The discovery of a massive supercluster at z = 0.9 in the UKIDSS deep eXtragalactic survey
Monthly Notices of the Royal Astronomical Society 379:4 (2007) 1343-1351
Abstract:
We analyse the first publicly released deep field of the UK Infrared Deep Sky Survey (UKIDSS) Deep eXtragalactic Survey to identify candidate galaxy overdensities at z ∼ 1 across ∼1 deg2 in the ELAIS-N1 field. Using I - K, J - K and K - 3.6 μm colours, we identify and spectroscopically follow up five candidate structures with Gemini/Gemini Multi-Object Spectrograph and confirm that they are all true overdensities with between five and 19 members each. Surprisingly, all five structures lie in a narrow redshift range at z = 0.89 ± 0.01, although they are spread across 30 Mpc on the sky. We also find a more distant overdensity at z = 1.09 in one of the spectroscopic survey regions. These five overdense regions lying in a narrow redshift range indicate the presence of a supercluster in this field and by comparing with mock cluster catalogues from N-body simulations we discuss the likely properties of this structure. Overall, we show that the properties of this supercluster are similar to the well-studied Shapley and Hercules superclusters at lower redshift. © 2007 RAS.Spectroscopic follow-up of a cluster candidate at z=1.45
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 382:3 (2007) 971-984
Deep spectroscopy of a young radio source at z = 0.521
Astronomische Nachrichten Wiley 327:2‐3 (2006) 171-174
15-GHz variability of 9C sources
Monthly Notices of the Royal Astronomical Society 370:3 (2006) 1556-1564
Abstract:
We present results from a 3-yr study of the 15-GHz variability of 51 9C sources. 48 of these sources make up a subsample of a larger one complete to 25 mJy in 9C, and as the sources are selected pseudo-randomly the results should be representative of the complete sample. 29 per cent of this subsample are found to be variable above the flux calibration uncertainties of ∼6 per cent. 50 per cent of the flat-spectrum objects are variable whilst none of the steep-spectrum objects or the objects with convex spectra peaking below 5 GHz are variable. Nine of the objects studied have convex spectra and peak frequencies above 5 GHz; eight of these were found to vary at 15 GHz, suggesting that the high-frequency peaking class in this sample is largely populated by objects with jets aligned close to the line of sight whose emission is dominated by beamed components. © 2006 RAS.5-GHz MERLIN and VLBA observations of compact 9C sources
Monthly Notices of the Royal Astronomical Society 367:1 (2006) 323-330