Evolution in the bias of faint radio sources to z similar to 2.2

Journal article

Quantifying how the baryonic matter traces the underlying dark matter distribution is key to both understanding galaxy formation and our ability to constrain the cosmological model. Using the cross-correlation function of radio and near-infrared galaxies, we present a large-scale clustering analysis of radio galaxies to z ~ 2.2. We measure the angular auto-correlation function of Ks<23.5 galaxies in the VISTA Deep Extragalactic Observations (VIDEO-XMM3) field with photometric redshifts out to z = 4 using VIDEO and CFHTLS (Canada-France-Hawaii Telescope Legacy Survey) photometry in the near-infrared and optical. We then use the cross-correlation function of these sources with 766 radio sources at S1.4>90μJy to infer linear bias of radio galaxies in four redshift bins. We find that the bias evolves from b = 0.57 ± 0.06 at z ~ 0.3 to 8.55 ± 3.11 at z ~ 2.2. Furthermore, we separate the radio sources into subsamples to determine how the bias is dependent on the radio luminosity, and find a bias which is significantly higher than predicted by the simulations of Wilman et al., and consistent with the lower luminosity but more abundant FR-I population having a similar bias to the highly luminous but rare FR-IIs. Our results are suggestive of a higher mass, particularly for FR-I sources than assumed in simulations, especially towards higher redshift. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Authors: Lindsay, SN; Jarvis, M; McAlpine, K

• Publication status: Published
• Publisher: Blackwell Publishing Ltd
• Journal: Monthly Notices of the Royal Astronomical Society
• Volume: 440
• Issue: 3
• Pages: 2322-2332
• Publication date: 2014-05-01
• DOI: 10.1093/mnras/stu453
• EISSN: 1365-2966
• ISSN: 0035-8711
• Language: English
• Keywords: galaxies: active; large-scale structure of Universe; surveys; radio continuum: galaxies