Amir Hajian

Detection of the power spectrum of cosmic microwave background lensing by the Atacama Cosmology Telescope.

We report the first detection of the gravitational lensing of the cosmic microwave background through a measurement of the four-point correlation function in the temperature maps made by the Atacama Cosmology Telescope. We verify our detection by calculating the levels of potential contaminants and performing a number of null tests. The resulting convergence power spectrum at 2° angular scales measures the amplitude of matter density fluctuations on comoving length scales of around 100 Mpc at redshifts around 0.5 to 3. The measured amplitude of the signal agrees with Lambda cold dark matter cosmology predictions. Since the amplitude of the convergence power spectrum scales as the square of the amplitude of the density fluctuations, the 4σ detection of the lensing signal measures the amplitude of density fluctuations to 12%.

The Atacama Cosmology Telescope: a measurement of the cosmic microwave background power spectrum at 148 and 218 GHz from the 2008 southern survey

We present measurements of the cosmic microwave background (CMB) power spectrum made by the Atacama Cosmology Telescope at 148 GHz and 218 GHz, as well as the cross-frequency spectrum between the two channels. Our results clearly show the second through the seventh acoustic peaks in the CMB power spectrum. The measurements of these higher-order peaks provide an additional test of the ΛCDM cosmological model. At l>3000, we detect power in excess of the primary anisotropy spectrum of the CMB. At lower multipoles 500 < l < 3000, we find evidence for gravitational lensing of the CMB in the power spectrum at the 2.8σ level. We also detect a low level of Galactic dust in our maps, which demonstrates that we can recover known faint, diffuse signals.

Measuring the Statistical Isotropy of the Cosmic Microwave Background Anisotropy

The statistical expectation values of the temperature fluctuations of the cosmic microwave background (CMB) are assumed to be preserved under the rotations of the sky. This assumption of the statistical isotropy (SI) of the CMB anisotropy should be observationally verified since detection of a violation of SI could have profound implications for cosmology. We propose a set of measures, κl (l = 1, 2, 3, ...), for detecting a violation of SI in an observed CMB anisotropy sky map indicated by nonzero κl. We define an estimator for the κl spectrum and analytically compute its cosmic bias and cosmic variance. The results match those obtained by measuring κl using simulated sky maps. Nonzero (bias-corrected) κl larger than the SI cosmic variance will imply a violation of SI. The SI measure proposed in this Letter is an appropriate statistic to investigate a preliminary indication of SI violation in the recently released Wilkinson Microwave Anisotropy Probe data.The statistical expectation values of the temperature fluctuations of cosmic microwave background (CMB) are assumed to be preserved under rotations of the sky. This assumption of {\em statistical isotropy} (SI) of the CMB anisotropy should be observationally verified since detection of violation of SI could have profound implications for cosmology. We propose a set of measures,

Evidence for dark energy from the cosmic microwave background alone using the Atacama Cosmology Telescope lensing measurements.

\kappa_\ell

Next Generation Redshift Surveys and the Origin of Cosmic Acceleration

(

Cosmological parameters from pre-planck cosmic microwave background measurements

\ell=1,2,3, ...

The Atacama Cosmology Telescope: Extragalactic Sources at 148 GHz in the 2008 Survey

) for detecting violation of statistical isotropy in an observed CMB anisotropy sky map indicated by non zero

THE HERSCHEL STRIPE 82 SURVEY (HERS): MAPS AND EARLY CATALOG †

\kappa_\ell

The Atacama Cosmology Telescope: Cross-Correlation of Cosmic Microwave Background Lensing and Quasars

. We define an estimator for the

Inhomogeneities in the microwave background radiation interpreted within the framework of the quasi-steady state cosmology

\kappa_\ell