University of Hertfordshire

By the same authors

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Original languageEnglish
Publication statusUnpublished - 5 Apr 2018


The linear bias of galaxy populations informs us about their environmental properties which can be a key driver of galaxy evolution and overall cosmological context. Radio-loud AGNs exist within the most massive galaxies and are therefore expected to be highly biased tracers of the matter field. Traditionally, measurements of bias have relied on galaxy n-point auto or cross-correlations. A promising alternative technique is that of measuring the cross-power spectrum of galaxy density fields with weak lensing maps of the cosmic microwave background (CMB) offering a very clean measurement using the CMB as a z = 1100 backlight. We measure the cross-power spectrum of 12,820 AGNs at 0.1<z<0.7, from the Best and Heckman selection of the FIRST radio galaxy catalogue, with the projected mass density from the Planck CMB lensing potential map. The amplitude of the cross-correlation signal is used to directly measure the linear bias using a spherical cut-sky approach. Here we report a 5.6휎 detection of the CMB-AGN cross-power spectrum. Using a spherical collapse formalism it is possible to estimate the halo mass from the linear bias. The results imply that radio-loud AGN typically inhabit halos of masses comparable to that of a large group of galaxies, in agreement with estimates of radio-loud AGN environments from optical and X-ray work.

ID: 16345442