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

We report the serendipitous detection of a significant overdensity ofHerschel-SPIRE 250 micron sources in the vicinity of MRC1138-26. We use anadaptive kernel density estimate to quantify the significance, including acomparison with other fields. The overdensity has a size of ~3.5-4' and standsout at ~5sigma with respect to the background estimate. No features withsimilar significance were found in four extragalactic control fields:GOODS-North, Lockman, COSMOS and UDS. The chance of having a similaroverdensity in a field with the same number but randomly distributed sources isless than 2%. The clump is also visible as a low surface brightness feature inthe Planck 857 GHz map. We detect 76 sources at 250 micron (with asignal-to-noise ratio greater than 3), in a region of 4' radius; 43 of thoseare above a flux density limit of 20 mJy. This is a factor of 3.6 in excessover the average in the four control fields, considering only the sources above20 mJy. We also find an excess in the number counts of sources with 250 micronflux densities between 30 and 40 mJy, compared to deep extragalacticblank-field number counts. Assuming a fixed dust temperature (30 K) andemissivity (beta=1.5) a crude, blackbody-derived redshift distribution, zBB, ofthe detected sources is significantly different from the distributions in thecontrol fields and exhibits a significant peak at zBB ~ 1.5, although theactual peak redshift is highly degenerate with the temperature. We tentativelysuggest, based on zBB and the similar S250/S350 colours of the sources withinthe peak, that a significant fraction of the sources in the clump may be at asimilar redshift. Since the overdensity lies ~7' south of the z=2.16 Spiderwebprotocluster MRC1138-26, an intriguing possibility (that is presentlyunverifiable given the data in hand) is that it lies within the samelarge-scale structure.(abridged)

Serendipitous detection of an overdensity of Herschel-SPIRE 250 micron sources south of MRC1138-26