The Atacama Cosmology Telescope: likelihood for smallscale CMB data
Abstract
The Atacama Cosmology Telescope has measured the angular power spectra of microwave fluctuations to arcminute scales at frequencies of 148 and 218 GHz, from three seasons of data. At small scales the fluctuations in the primordial Cosmic Microwave Background (CMB) become increasingly obscured by extragalactic foregounds and secondary CMB signals. We present results from a nineparameter model describing these secondary effects, including the thermal and kinematic SunyaevZel'dovich (tSZ and kSZ) power; the clustered and Poissonlike power from Cosmic Infrared Background (CIB) sources, and their frequency scaling; the tSZCIB correlation coefficient; the extragalactic radio source power; and thermal dust emission from Galactic cirrus in two different regions of the sky. In order to extract cosmological parameters, we describe a likelihood function for the ACT data, fitting this model to the multifrequency spectra in the multipole range 500 < l < 10000. We extend the likelihood to include spectra from the South Pole Telescope at frequencies of 95, 150, and 220 GHz. Accounting for different radio source levels and Galactic cirrus emission, the same model provides an excellent fit to both datasets simultaneously, with χ^{2}/dof= 675/697 for ACT, and 96/107 for SPT. We then use the multifrequency likelihood to estimate the CMB power spectrum from ACT in bandpowers, marginalizing over the secondary parameters. This provides a simplified `CMBonly' likelihood in the range 500 < l < 3500 for use in cosmological parameter estimation.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 July 2013
 DOI:
 10.1088/14757516/2013/07/025
 arXiv:
 arXiv:1301.0776
 Bibcode:
 2013JCAP...07..025D
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 18 pages, 12 figures. This paper is a companion to Das et al. (2013) and Sievers et al. (2013). Matches published JCAP version