligible contamination. The sky coverage of the survey goes from thetotal 40 deg^2 to 1 deg^2 at a flux limit of 10^-14 erg/s/cm^-2 (0.5-2 keV).Here we describe the XRT data processing, the statistical calibration of thesurvey, and the catalog of detected cluster candidates. All the X-ray sourcesare detected in the Swift-XRT soft (0.5-2 keV) band. A size parameter definedas the half power radius (HPR) measured inside a box of 45x45 arcsec, isassigned to each source. We select extended sources by applying a threshold onthe Half Power Radius and we calibrate its dependence on the measured netcounts and on the image background with extensive simulations in order toidentify all the sources with ~99% probability of being extended. We computethe logN-logS of our sample, finding very good agreement with previous deepcluster surveys. A cross correlation with published X-ray catalogs shows thatonly 9 sources were already detected, none of them as extended. Therefore, ~90%of our sources are new X-ray detections. We also cross correlated our sourceswith optical catalogs, finding 20 previously identified clusters. Overall,about ~65% of our sources are new detections. The XRT follow-up observation ofGRBs is providing an excellent serendipitous survey for groups and clusters ofgalaxies, mainly thanks to the low background of XRT and its constant angularresolution across the field of view. About 33% of the sample has spectroscopicor photometric redshifts from public optical surveys.

The Swift X-ray Telescope Cluster Survey: data reduction and cluster catalog for the GRB fields