The Atacama Cosmology Telescope: measuring radio galaxy bias through cross-correlation with lensing
astro-ph.CO
/ Authors
Rupert Allison, Sam N. Lindsay, Blake D. Sherwin, Francesco de Bernardis, J. Richard Bond, Erminia Calabrese, Mark J. Devlin, Joanna Dunkley, Patricio Gallardo, Shawn Henderson
and 18 more authors
Adam D. Hincks, Renee Hlozek, Matt Jarvis, Arthur Kosowsky, Thibaut Louis, Mathew Madhavacheril, Jeff McMahon, Kavilan Moodley, Sigurd Naess, Laura Newburgh, Michael D. Niemack, Lyman A. Page, Bruce Partridge, Neelima Sehgal, David N. Spergel, Suzanne T. Staggs, Alexander van Engelen, Edward J. Wollack
/ Abstract
We correlate the positions of radio galaxies in the FIRST survey with the CMB lensing convergence estimated from the Atacama Cosmology Telescope over 470 square degrees 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 $C_l^{κg}$ at $4.4σ$ significance in the multipole range $100<l<3000$, corresponding to physical scales between $\approx$ 2--60 Mpc at an effective redshift $z_{\rm eff}= 1.5$. Modelling the AGN population with a redshift-dependent bias, the cross-spectrum is well fit by the Planck best-fit $Λ$CDM cosmological model. Fixing the cosmology we fit for the overall bias model normalization, finding $b(z_{\rm eff}) = 3.5 \pm 0.8$ for the full galaxy sample, and $b(z_{\rm eff})=4.0\pm1.1 (3.0\pm1.1)$ for sources brighter (fainter) than 2.5 mJy. This measurement characterizes the typical halo mass of radio-loud AGN: we find $\log(M_{\rm halo} / M_\odot) = 13.6^{+0.3}_{-0.4}$.