Publikationsdatum:
2015-05-31
Beschreibung:
We correlate the positions of radio galaxies in the FIRST survey with the cosmic microwave background lensing convergence estimated from the Atacama Cosmology Telescope over 470 deg 2 to determine the bias of these galaxies. We remove optically cross-matched sources below redshift z = 0.2 to preferentially select active galactic nuclei (AGN). We measure the angular cross-power spectrum $C_l^{\kappa g}$ at 4.4 significance in the multipole range 100 〈 l 〈 3000, corresponding to physical scales within 2–60 Mpc at an effective redshift z eff = 1.5. Modelling the AGN population with a redshift-dependent bias, the cross-spectrum is well fitted by the Planck best-fitting cold dark matter cosmological model. Fixing the cosmology and assumed redshift distribution of sources, we fit for the overall bias model normalization, finding b ( z eff ) = 3.5 ± 0.8 for the full galaxy sample and b ( z eff ) = 4.0 ± 1.1(3.0 ± 1.1) for sources brighter (fainter) than 2.5 mJy. This measurement characterizes the typical halo mass of radio-loud AGN: we find $\log (M_{\rm halo} / \,\mathrm{M}_{\odot }) = 13.6^{+0.3}_{-0.4}$ .
Print ISSN:
0035-8711
Digitale ISSN:
1365-2966
Thema:
Physik
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