47 research outputs found
First measurement of the cross-correlation of CMB lensing and galaxy lensing
We measure the cross-correlation of cosmic microwave background (CMB) lensing convergence maps derived from Atacama Cosmology Telescope data with galaxy lensing convergence maps as measured by the Canada-France-Hawaii Telescope Stripe 82 Survey. The CMB-galaxy lensing cross power spectrum is measured for the first time with a significance of 4.2σ, which corresponds to a 12% constraint on the amplitude of density fluctuations at redshifts ∼0.9. With upcoming improved lensing data, this novel type of measurement will become a powerful cosmological probe, providing a precise measurement of the mass distribution at intermediate redshifts and serving as a calibrator for systematic biases in weak lensing measurements
Weak-lensing mass calibration of the Atacama Cosmology Telescope equatorial Sunyaev-Zeldovich cluster sample with the Canada-France-Hawaii telescope stripe 82 survey
Mass calibration uncertainty is the largest systematic effect for using clusters of galaxies to constrain cosmological parameters. We present weak lensing mass measurements from the Canada-France-Hawaii Telescope Stripe 82 Survey for galaxy clusters selected through their high signal-to-noise thermal Sunyaev-Zeldovich (tSZ) signal measured with the Atacama Cosmology Telescope (ACT). For a sample of 9 ACT clusters with a tSZ signal-to-noise greater than five the average weak lensing mass is (4.8±0.8) ×1014 Mo, consistent with the tSZ mass estimate of (4.70±1.0) ×1014 Mo which assumes a universal pressure profile for the cluster gas. Our results are consistent with previous weak-lensing measurements of tSZ-detected clusters from the Planck satellite. When comparing our results, we estimate the Eddington bias correction for the sample intersection of Planck and weak-lensing clusters which was previously excluded
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Two-season Atacama Cosmology Telescope polarimeter lensing power spectrum
© 2017 American Physical Society. We report a measurement of the power spectrum of cosmic microwave background (CMB) lensing from two seasons of Atacama Cosmology Telescope polarimeter (ACTPol) CMB data. The CMB lensing power spectrum is extracted from both temperature and polarization data using quadratic estimators. We obtain results that are consistent with the expectation from the best-fit Planck ΛCDM model over a range of multipoles L=80-2100, with an amplitude of lensing Alens=1.06±0.15(stat)±0.06(sys) relative to Planck. Our measurement of the CMB lensing power spectrum gives σ8Ωm0.25=0.643±0.054; including baryon acoustic oscillation scale data, we constrain the amplitude of density fluctuations to be σ8=0.831±0.053. We also update constraints on the neutrino mass sum. We verify our lensing measurement with a number of null tests and systematic checks, finding no evidence of significant systematic errors. This measurement relies on a small fraction of the ACTPol data already taken; more precise lensing results can therefore be expected from the full ACTPol data set.This
work was supported by the U.S. National Science Foundation
(NSF) through Grants. No. AST-1440226, No. AST-0965625
and No. AST-0408698 for the ACT project, as well as Grants
No. PHY-1214379 and No. PHY-0855887. Funding was also
provided by Princeton University, the University of
Pennsylvania, and a Canada Foundation for Innovation
(CFI) grant to U. B. C. A. C. T. operates in the Parque
Astronómico Atacama in northern Chile under the auspices
of the Comisión Nacional de Investigación Científica y
Tecnológica de Chile (CONICYT). Computations were
performed on the GPC supercomputer at the SciNet HPC
Consortium. SciNetis funded bytheCFI under the auspices of
Compute Canada, the Government of Ontario, the Ontario
Research Fund Research Excellence, and the University of
Toronto. The development of multichroic detectors and lenses
was supported by NASA Grants No. NNX13AE56G and
No. NNX14AB58G. N. S. acknowledges support from NSF
Grant No. 1513618. A. K. has been supported by NSF Grant
No. AST-1312380. R. D. and L. M. thank CONICYT for
Grants No. ALMA-CONICYT 31140004, No. FONDECYT 1141113, No. Anillo ACT-1417 and BASAL CATA. We also
thank the Mishrahi Fund and the Wilkinson Fund for their
generous support of the project
Atrioventricular and interventricular delay optimization in cardiac resynchronization therapy: physiological principles and overview of available methods
In this review, the physiological rationale for atrioventricular and interventricular delay optimization of cardiac resynchronization therapy is discussed including the influence of exercise and long-term cardiac resynchronization therapy. The broad spectrum of both invasive and non-invasive optimization methods is reviewed with critical appraisal of the literature. Although the spectrum of both invasive and non-invasive optimization methods is broad, no single method can be recommend for standard practice as large-scale studies using hard endpoints are lacking. Current efforts mainly investigate optimization during resting conditions; however, there is a need to develop automated algorithms to implement dynamic optimization in order to adapt to physiological alterations during exercise and after anatomical remodeling
Cosmological parameters from pre-Planck CMB measurements: A 2017 update
We present cosmological constraints from the combination of the full mission nine-year WMAP release and small-scale temperature data from the pre-Planck Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT) generation of instruments. This is an update of the analysis presented in Calabrese et al. [Phys. Rev. D 87, 103012 (2013)], and highlights the impact on ΛCDM cosmology of a 0.06 eV massive neutrino—which was assumed in the Planck analysis but not in the ACT/SPT analyses—and a Planck-cleaned measurement of the optical depth to reionization. We show that cosmological constraints are now strong enough that small differences in assumptions about reionization and neutrino mass give systematic differences which are clearly detectable in the data.We recommend that these updated results be used when comparing cosmological constraints from WMAP, ACT and SPT with other surveys or with current and future full-mission Planck cosmology. Cosmological parameter chains are publicly available on the NASA’s LAMBDA data archive
The Atacama Cosmology Telescope: measuring radio galaxy bias through cross-correlation with lensing
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. 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 < sup > 2 < /sup > 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 < inf > l < /inf > < sup > kg < /sup > at 4.4σ significance in the multipole range 100 < l < 3000, corresponding to physical scales within ≈2-60 Mpc at an effective redshift z < inf > eff < /inf > = 1.5. Modelling the AGN population with a redshift-dependent bias, the cross-spectrum is well fitted by the Planck best-fitting Λ 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 < inf > eff < /inf > ) = 3.5 ± 0.8 for the full galaxy sample and b(z < inf > eff < /inf > ) = 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 < inf > halo < /inf > /M < inf > ⊙ < /inf > ) = 13.6 < inf > -0.4 < /inf > < sup > +0.3 < /sup >
The Atacama Cosmology Telescope: measuring radio galaxy bias through cross-correlation with lensing
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. 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 kg at 4.4σ significance in the multipole range 100 eff = 1.5. Modelling the AGN population with a redshift-dependent bias, the cross-spectrum is well fitted by the Planck best-fitting Λ 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 halo /M ⊙ ) = 13.6 -0.4 +0.3
