Gravitational lensing of the CMB by galaxy clusters

¹ Dipartimento di Astronomia, Università di Padova, vicolo dell'Osservatorio 2, 35122 Padova, Italy e-mail: maturi@pd.astro.it
² Institut für Theoretische Astrophysik, Universität Heidelberg, Albert-Ueberle Strasse 2, 69121 Heidelberg, Germany
³ Max-Planck-Institut für Astrophysik, PO Box 1317, 85740 Garching, Germany
⁴ Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy

Received: 3 August 2004
Accepted: 24 February 2005

Abstract

We adapt a non-linear filter proposed by Hu (2001) for detecting lensing of the CMB by large-scale structures to recover surface-density profiles of galaxy clusters from their localised, weak gravitational lensing effect on CMB fields. Shifting the band-pass of the filter to smaller scales, and normalising it such as to reproduce the convergence rather than the deflection angle, we find that the mean density profile of a sample of 100 clusters can be recovered to better than 10% from well within the scale radius to almost the virial radius. The kinetic Sunyaev-Zel'dovich effect is shown to be a negligible source of error. We test the filter applying it to data simulated using the characteristics of the Atacama Cosmology Telescope (ACT), showing that it will be possible to recover mean cluster profiles outside a radius of  corresponding to ACT's angular resolution.